Quarterly Mangrove. Report Dredging Report 5. Quarterly Mangrove Community. Report 5. Ichthys Nearshore Environmental Monitoring Program

Transcription

1 Quarterly Mangrove Quarterly Mangrove Community Community Health Monitoring Health Report Monitoring Dredging Report Dredging Report 5 Report 5 Ichthys Nearshore Environmental Monitoring Program L384-AW-REP Prepared for INPEX January 2014

2 Document Information Prepared for INPEX Project Name File Reference L384-AW-REP-10034_0_Quarterly Mangrove Community Health Report 5.docm Report Reference L384-AW-REP Date January 2014 Contact Information Cardno (NSW/ACT) Pty Ltd Cardno (WA) Pty Ltd Cardno (NT) Pty Ltd Level 9, The Forum 11 Harvest Terrace Level 6, 93 Mitchell Street 203 Pacific Highway West Perth WA 6005 Darwin NT 0800 St Leonards NSW 2065 Telephone: Telephone: Telephone: Facsimile: Facsimile: Facsimile: International: International: International: Document Control Version Date Author Author Initials Reviewer Reviewer Initials A 03/01/2014 Jo Buckee JB Russell Hanley RH Kristin Metcalfe KM Christopher Holloway CGH B 10/01/2014 Joanna Browne JGB Russell Hanley RH Jo Buckee JB Arianwen Morris AM Joanna Lamb JL 0 15/01/2014 Joanna Browne JGB Joanna Lamb JL This document is produced by Cardno solely for the benefit and use by the client in accordance with the terms of the engagement for the performance of the Services. Cardno does not and shall not assume any responsibility or liability whatsoever to any third party arising out of any use or reliance by any third party on the content of this document. Prepared for INPEX Cardno Page ii

3 Executive Summary A Mangrove Community Health (MCH) Monitoring Program has been developed to detect potential changes in mangrove flora and to infer whether any changes are a result of intertidal sedimentation occurring from dredging and/or spoil disposal activities associated with the Ichthys Project (the Project) in Darwin Harbour. The program focuses on the potential impacts from increased sedimentation on the health of the four main mangrove assemblages at areas in Darwin Harbour that are predicted to receive maximum levels of sedimentation associated with dredging operations. MCH is monitored at six Impact sites and compared against natural conditions at four Control sites and refers to the benchmark provided by Baseline Phase information collected at these sites prior to the commencement of dredging. These datasets are collected in parallel with the Intertidal Sedimentation and Remote Sensing Monitoring Programs to provide a suite of early warning indicators for assessing the health of mangroves in Darwin Harbour. Intertidal sedimentation is monitored at mangrove sites due to its potential to reduce the health of plants, while remote sensing is undertaken primarily to monitor changes in the health of mangroves at a harbour-wide scale. This report presents the findings of the fifth routine quarterly monitoring survey during dredging (D5: 17 October 2013 to 11 November 2013) for the MCH Monitoring Program. Dredging for Season One of the East Arm dredging component of the Project was completed on 30 April 2013, and recommenced on 1 November The Gas Export Pipeline (GEP) dredging compnent of the Project commenced on 23 October Therefore minimal dredging (maximum of 19 days) took place during the three-month period prior to D5 data collection. As of 30 April 2013, the overall dredging progress of East Arm was approximately 43% of the proposed total to be removed during the dredging program. The survey was undertaken in accordance with the methodology outlined in the Nearshore Environmental Monitoring Plan (NEMP) (Cardno 2013a). This report compares data collected during Baseline Phase survey 2 (B2: July/August 2012) with results from D5 and presents the results of statistical analyses undertaken to detect potential impacts on MCH associated with dredging. For the reactive flora indicator of canopy cover, the net change between Control and Impact sites from B2 to D5 (a decline of 1.0%) was well below the Level 2 trigger level (>30% net change). Although the relative decrease in canopy cover between Dredging and Baseline Phases was significant at Impact sites, the change was small (-1.0%) relative to overall canopy cover at Impact sites (86.2%), there was no increase in the magnitude of change and results were consistent with previous surveys. As discussed in previous reports, the changes were most likely due to the patchy canopy cover in the Seaward assemblage at all sites (Cardno and EcoScience NT 2012, 2013a, 2013b, 2013c and 2013d). Net sedimentation based on stake measurements in the Seaward assemblage for D5 (October/November 2013) continued to increase relative to the Baseline Phase, with 16.4 mm ± 1.4 SE recorded for pooled Impact sites (Cardno 2013b). However, given that apparent changes in sedimentation levels were less than 50 mm (level in which sedimentation may potentially start to impact mangrove health) and changes in canopy were similar to previous reports, the overall decline in canopy cover is considered unrelated to dredging via the intertidal sedimentation impact pathway. Other reactive flora indicators measured during D5 (October/November 2013) (i.e. seedling growth and survival) showed no evidence of impacts from dredging as sedimentation at all monitoring sites has remained well below levels (50 mm) that may potentially impact mangrove health. Net seedling survival (pooled Impact pooled Control sites) showed a decline of 8.0%, but did not exceed the Level 2 trigger levels (>50% net change in seedling growth and survival). Net change from B2 (pooled Impact pooled Control sites) in seedling growth was 1.0% based on leaf counts and -3.8% based on node counts. Patterns in seedling senescence were similar to the previous survey (D4, July 2013) with senescence of seedlings recorded in all assemblages at all sites. For individual sites there was large variability in seedling numbers, and survival rates, with high attrition rates in some assemblages. In the Hinterland Margin at Site I2 there was 0.0% survival since B2 and in the Tidal Flat assemblage at Site C2 only 5% of seedlings survived since B2. This is likely to be due to naturally occurring recruitment processes and it is well documented that mangrove seedling mortality is naturally high during the first year after establishment (Smith 1987). In a pattern similar to previous surveys, the surviving seedlings continued to exhibit growth since B2. Prepared for INPEX Cardno Page iii

4 When D5 (October/November 2013) net sedimentation within assemblages was compared with the key flora indicators of change in canopy cover, seedling survival, leaf and node change, the only (weakly) significant relationship detected between intertidal sedimentation and any of the key flora indicators showed increased growth associated with higher levels of sedimentation. Two hundred and forty seven mangrove fauna species were identified during D5 from 8,402 individuals. During the D5 survey, nine of the species documented represent new taxonomic records for Darwin Harbour mangrove communities. The total of 247 species recorded during D5 was highly consistent with previous surveys (249 species for both D2 (January/February 2013) and D3 (April/May 2013)). To date, fauna surveys for the MCH Monitoring Program have produced 68 new taxonomic records from mangroves in Darwin Harbour comprising 18 worms, 17 molluscs, 16 crustaceans, 11 ants, four fish and two other fauna species. Overall, 393 different species have been recorded from 41,606 records during the six faunal surveys conducted from June 2012 to November 2013 (B1, B2, D1, D2, D3 and D5). Mean richness and abundance of fauna during D5 was similar to the D3 survey; however, there were some differences between the Baseline and Dredging Phases in the relative change in species richness, abundance and composition at some locations in some assemblages. Patterns in faunal richness and abundance recorded during D5 were similar to those found in D1, which was conducted during the same season. This suggests that the slight declines in faunal diversity since D2 and D3 in the two most landward assemblages (the Hinterland Margin and Tidal Flat) were associated with late dry season increases in salinity and aridity combined with diminished frequency and amplitude of tidal inundation. As documented in all previous reports, species composition, richness and abundance of fauna differed significantly between the four main mangrove assemblages and faunal species richness increased steadily from landward to seaward. Species abundance was consistently highest in the Seaward assemblage and was also high in the Tidal Flat, typically exceeding that recorded for the Tidal Creek, which is lower in the intertidal zone. Less frequent tidal inundation of the extensive Ceriops forests of the Tidal Flat may to some extent protect the fauna from predators that forage in mangroves at high tide, contributing to the observed high abundance. Monitoring indicated that increases in species abundance were consistently greater at Impact sites than in Control sites, a pattern evident during all surveys throughout the Dredging Phase. In summary, fauna sampling during D5 revealed an overall slight increase in faunal diversity and abundance; however, there were differences between the Baseline and Dredging Phases in the relative change in species richness, abundance and composition at some locations in some assemblages. The majority of these changes are likely to be associated with the seasonal changes (i.e. dry to wet season) during the period since the Baseline Phase. Prepared for INPEX Cardno Page iv

5 Glossary Term or Acronym ANOVA Assemblage/Zone Definition Analysis of Variance Major mangrove community assemblages in Darwin Harbour: the Hinterland Margin, Salt Flat, Tidal Flat (Ceriops zone), Tidal Creek (Rhizophora zone) and Seaward (Sonneratia zone) B1, B2 (July/August 2012) Baseline surveys 1 (2 to 27 June 2012) and 2 (18 July 2012 to 11 August 2012) undertaken prior to the commencement of dredging activities Bray-Curtis dissimilarity index Canopy Cover Control CSIRO Densiometer DoE DSDMP DSEWPaC EA An index of dissimilarity between samples in the types and relative abundance of species The proportion of the forest floor covered by the tree crowns Sites that are considered to be unaffected by dredging Commonwealth Scientific and Industrial Research Organisation Instrument for measurement of canopy cover Department of the Environment Dredging and Spoil Disposal Management Plan Department of Sustainability, Environment, Water, Population and Communities East Arm D1 Quarterly Dredging survey 1: 27 October 2012 to 22 November 2012 D2 Quarterly Dredging survey 2: 24 January 2013 to 17 February 2013 D3 D4 Quarterly Dredging survey 3: 23 April 2013 to 17 May 2013 Quarterly Dredging survey 4: 22 July 2013 to 31 July 2013 D5 Quarterly Dredging Survey 5: 17 October 2013 to 10 November 2013 GEP Gas Export Pipeline Prepared for INPEX Cardno Page v

6 Term or Acronym ISMCHMP Location/Site Leaf-litter MAGNT Mangrove monitoring plot MBACI MCH NEMP Node NT EPA PERMANOVA Phase Sapling Seedling Station Survey Transects TSHD Definition Intertidal Sedimentation and Mangrove Community Health Monitoring Program Places where repeated sampling and measurements occurred. For this scope, locations and sites are one and the same Dead plant material, such as leaves, bark and twigs that has been shed from plants Museum and Art Gallery of the Northern Territory Permanent 20 m x 20 m area within which flora are monitored Analytical framework which incorporates Multiple sampling times Before and After at multiple Control and Impact locations or sites Mangrove Community Health Nearshore Environmental Monitoring Plan (Cardno 2013a) The point on a stem where a leaf is attached or has been attached (also called leaf internode) Northern Territory Environment Protection Authority Permutational Multivariate Analysis of Variance Sampling period in relation to dredging program (includes Baseline, Dredging and Post-dredging Phases) A young plant >1.0 m in height and with a stem girth 20 mm A young plant <1.0 m in height A place within the monitoring sites where sampling is done Sampling period e.g. Baseline 1 (B1) Access route and line of monitoring plots and stations from the hinterland to seaward margin Trailing Suction Hopper Dredgers Prepared for INPEX Cardno Page vi

7 Table of Contents Executive Summary iii Glossary 1 Introduction Background Requirement to Monitor Mangrove Health Results of Baseline Phase Surveys Objectives 2 2 Methodology Survey Timing Sampling Design Sites Assemblages, Plots and Transects Field Methodology Canopy Cover Seedling and Sapling Density, Recruitment and Species Richness Seedling Survival and Growth Photo-monitoring Fauna Statistical Analyses and Trigger Tests Flora Indicators Fauna Indicators Statistical Design and Analysis of Variance Faunal community composition analysis Assessment against Trigger Values Relationships between Flora Indicators and Intertidal Sedimentation Quality Control Collection of Field Data Data Management and Analyses 12 3 Dredging Operations 13 4 Results Flora Results Canopy Cover Seedling and Sapling Density and Recruitment Seedling Survival and Growth Photo-monitoring Fauna Results General Findings New Taxonomic Records Species Richness Abundance Fauna Community Composition 42 5 Discussion Mangrove Community Health Flora Mangrove Community Health Fauna 47 6 Conclusions 49 v Prepared for INPEX Cardno Page vii

8 7 Acknowledgements 50 8 References 51 Tables Table 1-1 Overview of ISMCHMP monitoring methods and indicators 3 Table 2-1 Summary of ISMCHMP survey dates 4 Table 2-2 Field sampling dates for MCH monitoring during D5 5 Table 2-3 MCH Monitoring Sites 5 Table 3-1 East Arm dredge footprint summary 13 Table 4-1 Table 4-2 Table 4-3 Table 4-4 Mean percentage canopy cover (± SE) recorded during B2 (July/August 2012) and D5 (October/November 2013) for Control and Impact sites for the four mangrove assemblages 16 Summary of mean canopy cover (± SE) recorded for each assemblage at Control and Impact sites during B2 (July/August 2012) and D5 (October/November 2013) 18 Mean (± SE) canopy cover change between B2 (July/August 2012) and D5 (October/November 2013) at Control and Impact sites (data pooled for sites and assemblages). Net percentage change calculated for Impact Control 19 p-values from the F-tests for linear regression between net sedimentation and change in canopy cover (%) for each assemblage for D5 (October/November 2013) 20 Table 4-5 Mean seedling and sapling densities (per m 2 ± SE) recorded during B2 (July/August 2012) and D5 (October/November 2013) at Control and Impact sites in the four mangrove assemblages. Change in density (D5 -B2) is indicated, with a decline denoted by a minus sign (-) 21 Table 4-6 Table 4-7 Table 4-8 Table 4-9 Total mean (± SE) seedling and sapling species richness per quadrat recorded during B2 (July/August 2012) and D5 (October/November 2013) for Control and Impact treatments, for the four mangrove assemblages 24 Mean (± SE) number of individual seedlings per quadrat for Control and Impact sites recorded during B2 (July/August 2012) and D5 (October/November 2013), and percentage survival from B2 to D5 25 Summary of mean seedling survival since B2 (July/August 2012) at Control and Impact sites (data pooled for sites and assemblages), and survival calculated for Impact Control 27 p-values from the F-tests for linear regression between net sedimentation and percentage change in seedling survival for each assemblage for D5 (October/November 2013) 27 Table 4-10 Mean (± SE) leaf counts per individual seedling and mean percentage leaf change per permanent quadrat (± SE) by assemblage from Control and Impact sites during B2 (July/August 2012) and D5 (October/November 2013) 29 Table 4-11 Mean (±SE) percentage change in seedling leaf numbers between B2 (July/August 2012) and D5 (October/November 2013), expressed as % of B2 at Control and Impact sites (data pooled for sites and assemblages). Net percentage change calculated for Impact Control 31 Table 4-12 The p-values from the F-tests for linear regression between net sedimentation and change in number of leaves (%/plant) for each assemblage for D5 (October/November 2013) 32 Table 4-13 Mean (±SE) number of nodes per seedling and percentage change in nodes between B2 (July/August 2012) and D5 (October/November 2013), expressed as % of B2 at Control and Impact sites (data pooled for sites and assemblages). Net percentage change calculated for Impact Control 33 Table 4-14 Mean (± SE) percentage change in number of nodes on seedlings at Control and Impact sites (data pooled for sites and assemblages) and net percentage change calculated for Impact Control 35 Table 4-15 The p-values from the F-tests for linear regression between net sedimentation and change in number of nodes for each assemblage for D5 (October/November 2013) 36 Prepared for INPEX Cardno Page viii

9 Table 4-16 Total number of fauna species and individuals (in parentheses) for each taxonomic group recorded during B1, B2, D1, D2, D3 and D5. B1 and B2 (pooled) for the four mangrove assemblages at Control and Impact sites. The overall species richness and percentage of records for all surveys to date are also indicated. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013). * Abundance was not recorded for ants 38 Table 4-17 New taxonomic records for species sampled during D5 (October/November 2013) 39 Table 4-18 Mean (± SE) total fauna species richness per sampling station for B1, B2, D1, D2, D3 and D5 for Control and Impact sites in the four mangrove assemblages. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) 39 Table 4-19 Mean total fauna abundance (± SE) per sampling station for B1, B2, D1, D2, D3 and D5 for Control and Impact sites in the four mangrove assemblages. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) 41 Figures Figure 2-1 Location of Control sites (blue) and Impact sites (red) for the ISMCHMP 6 Figure 2-2 Schematic profile diagram of the typical pattern of assemblages from landward (left) to seaward (right) observed in Darwin Harbour mangroves. Source: Metcalfe (2007) 7 Figure 2-3 Typical layout of transect from landward to seaward with mangrove health monitoring plots (20 m x 20 m) in each of the four main assemblages in relation to the intertidal sedimentation monitoring stations and remote sensing site extent (see Cardno and EcoScience NT 2012, Cardno 2013b and Cardno 2013c for additional details) 7 Figure 2-4 Schematic representation of a) mangrove monitoring plots indicating the number and location of replicate sampling stations and 1 m x 1 m quadrats for different indicators of mangrove health. The representative position of b) the sedimentation monitoring array (data used in regression analyses) is also shown. 8 Figure 3-1 East Arm dredging footprint 14 Figure 4-1 Mean percentage canopy cover (± SE) in the four assemblages from landward to seaward recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison with the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013) 17 Figure 4-2 Mean change in canopy cover (% ± SE) between B2 (July/August 2012) and D5 (October/November 2013) in the four assemblages from landward to seaward at Control and Impact sites 19 Figure 4-3 Net sedimentation (mm) versus change in canopy cover (%) during D5 (October/November 2013) for each assemblage. Each point represents the average for site within an assemblage. Impact sites are red and Control sites are blue 20 Figure 4-4 Mean (± SE) seedling density in the four assemblages from landward to seaward recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison with the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013) 22 Figure 4-5 Mean (± SE) change in seedling density between B2 (July/August 2012) and D5 (October/November 2013) in the four assemblages from landward to seaward at Control and Impact sites 23 Prepared for INPEX Cardno Page ix

10 Figure 4-6 Mean (± SE) percentage survival of individual seedlings from B2 (July/August 2012) to D5 (October/November 2013) in the four assemblages from landward to seaward recorded at Control and Impact sites 25 Figure 4-7 Mean (± SE) percentage survival of individual seedlings in the four assemblages from landward to seaward recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison with the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013) 26 Figure 4-8 Net sedimentation (mm) versus percentage change in seedling survival at D5 (October/November 2013) for each assemblage. Each point represents the average for site within an assemblage. Impact sites are red and Control sites are blue 28 Figure 4-9 Mean (± SE) number of leaves per plant on individual seedlings in the four assemblages from landward to seaward recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison with the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013) 30 Figure 4-10 Mean (± SE) percentage of change in the number of leaves of seedlings between B2 (July/August 2012) and D5 (October/November 2013) in the four assemblages from landward to seaward at Control and Impact sites 31 Figure 4-11 Net sedimentation (mm) versus change in number of leaves (% per plant) during D5 (October/November 2013) for each assemblage. Each point represents the average for site within an assemblage. Impact sites are red and Control sites are blue 32 Figure 4-12 Mean (± SE) number of nodes per individual Rhizophoraceae seedling in the Hinterland Margin, Tidal Flat and Tidal Creek assemblages recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison to the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013). No Seaward assemblage data available as there were no suitable species present (i.e. Rhizophoraceae) 34 Figure 4-13 Mean (±SE) percentage change in the number of nodes per individual Rhizophoraceae seedling from B2 (July/August 2012) to D5 (October/November 2013) in three of the four assemblages from landward to seaward at Control and Impact sites. No Seaward assemblage data available as there were no suitable species present (i.e. Rhizophoraceae) 35 Figure 4-14 Net sedimentation (mm) versus percentage change in number of nodes (per cent per plant) at D5 (October/November 2013) for each assemblage. Each point represents a site, which is labelled to the left or above. Impact sites are red and Control sites are blue 36 Figure 4-15 Mean (± SE) total fauna species richness in the four assemblages from landward to seaward recorded during B1, B2, D1, D2, D3 and D5. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) 40 Figure 4-16 Mean total fauna abundance (±SE) in the four main assemblages from landward to seaward recorded during B1, B2, D1, D2, D3 and D5. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) 42 Figure 4-17 Ordination of sampling stations at Control (grey) and Impact (blue) sites during B1 (upward triangles), B2 (downward triangles), D1 (open circles), D2 (closed circles), D3 (open squares) and D5 (closed squares) based on presence/absence of fauna species. Data were pooled for all sampling methods per station in each of the four assemblages 43 Figure 4-18 Ordination of sampling stations sampled during B1, B2, D1, D2, D3 and D5 in the four assemblages based on the presence/absence of fauna species. Data were pooled for all sampling methods used per station. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) 44 Figure 4-19 Ordination of sampling stations sampled during dry (green) and wet (blue) season based on the presence/absence of fauna species. Data were pooled for each sampling method for dry and wet season surveys (B1, B2, D1, D2, D3 and D5). B1 (June 2012), B2 (July/August Prepared for INPEX Cardno Page x

11 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) 44 Figure 5-1 Three of the nine new taxonomic records sampled in Darwin Harbour mangrove during the D5 survey: A) Psedoliotia sp. 2 B) Mysidacea sp.; and C) Penaeidae sp. 48 Appendices Appendix A Intertidal Sedimentation and Mangrove Health Trigger Action Response Plan 53 Appendix B Method Details 56 Appendix C Time Series Results by Assemblage/Site 61 Appendix D Statistical Analyses Flora 87 Appendix E Photo Monitoring 99 Appendix F Fauna Results 120 Appendix G Statistical Analysis Fauna 146 Prepared for INPEX Cardno Page xi

12 1 Introduction 1.1 Background INPEX is the operator of the Ichthys Gas Field Development Project (the Project). The Project comprises the development of offshore production facilities at the Ichthys Field in the Browse Basin, some 820 km west-south-west of Darwin, an 889 km long subsea gas export pipeline (GEP) and an onshore processing facility and product loading jetty at Blaydin Point on Middle Arm Peninsula in Darwin Harbour. To support the nearshore infrastructure at Blaydin Point, dredging works will be carried out to extend safe shipping access from near East Arm Wharf to the new product loading facilities at Blaydin Point which will be supported by piles driven into the sediment. A trench will also be dredged to seat and protect the GEP for the Darwin Harbour portion of its total length. Dredged material will be disposed at the spoil ground located approximately 12 km north-west of Lee Point. A detailed description of the dredging and spoil disposal methodology is provided in Section 2 of the East Arm (EA) Dredging and Spoil Disposal Management Plan (DSDMP) (INPEX 2012) and GEP DSDMP (INPEX 2013a). 1.2 Requirement to Monitor Mangrove Health Mangrove ecosystems are valued globally for their important ecological and economic values. The intertidal areas between Tapa Bay to the west and Shoal Bay to the east of Darwin contain over 33,000 hectares (ha) of mangroves (Cardno 2013b). In addition to being one of the largest discrete blocks of mangroves in the Northern Territory, this area is recognised for its diversity, containing over 30 species of mangrove flora (McGuinness 2003; Wightman 2006). The Draft Environmental Impact Statement (EIS) (INPEX 2011) identified potential indirect impacts on mangroves from dredging generated sedimentation in intertidal areas in Darwin Harbour. Excess deposition of sediment to mangrove communities can cause tree stress owing to smothering and burial of root systems. Impacts can range from reduced vigour to death, depending on the amount and type of sedimentation and the mangrove species involved. Ellison (1998) noted that there are insufficient data available to establish specific tolerances; however, it is considered that sedimentation levels of up to 50 mm would be generally tolerated by seaward mangrove communities throughout East Arm (INPEX 2011). For the purposes of impact predictions and reactive management trigger values, sensitive mangrove genera (e.g. Sonneratia, Ceriops and Avicennia) were considered to be at risk of reduced plant health or growth at net deposition of less than 50 mm and tree mortality was considered likely to occur at net sedimentation rates of 50 mm or greater (INPEX 2011). The level of response and rates of recovery are likely to depend on several factors such as the timing, duration, intensity and scale of the dredging works, and resultant sedimentation. Modelling of the continuous (year-round) dredging scenario estimated that 42 ha of mangroves could be affected by sedimentation of 50 mm or more. The Intertidal Sedimentation and Mangrove Community Health Monitoring Program (ISMCHMP) has been designed to test modelled predictions and allow an opportunity to respond in order to manage impacts beyond those predicted. The program focuses on detection of potential impacts from dredging on mangroves within East Arm, using Control sites located inside Darwin Harbour (i.e. Middle Arm) but outside East Arm. Detailed mapping and classification of Darwin Harbour mangrove assemblages using multispectral satellite imagery has been carried out by Brocklehurst and Edmeades (1996), and the assemblage categories, zone numbering and naming conventions used in that study were adopted for this monitoring program. 1.3 Results of Baseline Phase Surveys Two Baseline Phase surveys (B1: June 2012 to July 2012 and B2: July 2012 to August 2012) of mangrove flora and fauna were completed during three months from June 2012 to August 2012 (Cardno and EcoScience NT 2012). Mangrove Community Health was monitored using key flora indicators comprising canopy cover, seedling and sapling density, and seedling growth and survival, while fauna Prepared for INPEX Cardno Page 1

13 was characterised by documenting species richness, abundance and composition. Mangrove fauna was sampled in B1, B2 and all surveys except D4 (July 2013) as this component of monitoring formed part of the reduction of the scope of the NEMP for the dry season (INPEX 2013b). Canopy cover between B1 and B2 (July/August 2012) was similar (overall mean 80.8% ± 1.0 SE and 80.5% ± 1.1 SE) with very little variability among sites. Canopy cover at Control sites was representative of Impact sites and hence considered suitable for comparison during dredging operations. Across the intertidal area, seedling density was generally greatest in the Seaward and Tidal Flat assemblages, and least in the Tidal Creek and Hinterland Margin, and this pattern was fairly consistent between Control and Impact sites. By contrast, there were fewer saplings in the Seaward and Tidal Flat than in the other assemblages. With the exception of the Tidal Flat, there were generally low densities of saplings relative to seedlings, indicating that few seedlings survive to the sapling stage. Baseline Phase data revealed overall patterns in seedling growth and survival were similar among the sites, but differences were evident between assemblages. Leaf counts were consistently higher at Control sites than at Impact sites during B1 and B2 (July/August 2012); however, this was an inherent difference and, overall, Control sites were representative of Impact sites. Trends across the intertidal area showed that growth and survival generally increased in a seaward direction (e.g. leaf and node growth was greatest in the Tidal Creek) and variability was more pronounced in the landward assemblages. Seedling survival in the Hinterland Margin was lowest and most varied, with leaf change varying over time (i.e. plants lost and grew leaves) and between sites. Although leaf growth was greatest in the Seaward assemblage, seedling mortality was also greatest. Photo-monitoring provided context for flora indicators and a benchmark for future monitoring during the Dredging and Post-dredging Phases of the Project. The combined Baseline Phase methodologies provided a good understanding of temporal and spatial variability at the ten monitoring sites. 1.4 Objectives The ISMCHMP comprises three sub-programs: 1. Intertidal Sedimentation; 2. Mangrove Community Health; and 3. Remote Sensing of mangrove forests. Table 1-1 presents the techniques used and indicators for each sub-program, outlining whether they are reactive or informative. Reactive indicators are used as triggers to implement further monitoring or a management response, as outlined in the EA DSDMP (INPEX 2012) and GEP DSDMP (INPEX 2013a). Data collected on informative indicators are used for interpretative purposes to assist in the attribution of potential causes using a multiple lines of evidence approach and to support management responses if reactive triggers are exceeded during dredging and spoil disposal activities. The DSDMPs include a Trigger Action Response Plan (TARP) in which sedimentation and mangrove health trigger values are prescribed. A summary of the TARP trigger values methods of determination is provided in Table 1-1 and the TARP is presented in Appendix A. The objectives of the ISMCHMP are to: > Detect accretion of sediment within intertidal mangrove areas attributable to dredging in East Arm; > Detect changes in mangrove health (including mangrove associated faunal communities) attributable to dredging in East Arm; and > Provide appropriate data to allow clear and timely determination of exceedances of management trigger levels. During the Dredging Phase, a Before-After Control-Impact (BACI) design will be used to assess the significance of monitoring results at Impact sites against Baseline Phase data and Control sites. The objectives of the Mangrove Community Health (MCH) component of the ISMCHMP are to: Prepared for INPEX Cardno Page 2

14 > Provide monitoring results for quarterly surveys conducted during dredging for both reactive and informative indicators; > Analyse results by comparison of Control and Impact sites monitored during Dredging Phase surveys; and > Compare Baseline Phase results with Dredging Phase data and assess changes in reactive and informative indicators. This report presents MCH monitoring data for Dredging survey 5 (D5), undertaken in October and November It addresses the above objectives related to the MCH component of the ISMCHMP; other components (Intertidal Sedimentation and Remote Sensing) are reported separately. Table 1-1 Overview of ISMCHMP monitoring methods and indicators Method Indicator Reactive or Informative Mangrove Community Health Monitoring* Mangrove flora Mangrove fauna surveys Remote Sensing of Mangroves*** High resolution satellite imagery Canopy cover Seedling survival and growth Leaf litter fall (including stipule counts)** Seedling and sapling density and recruitment Photo-monitoring Benthic fauna Epifauna Infauna Refuge pools and free-ranging fauna Fish Normalised Difference Vegetation Index (NDVI) Reactive (Level 2 trigger) Informative Informative Reactive (Level 3 trigger) Intertidal Sedimentation Monitoring**** Sediment stakes Sedimentation levels Reactive (Level 1 / 2 trigger) Sediment characterisation ph Particle size distribution Informative * Mangrove fauna was not sampled in D4 (July 2013) as this component of monitoring formed part of the dry season reduction to the scope of the NEMP (INPEX 2013b). ** Methods and results provided in the Primary Productivity Reports. *** Methods and results provided in Remote Sensing Reports. **** Methods and results provided in Intertidal Sedimentation Reports. Prepared for INPEX Cardno Page 3

15 2 Methodology A summary of the MCH monitoring methodology is provided below; for full details refer to the Mangrove Community Health Monitoring Program Baseline Report (Cardno and EcoScience NT 2012) and Appendix A of the Nearshore Environmental Monitoring Plan (NEMP) (Cardno 2013a). 2.1 Survey Timing The survey dates for the MCH program are presented in Table 2-1, as well as linkages between the MCH surveys and other components of the ISMCHMP. Two Baseline Phase surveys (B1 and B2) were completed during three months from June 2012 to August Three routine quarterly monitoring surveys (D1 to D3) were carried out during the 2012/2013 wet season covering the duration of Season One dredging, which commenced on 27 August 2012 and ceased on 30 April The results presented in this report refer to D5 (October/November 2013) MCH monitoring, following a maximum of 19 days of dredging, which commenced for the GEP on 23 October 2013 and recommenced at East Arm on 1 November Completion of surveys in four mangrove assemblages located between the landward margin and the seaward fringe is heavily tide-dependent and each monitoring survey is normally split into two 10-day blocks (e.g. B1a and B1b, D1a and D1b). These coincide with spring tidal cycles to ensure sites are exposed for a sufficient time during low tide to complete sampling. As faunal sampling was removed from the D4 (July 2013) survey, routine monitoring was conducted in only one ten-day block; dates and sites for D5 are provided in Table 2-2. Table 2-1 Survey Name Baseline 0 (Site Establishment) Summary of ISMCHMP survey dates Survey Code B0 Remote Sensing Baseline 1 B1 14 July 2012 to 28 July 2012 (5 different days) Baseline 2 B2 No B2 (July/August 2012) Dredging 1 D1 2 November 2012 to 27 November 2012 (3 different days) Dredging 2 D2 No D2 no data acquisition possible due to cloud cover Dredging 3 D3 25 April 2013 (1 day) Dredging 4 D4 15 July 2013 (1 day) Dredging 5 D5 13 October 2013 and 1 November 2013 (2 different days) ISMCHMP Component Date Intertidal Sedimentation 18 May 2012 to 28 May June 2012 to 27 June July 2012 to 27 July October 2012 to 21 October January 2013 to 16 January April 2013 to 14 April July 2013 to 16 July October 2013 to 10 October 2013 Mangrove Community Health 18 May 2012 to 28 May June 2012 to 27 June July 2012 to 11 August October 2012 to 22 November January 2013 to 17 February April 2013 to 17 May July 2013 to 31 July 2013 (Flora only) 17 October 2013 to 11 November 2013 Prepared for INPEX Cardno Page 4

16 Table 2-2 Field sampling dates for MCH monitoring during D5 Site Location D5 I1 Bayview October 2013 C3 Middle Arm October 2013 I5 Elizabeth River - Creek October 2013 I2 Bleesers Creek October 2013 C4 Blackmore River Boat ramp October 2013 I4 Lightning Creek (Blaydin Point) 1-2 November 2013 C2 Channel Island, East 3-4 November 2013 I3 East Arm Boat ramp 5-6 November 2013 I6 Elizabeth River - Upstream 7-8 November 2013 C1 Talc Head 9-10 November Sampling Design The key indicators for MCH monitoring comprise: > Canopy cover in 20 m x 20 m plots and remote sensing vegetation index data; > Seedling survivorship and growth from permanent 1 m x 1 m quadrats; > Seedling and sapling density and recruitment from randomly placed 1 m x 1 m quadrats; and > Mangrove fauna total species richness and total abundance (pooled from sampling of benthic fauna, epifauna, infauna, fauna in refuge pools, fish and ants) using a number of different methods Sites Six Impact sites (also termed Locations in Section 3) were selected on the basis of modelling results to coincide with those areas that were predicted to receive the maximum levels of sedimentation (i.e. >50 mm) from dredging operations in the East Arm of Darwin Harbour. Four Control sites were selected outside of East Arm at sites that were not predicted to receive sediment from dredging operations (Table 2-3, Figure 2-1). A complete list of GPS co-ordinates for the ten sites can be found in Appendix A-2 of the Mangrove Community Health Monitoring Baseline Report (Cardno and EcoScience 2012). Table 2-3 MCH Monitoring Sites Pairing of Control and Impact sites in table indicates similarities in geomorphic setting and harbour position Impact Site Site Code Control Site Site Code Sadgroves Creek I1 Talc Head/Woods Inlet C1 Bleesers Creek East Arm Boat Ramp Lightning Creek Elizabeth River - Creek I2 I3 I4 I5 East Channel Island Middle Arm Upper Elizabeth River I6 Blackmore River Boat Ramp C4 C2 C3 Prepared for INPEX Cardno Page 5

17 Figure 2-1 Location of Control sites (blue) and Impact sites (red) for the ISMCHMP Prepared for INPEX Cardno Page 6

18 2.2.2 Assemblages, Plots and Transects Twelve distinct intertidal communities have been defined and mapped in Darwin Harbour (termed assemblages/zones by Brocklehurst and Edmeades (1996)), with four of these accounting for approximately 80% of the total mangrove area. The pattern of zonation generally evident in Darwin Harbour and the relationship between these assemblages and tidal elevation is shown in Figure 2-2. Monitoring plots were placed in each of the four main mangrove assemblages shown in Figure 2-2. At each monitoring site, a transect was established from landward to seaward (Figure 2-3). Apart from the two most upstream sites (C4 and I6), which lack a Seaward assemblage, permanent 20 m x 20 m monitoring plots were established in each of the four main assemblages (Figure 2-4). Sedimentation monitoring stations were established in the vicinity of each plot, at a comparable tidal position, and immediately adjacent where possible (Figure 2-2, Figure 2-4). Each mangrove health plot was divided equally into four 10 x 10 m subplots, formed by the four plot corners and the centre point (Figure 2-4). Figure 2-2 Schematic profile diagram of the typical pattern of assemblages from landward (left) to seaward (right) observed in Darwin Harbour mangroves. Source: Metcalfe (2007) Figure 2-3 Typical layout of transect from landward to seaward with mangrove health monitoring plots (20 m x 20 m) in each of the four main assemblages in relation to the intertidal sedimentation monitoring stations and remote sensing site extent (see Cardno and EcoScience NT 2012, Cardno 2013b and Cardno 2013c for additional details) Prepared for INPEX Cardno Page 7

19 Figure 2-4 Schematic representation of a) mangrove monitoring plots indicating the number and location of replicate sampling stations and 1 m x 1 m quadrats for different indicators of mangrove health. The representative position of b) the sedimentation monitoring array (data used in regression analyses) is also shown At several sites, the width of existing mangrove communities was not sufficient to encompass plots 20 m x 20 m in size. At two sites (I2 and I4), plot dimensions in the Seaward assemblage were modified to 10 m x 40 m, while maintaining the same 400 m 2 area as the standard-sized (20 m x 20 m) plots. Aerial imagery of each plot is provided in the Remote Sensing Baseline Report (Cardno 2013c). 2.3 Field Methodology Canopy Cover Canopy cover is a useful indicator of mangrove health, since leaf shedding and leaf growth are sensitive to a wide range of environmental factors. Changes in canopy or foliage cover may be indicative of environmental stress. Within each monitoring plot, forest canopy cover was measured using a tripod-mounted Stickler s modified (17-point) spherical forestry densiometer (Stickler 1959) to provide estimates of the foliage cover (combined leaf and branch cover). Three replicate canopy cover measurements were taken from within each of the four 10 m x 10 m subplots (Figure 2-4). Each measurement involved readings at a randomly selected point (located using random number tables), whilst facing north, east, south and west providing a total of 48 readings per plot Seedling and Sapling Density, Recruitment and Species Richness The density of the overall population of seedlings and saplings within each monitoring plot was estimated from counts of seedlings and saplings (by species) within 1 m x 1 m replicate quadrats. Species richness was also measured. Two replicate quadrats were placed at randomly selected points (located using random number tables) in each of the four 10 m x 10 m subplots (Figure 2-4). These data allow forest regeneration Prepared for INPEX Cardno Page 8

20 to be monitored by comparing seedling densities from B2 (July/August 2012) with densities in the Dredging and Post-dredging Phases Seedling Survival and Growth Individually identified and numbered seedlings within five permanent 1 m x 1 m quadrats per plot were monitored to measure their survival and growth. Seedlings were defined as plants <1 m tall and <20 mm girth. Mature, but small, plants (such as the shrub Aegialitis annulata or stunted Ceriops australis) were excluded. Mangrove seedlings are too delicate to be tagged; therefore, in order to facilitate repeated measures of the same individual seedlings in the quadrats, individual seedlings surviving since B2 (July/August 2012) were identified with aid of diagrams of each of the five 1 m 2 quadrats that included the precise locations of each seedling. New recruits were also recorded and added to subsequent diagrams, but not included in analyses (see Section 2.4.1). The orientation of each quadrat, and hence the accurate relocation of individual seedlings, was facilitated by numbered and labelled quadrat corner posts. Due to the characteristically sparse and patchy distribution of mangrove seedlings, particularly in areas of dense forest, permanent 1 m x 1 m quadrats were selectively placed in areas where seedlings were present Seedling Survival Monitoring of seedling survival entailed counting seedlings that survived, or senesced, in the permanent 1 m x 1 m quadrats. These data were then used to calculate percentage survival of seedlings (in any survey) since the Baseline Phase Total Leaf Counts Counts of the total number of leaves (and nodes, see below) on individual seedlings within the permanent 1 m x 1 m quadrats were used as a proxy for monitoring seedling growth Total Node Counts As for leaves, counts of the total number of nodes on individual seedlings occurring within the permanent 1 m x 1 m quadrats were used as a proxy for monitoring seedling growth. Mangrove seedlings of species in the Rhizophoraceae family possess opposite leaves and when these are shed during active growth a visible leaf scar (or node) persists on the main stem and on lateral branches. However, other common mangrove species, including Avicennia marina, Excoecaria ovalis, Sonneratia alba and Aegiceras corniculatum, do not produce clear leaf scars or nodes. Therefore, only seedlings of Rhizophoraceae species (including Rhizophora stylosa, Ceriops australis, Ceriops decandra, Bruguiera exaristata and Bruguiera parviflora) are amenable to monitoring growth by recording the increase in node counts on the main stem (node gain per unit time). By contrast, growth of all species of mangrove can be assessed by leaf counts. The dense growth of algae on the stem of some seedlings precluded accurate measurement of leaf nodes in some individuals. These seedlings were excluded from the program, as were plants with secondary thickening and swelling of the stem with age, as this substantially reduced the accuracy of counting nodes. Dense algal growth on seedlings precluding node counts occurred only in the Seaward assemblage and mainly affected only one species (Aegiceras corniculatum), the dominant seedling species in this habitat, so only leaf counts were used to monitor growth in this species Photo-monitoring Four digital photographs were taken within each of the 38 monitoring plots for reference and to monitor mangrove health by detecting potential changes in physiognomy, forest health, vegetation structure, regeneration and species composition over time. The centre of each 20 m x 20 m monitoring plot, (marked by a permanent PVC post) functioned as the central point from which four photographs (landscape format) were taken during each routine monitoring survey (Figure 2-4). The photographer stood at the centre post whilst the camera was directed toward one of the four corners of each 20 m x 20 m plot. Four PVC photomonitoring posts were located on the diagonal of each plot at a distance of 3 m from the centre to assist in the accurate relocation of photo-points. A site marker board was placed on these posts to indicate the site ID code, date and the corner number of each quadrant being photographed (e.g. C36-1, C36-2 etc.). Photos from the most recent survey were compiled and compared with those from B1 and examined for any negative changes in physiognomy and forest health potentially indicating sedimentation impacts from dredging. Negative changes in forest health might be indicated for example, by yellowing, wilting and loss of Prepared for INPEX Cardno Page 9

21 leaves, reduced vigour and abundance of seedling/sapling populations, shedding of branches and tree death Fauna A composite field methodology developed specifically to document faunal biodiversity (Metcalfe 2007) was used to record the richness and abundance of each of the main macro-invertebrate groups and small resident fish found in mangroves. All molluscs, crustaceans, worms and ants (large enough to be visible to the naked eye) were monitored. Within each monitoring plot, fauna were sampled at three randomly selected sampling stations through various methods. For a detailed description of the methodology for sampling fauna, see Mangrove Community Health Monitoring Program Baseline Report (Cardno and EcoScience NT 2012). 2.4 Statistical Analyses and Trigger Tests Flora data were analysed using a range of descriptive, inferential, univariate and multivariate techniques Flora Indicators All raw data for flora were entered into a spreadsheet and prepared for tabulation or analyses in the Project Biological Database. A summary of indicators and metrics derived from the data is provided in Appendix B- 1. Details are provided on the level of replication and grouping of data for the calculation of the metrics. It is important to note that, since there was only one plot per assemblage at each site, plot averages are the same as assemblage averages. It is also important to note at which stage of the metric calculation conversion to percentage is performed to ensure that the metrics are comparable among surveys. For analysis of seedling growth (i.e. counts of leaves or nodes), species recorded in fewer than 10% of plots from the total dataset were excluded from statistical analyses. For counts of leaves, the species included were: Aegiceras corniculatum, Rhizophora stylosa, Bruguiera parviflora and Ceriops australis. Counts of nodes were also undertaken for these species apart from Bruguiera exaristata which was excluded from analyses due to insufficient numbers of seedlings Fauna Indicators Raw data for fauna were entered into a Microsoft Access database and then transferred to Excel, from which appropriate tables were compiled for different analyses (e.g. generation of site by species matrices). Raw data were examined to identify records of organisms not representing a taxonomically distinct entity or not identified as a species (e.g. records for immature crab, immature Perisesarma, Uca unidentified etc.). By convention, the species richness analyses excluded individuals of uncertain species status. By contrast, faunal abundance data included all organisms, including immature and unidentified taxa with the exception of the actual number of ants, which are represented by a presence/absence record (i.e. abundance = 1). Summary statistics were calculated in either Excel or MINITAB Release for Windows Statistical Design and Analysis of Variance The majority of statistical analyses were carried out using Primer 6 (version ) and PERMANOVA+ software (version 1.0.5) (Primer-E Ltd). Factors included in the analyses were: > Phase Fixed and orthogonal with two levels (Baseline and Dredging); > Survey Random and nested within Phase with seven Levels (two Baseline and five Dredging); > Treatment Fixed and orthogonal with two levels (Impact and Control); > Location Random and nested within Treatment with ten levels (six Impact, four Control); and > Assemblage - Fixed and orthogonal with four levels (Hinterland Margin, Tidal Flat, Tidal Creek, Seaward). Differences in flora indicators (canopy cover, seedling and sapling density) were tested using a five factor mixed model Analysis of Variance (ANOVA) in a Before-After Control-Impact (MBACI) framework. For the period between B2 and D5, statistical analysis of seedling survival (all species combined) and growth (i.e. leaf and node counts for all species combined, and for species found in more than one assemblage) Prepared for INPEX Cardno Page 10

22 comprised a three factor nested PERMANOVA with the factors: Treatment, Location (Site) and Assemblage. For individual species found in one assemblage only, analyses involved only two factors (Treatment and Location). In each of these analyses, no temporal factors (i.e. Phase or Survey) were included because of the potential for auto-correlation of the data (i.e. the temporal effect was assessed by calculating the change between B2 and D5. ANOVAs were undertaken in PERMANOVA+ using Euclidean distance resemblance matrices. All default PERMANOVA+ options were used including maximum (9999) permutations (Anderson et al. 2008). Post-hoc permutational t-tests were undertaken, where required, to aid in the interpretation of significant results. Differences in total fauna species richness and total fauna abundance were tested using a mixed model PERMANOVA (i.e. using the nested design outlined above), and were based on Euclidean distance resemblance matrices. All default PERMANOVA+ software options were used, with the exception of number of permutations (maximum permutations = 9999) (Anderson et al. 2008). Post-hoc permutational t-tests were performed, where required, to aid in the interpretation of significant PERMANOVA results Faunal community composition analysis Assessment of mangrove fauna community composition was carried out in Primer 6. Sites with a species richness less than two and species recorded on fewer than two sites were excluded from analyses. Species composition was represented as either presence/absence or the raw abundance of each species. Nonmetric multidimensional scaling (nmds) based on a Bray-Curtis dissimilarity index was used to analyse untransformed data and each analysis was run from 50 random restarts. Ordinations were used to examine the data for patterns (where each sample site was described by the species richness and/or abundances of the species present) and to present this information in graphs. Points positioned close together on nmds ordinations represent sites that are very similar in fauna species composition, and points that are far apart correspond to very different fauna communities. Differences in fauna composition were tested using the same mixed model PERMANOVA as described for richness and abundance. The Bray-Curtis dissimilarity index was used along with default PERMANOVA options (except number of permutation = 9999). Post-hoc permutational t-tests were performed, where required, to aid in the interpretation of significant PERMANOVA results Assessment against Trigger Values Three mangrove health indicators (canopy cover and seedling growth and survival) were defined as Level 2 triggers in the TARP (Appendix A) and net change in these were tested in relation to trigger levels. Net change in canopy cover, seedling survivorship and growth were determined by calculating the difference between Impact and Control treatments for D5 and B2 (data pooled for sites and assemblages). Trigger tests were performed in two steps. Firstly, differences between Control and Impact sites were analysed using standard t-tests for two independent samples; however, to test the assumption of equality of variances, prior F-tests were undertaken and the appropriate t-test selected based on the results (i.e. students t-test for equal variances; Welch s t-test for unequal variances). If t-tests showed that significant differences were found between Control and Impact sites, the second step of the trigger assessment was undertaken. This step involved doing another t-test with the hypothesised mean difference between Control and Impact sites of the set trigger values. A trigger was considered to have been exceeded if the difference between Control and Impact sites was statistically significant and if the mean difference did not differ significantly from the set trigger value Relationships between Flora Indicators and Intertidal Sedimentation Regression analyses were used to investigate the potential effects of the intertidal sedimentation impact pathway. The analyses involved a comparison of net sedimentation during D5 (October/November 2013) at each site and assemblage, with the key flora indicators (change in canopy cover, seedling growth (leaf and nodal change) and survival) during D5. Net sedimentation was used as the independent variable and the key flora indicators as the dependent variables. As mangroves may exhibit slow response rates to non-acute stresses (i.e. there may be a delay of up to a year before trees show signs of impact (Norm Duke (2012), pers. comm.)), net sedimentation was considered to be the most appropriate of the sedimentation measures for investigation of relationships with mangrove health, given it is a cumulative measure. Relationships are considered significant where p-values for regressions are less than Prepared for INPEX Cardno Page 11

23 2.5 Quality Control Collection of Field Data Field data quality control was carried out as per methods detailed in Section 2.4 of the Mangrove Community Health Monitoring Program Baseline Report (Cardno and EcoScience NT 2012). To minimise errors in recording both seedling position and leaf and node numbers, data were recorded by the same scientist during all field surveys. Where any confusion in seedling location or plant species occurred within plots, those seedlings were noted and omitted from analyses Data Management and Analyses Raw data were entered into Excel files or directly into the EcoScience NT database. Raw data entered into the spread sheets were checked both during entry to the database and subsequently by a second scientist prior to analysis and any discrepancies checked against the raw data or master species list for verification. The raw data were then uploaded to the Project SQL database where a number of automated data completeness and quality checks were carried out. Data are corrected where necessary, and descriptive statistics are generated. A QAQC checked data file is generated for use in statistical software. All analytical outputs were saved and checked by a senior environmental scientist and any changes to original analyses were saved as different versions to ensure overwrites did not occur. File management was documented by sequential recording of file names in a flow chart detailing the title and location of all files and the sequence of all analyses performed. All data were regularly backed up to write-protected dedicated portable USB storage devices with duplicate external sources in more than one location. Scanned raw data sheets, photo-monitoring images and data files are further saved in Autodesk Vault, with additional backups made onto write-protected dedicated portable USB storage devices. Prepared for INPEX Cardno Page 12

24 3 Dredging Operations The dredging program involves a number of dredge vessels including Backhoe Dredgers (BHD), Cutter Suction Dredger (CSD) and Trailing Suction Hopper Dredgers (TSHD), operating in different areas depending on water depths, bed material characteristics and the amount of material to be removed. The East Arm dredging campaign is divided into five Separable Portions (SP1 to SP5) that refer to the location within the dredge footprint and duration of specific dredging activities. The SPs are summarised in Table 3-1 and presented in Figure 3-1. Dredging for the GEP commenced on 23 October 2013 with direct TSHD, Queen of the Netherlands. During the reporting period, TSHD operations of high spots and pipeline channel dredging occurred along the GEP route between Mandorah and Weed Reef. East Arm dredging operations recommenced on 1 November 2013 with CSD in SP5 after being temporarily suspended in the six months since 30 April As of 10 November 2013, overall East Arm progress was approximately 43% of the proposed total to be removed during the dredging program. Table 3-1 ID SP1 SP2 SP3 SP4 SP5 East Arm dredge footprint summary Separable Portion Separable Portion 1 - Module Offloading Facility (MOF) Separable Portion 2 - Jetty Pocket Separable Portion 3 - Berth Area Separable Portion 4 - Approach Channel, Berth Approach and Turning Area Separable Portion 5 - Walker Shoal Prepared for INPEX Cardno Page 13

25 Figure 3-1 East Arm dredging footprint Prepared for INPEX Cardno Page 14

26 4 Results 4.1 Flora Results Canopy Cover During D5 (October/ November 2013), canopy cover in assemblages (averaged across all sites) ranged from 77.1% ± 1.0 SE to 95.7% ± 0.3 SE (Table 4-1). Similar to the patterns observed during all previous surveys, during D5, canopy cover was greatest in the Tidal Creek and Hinterland Margin assemblages (95.7% ± 0.3 SE and 91.6% ± 0.4 SE, respectively). Canopy cover was intermediate in the Tidal Flat assemblage (84.8% ± 0.8 SE) and lowest in the Seaward assemblage (77.1% ± 1.0 SE). Mean canopy cover for Impact sites (sites combined) was very similar to that for Control sites (sites combined) in the Hinterland Margin and Tidal Creek assemblages, and lower for Impact sites than Control sites in the Tidal Flat and Seaward assemblages (Table 3-1). This pattern persisted from B2 (July/August 2012). For the Seaward assemblage, there was a difference in canopy cover between Control and Impact sites in B2. This difference is also present and larger in each of the five dredging surveys, but there is no clear trend of the difference becoming greater with each successive survey. During D5 there was considerable variability in mean canopy cover among Control and Impact sites for each of the assemblages, as was the case for B2 (July/August 2012) (Table 3-2). Variability was generally greatest in the Seaward assemblage. There were also no obvious consistencies in the direction or extent of change from the Baseline Phase to D5 across sites within Treatments or between Treatments. Based on pooled sites within Impact and Control treatments, the greatest change in canopy cover in any assemblage from B2 to D5 occurred in the Seaward assemblage Impact sites (-4.6% ± 1.3 SE; Table 3-1, Figure 3-2). This was influenced by Impact sites I2, I3, and I5, which all declined by approximately 10% (Table 3-2, Appendix C-1). The largest decline in canopy cover measured at Control sites was -6.7% at the Seaward Assemblage in Site C3. Changes in canopy cover from B2 to D5 at sites in the other assemblages have generally been small (i.e. <5%), apart from the Tidal Flat assemblage at Site I5, where cover declined by 11.7%. Canopy cover was significantly different between Baseline and Dredging, but only at Impact sites (main model Phase x Treatment interaction p < 0.01, Appendix D-1 A; post-hoc test for Baseline versus Dredging, Impact sites p <0.01; Appendix D-1 B). No significant difference was found between Baseline and Dredging at Control sites (p = 0.75, Appendix D-1 B, Appendix D-1 C). There was no significant difference between Control versus Impact sites in either Baseline or Dredging surveys (p = 0.75, p = 0.17, respectively, Appendix D-1 B). Results outlined above indicate that this was most likely driven by the decline in mean canopy cover recorded in D1 (October/November 2012) in the Seaward assemblage at Impact sites, which has remained evident across Dredging surveys (D2 to D5) compared with Baseline levels (Figure 3-1). However, while these reductions are large relative to changes for other assemblage/treatment combinations (e.g. Figure 3-2), the net change (-4.6% ± SE 1.3) is very small when compared with the relevant trigger value (net change >30%; Section 3.1.2) and actual canopy cover at Seaward assemblage Impact sites (74.8%) (Table 3-1). Localised significant differences in canopy cover between Locations (within Treatments) were also noted, but these were dependent on Assemblage and Phase (i.e. significant Phase x Assemblage x Location interaction, p < 0.01, Appendix D-1 A). Post-hoc pairwise test results for the significant interaction term Assemblage x Survey (Phase) are presented in Appendix D-1 D, but will not be described further due to irrelevance with respect to detection of impacts from dredging. Prepared for INPEX Cardno Page 15

27 Table 4-1 Mean percentage canopy cover (± SE) recorded during B2 (July/August 2012) and D5 (October/November 2013) for Control and Impact sites for the four mangrove assemblages Site Type Hinterland Margin Tidal Flat Tidal Creek Seaward % ± SE % ± SE % ± SE % ± SE Control B2 Impact All sites Control D5 Change (D5 - B2) Impact All sites Control Impact Prepared for INPEX Cardno Page 16

28 Figure 4-1 Mean percentage canopy cover (± SE) in the four assemblages from landward to seaward recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison with the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013) Prepared for INPEX Cardno Page 17

29 Table 4-2 Summary of mean canopy cover (± SE) recorded for each assemblage at Control and Impact sites during B2 (July/August 2012) and D5 (October/November 2013) Treatment Site Assemblage (No.) Canopy Cover B2 Canopy Cover D5 Change (%) (%) ± SE (%) ± SE D5-B2 Control C1 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) C2 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) C3 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) C4 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) N/A N/A N/A N/A N/A Impact I1 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) I2 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) I3 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) I4 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) I5 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) I6 Hinterland Margin (6) Tidal Flat (4) Tidal Creek (2) Seaward (8) N/A N/A N/A N/A N/A Prepared for INPEX Cardno Page 18

30 Figure 4-2 Mean change in canopy cover (% ± SE) between B2 (July/August 2012) and D5 (October/November 2013) in the four assemblages from landward to seaward at Control and Impact sites Level 2 Trigger Assessment Net change in canopy cover (pooled Impact pooled Control sites; assemblages combined) between D5 (October/November 2013) and B2 (July/August 2012) was, on average, 1.0% (Table 4-3), and this was statistically non-significant (p = 0.26, Appendix D-1 D). The Level 2 trigger for mangrove canopy cover (>30% net change) was therefore not exceeded during D5. Table 4-3 Mean (± SE) canopy cover change between B2 (July/August 2012) and D5 (October/November 2013) at Control and Impact sites (data pooled for sites and assemblages). Net percentage change calculated for Impact Control Control Sites (%) Impact Sites (%) Impact Sites Control Sites (%) Mean ± SE Mean ± SE Net change Mean canopy cover change (D5 -B2) Relationship between Canopy Cover and Intertidal Sedimentation Field measurements of intertidal sedimentation at monitoring sites during D5 (October 2013) have not reached levels considered to potentially impact mangrove health (i.e. >50 mm) (Cardno 2013b). There was no significant relationship between net sedimentation and percentage change in canopy cover for any of the four assemblages in D5 (p ranged between 0.46 and 0.86; Table 4-4). In general, there has been very little change (i.e. <5%) in canopy cover at all sites in the Tidal Creek and Tidal Flat assemblages, whether there was net accretion or erosion, with the exception of Tidal Flat Site I5 (Figure 4-3). Here, there was a reduction in canopy cover of 11.7% but notably, there was no accretion of sediment at this site, rather, erosion had occurred. The decline in canopy cover in the Seaward zone at Site I3 has increased over time, as has sedimentation (Cardno 2013b); however, at Site I5, the decline was greatest during D1 (October 2012) when sedimentation levels were less than 10 mm (Cardno 2013b). This suggests that there may be some sedimentation-associated impacts on mangrove health at Site I3; however, a similar magnitude of change was exhibited by Site I2, which only had 5 mm of sedimentation at D5 (Figure 3-4), and the magnitude of change is within the variability measured at many sites for the Seaward assemblage (Appendix C-1). Prepared for INPEX Cardno Page 19

31 Table 4-4 p-values from the F-tests for linear regression between net sedimentation and change in canopy cover (%) for each assemblage for D5 (October/November 2013) Assemblage p-value Tidal Creek 0.46 Tidal Flat 0.62 Hinterland Margin 0.86 Seaward 0.65 Figure 4-3 Net sedimentation (mm) versus change in canopy cover (%) during D5 (October/November 2013) for each assemblage. Each point represents the average for site within an assemblage. Impact sites are red and Control sites are blue Seedling and Sapling Density and Recruitment Seedling Density Patterns among assemblages in seedling density recorded during D5 (October/November 2013) were generally similar to those recorded during previous surveys. In D5, seedling numbers were greatest in the Tidal Flat and Seaward assemblages (sites averaged) and lowest in the Hinterland Margin and Tidal Creek (Table 4-5, Figure 3-6). Similar to previous results, the most notable decline in seedling density since B2 (July/August 2012) levels was recorded in the Seaward assemblage at Impact sites (-10.0 per m 2 ± 3.2 SE), largely due to greater seedling densities recorded at Site I4 during the Baseline Phase (Appendix C-2). At Control sites in D5, density in the Seaward assemblage was 0.2 per m 2 (± 3.7 SE) higher than in B2 (Table 3-5, Figure 4-5). In all other assemblages, seedling densities in Impact and Control treatments in D5 were on average similar to B2 (Figure 4-5). Prepared for INPEX Cardno Page 20

32 Analyses of seedling density found significant differences between some Locations, but these were dependent on Assemblage and Phase (main model Phase x Assemblage x Location interaction p < 0.01, Appendix D-2 A). There were no significant differences in seedling density in relation to the key terms of interest involving Phase and Treatment (i.e. Phase x Treatment p = 0.18; Phase x Treatment x Assemblage p = 0.98; Appendix D-2 A). Post-hoc tests were not performed as no terms of interest were found to be significant. Table 4-5 Mean seedling and sapling densities (per m 2 ± SE) recorded during B2 (July/August 2012) and D5 (October/November 2013) at Control and Impact sites in the four mangrove assemblages. Change in density (D5 -B2) is indicated, with a decline denoted by a minus sign (-) Site Type Hinterland Margin Tidal Flat Tidal Creek Seaward Seedling density ± SE density ± SE density ± SE density ± SE B2 D5 Change (D5 - B2) Control Impact Control Impact Control Impact Sapling density ± SE density ± SE density ± SE density ± SE B2 D5 Change (D5 - B2) Control Impact Control Impact Control Impact Prepared for INPEX Cardno Page 21

33 Figure 4-4 Mean (± SE) seedling density in the four assemblages from landward to seaward recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison with the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013) Prepared for INPEX Cardno Page 22

34 Figure 4-5 Mean (± SE) change in seedling density between B2 (July/August 2012) and D5 (October/November 2013) in the four assemblages from landward to seaward at Control and Impact sites Sapling Density Sapling densities in D5 (October/November 2013) were low at all sites and in all assemblages (Appendix C- 2), with spatial patterns generally similar to previous surveys (Cardno and EcoScience NT 2012, 2013a, 2013b, 2013c, 2013d). Overall, changes in sapling density among surveys were minimal (<1 m 2 ); therefore, data summaries by assemblage are not presented. Similar to seedling density, analyses of sapling density found significant differences between some Locations but these were dependent on Assemblage (main model Assemblage x Location interaction p <0.001; Appendix D-2 B). No other significant differences were found, including the key terms of interest involving Phase and Treatment (i.e. Phase x Treatment p = 0.29; Phase x Treatment x Assemblage p = 0.37, Appendix D-2 B). Post-hoc tests were not performed because no terms of interest were found to be significant Seedling and Sapling Richness During D5 (October/November 2013), 12 mangrove seedling species were recorded at the ten monitoring sites in the random quadrats. This was slightly higher than previous surveys, which ranged from 10 to 11 species (Cardno and EcoScience NT 2012, 2013a, 2013b, 2013c). Species recorded comprised: Aegialitis annulata, Aegiceras corniculatum, Avicennia marina, Bruguiera exaristata, Bruguiera parviflora, Camptostemon schultzii, Ceriops australis, Excoecaria ovalis, Rhizophora stylosa, Sonneratia alba, Scyphiphora hydrophylacea and Xylocarpus moluccensis. In general, relative to B2 (July/August 2012), seedling species richness recorded during D5 (October/November 2013) varied very little and was consistently low, ranging from -0.3 ± 0.0 SE at Hinterland Margin Impact sites to 0.2 ± 0.1 at Tidal Creek Control sites (Table 4-6). Similar to previous surveys, sapling species richness was consistently low across the intertidal area. Relative to B2, species richness generally remained unchanged for all assemblages (Table 4-6). Overall, no clear or consistent patterns were observed, and changes in mean species richness from B2 to D5 were again small (<1 species). Prepared for INPEX Cardno Page 23

35 Table 4-6 Total mean (± SE) seedling and sapling species richness per quadrat recorded during B2 (July/August 2012) and D5 (October/November 2013) for Control and Impact treatments, for the four mangrove assemblages Site Type Hinterland Margin Tidal Flat Tidal Creek Seaward Seedling richness ± SE richness ± SE richness ± SE richness ±SE B2 D5 Net change (D5-B2) Control Impact Control Impact Control Impact Sapling richness ± SE richness ± SE richness ± SE richness ±SE B2 D5 Net change (D5-B2) Control Impact Control Impact Control Impact Seedling Survival and Growth Seedling Survival In D5 (October/November 2013), the mean number of seedlings monitored in permanent quadrats was greatest in the Seaward assemblage, intermediate in the Tidal Flat and Tidal Creek assemblages, and least in the Hinterland Margin assemblage (Table 4-7). Lower mean values occurred at the Impact sites than at Control sites during D5, compared with B2 in which lower numbers occurred in Impact sites for only the Hinterland Margin assemblages. For individual sites, there was large variability in seedling numbers and survival rates, with high attrition rates at some assemblages and sites (Appendix C-3). Total seedling number and survival rate was lowest in the Hinterland Margin for Impact sites (38.3% ± 0.6 SE) (Table 4-7, Figure 4-6). Site I2 in particular had 0.0% survival since B2 (July/August 2012) (Appendix C-3). Despite having the most seedlings, the Seaward assemblage Impact sites also showed low average survival (51.5% ± 2.3 SE) (Table 4-7). Site I5 recorded less than 20% seedlings surviving since B2 (Appendix C-3). Survival was also low in the Tidal Flat assemblage at Control sites (54.3% ± 1.4 SE), largely driven by Site C2, which had survival of only 5% of seedlings since B2 (Appendix C-3). Although mean survivorship significantly differed among Sites (within Treatments) depending on Assemblage ( Location (Treatment) x Assemblage ) term, p <0.01), there were no significant differences detected between Control and Impact sites ( Treatment x Assemblage term, p = 0.11; Treatment term, p = 0.15) (Appendix D-3 L). The percentage of seedlings surviving has steadily declined in all sites and assemblages over time (Figure 4-7, Appendix C-3). The relatively lower survival rates in the Hinterland Margin and Seaward assemblages at Impact sites in D5 (October/November 2013) were largely due to poor survival between B2 (July/August 2012) and D1 (October/November 2012), with less that 70% survival in the Hinterland margin and less than 80% in the Seaward assemblage (Figure 4-7). Overall, since D1, survival has been similar for Control and Impact sites ( Treatment term, p = 0.15; Appendix D-3 L). Prepared for INPEX Cardno Page 24

36 Table 4-7 Mean (± SE) number of individual seedlings per quadrat for Control and Impact sites recorded during B2 (July/August 2012) and D5 (October/November 2013), and percentage survival from B2 to D5 Site Type Hinterland Margin Tidal Flat Tidal Creek Seaward Number ± SE Number ± SE Number ± SE Number ± SE B2 D5 Control Impact Control Impact % ± SE % ± SE % ± SE % ± SE % survival D5- B2 Control Impact Figure 4-6 Mean (± SE) percentage survival of individual seedlings from B2 (July/August 2012) to D5 (October/November 2013) in the four assemblages from landward to seaward recorded at Control and Impact sites Prepared for INPEX Cardno Page 25

37 Figure 4-7 Mean (± SE) percentage survival of individual seedlings in the four assemblages from landward to seaward recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison with the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013) Prepared for INPEX Cardno Page 26

38 Level 2 Trigger Assessment The net percentage change in seedling survival (pooled Impact pooled Control sites) was -8.0%, with mean percentage seedling survival greater for Control (64.6% ± 0.8 SE) than Impact sites (56.6% ± 0.7 SE) (Table 4-8). The trigger t-test for seedling survival from B2 to D5 found that the difference in mean survival at Control and Impact locations was non-significant (p = 0.08, Appendix D-3 M). The Level 2 trigger for seedling survival (>50% net change) was not exceeded during D5. Table 4-8 Summary of mean seedling survival since B2 (July/August 2012) at Control and Impact sites (data pooled for sites and assemblages), and survival calculated for Impact Control Control Sites (%) Impact Sites (%) Impact Sites Control Sites (%) Mean ± SE Mean ± SE Net survival Mean seedling survival (B2 D5) Relationship Between Seedling Survival and Intertidal Sedimentation There was no significant relationship between net sedimentation and percentage change in seedling survival in D5 (October/November 2013) for any of the four assemblages (p ranged between 0.05 and 0.75; Table 4-9). In the Tidal Creek assemblage there was a weak (but not significant, p = 0.05) trend toward increased seedling survival with increasing net sedimentation (Figure 4-8). Table 4-9 p-values from the F-tests for linear regression between net sedimentation and percentage change in seedling survival for each assemblage for D5 (October/November 2013) Assemblage p-value Tidal Creek 0.05 Tidal Flat 0.75 Hinterland Margin 0.72 Seaward 0.35 Prepared for INPEX Cardno Page 27

39 Figure 4-8 Net sedimentation (mm) versus percentage change in seedling survival at D5 (October/November 2013) for each assemblage. Each point represents the average for site within an assemblage. Impact sites are red and Control sites are blue Leaves and Leaf Change Consistent with results from previous surveys (D1, D2, D3 and D4), during D5 there were generally more leaves on surviving seedlings in all assemblages than in B2 (July/August 2012) and overall Control Sites had a greater number of leaves (Table 4-10, Figure 4-9, Figure 3-10). In the Hinterland Margin and Seaward assemblages, percentage change in leaf counts was similar between Control and Impact sites. In the Tidal Flat assemblage, leaf counts were considerably higher in Control than Impact sites; however, this was reversed in the Tidal Creek assemblage (Table 4-10). This variation differed to previous surveys, in which there was a greater increase in leaves at three assemblages in Control sites (Cardno and EcoScience NT 2012, 2013a, 2013b, 2013c, 2013d). The largest increase in number of leaves on seedlings from B2 (July/August 2012) to D5 (October/November 2013) was in the Tidal Creek assemblage at Impact sites (53.7% ± 6.6 SE); however, other assemblages showed similar percentage change (Table 4-10, Figure 4-10). Despite the Seaward assemblage having the largest number of seedlings (Table 4-7), this assemblage had the lowest number of leaves per plant and lowest percentage leaf change, with Control and Impact sites having similar percentage change (~22%) (Table 4-10, Figure 4-10). Sites I4 and I5, which both recorded low seedling survival rates, also showed declines in number of leaves (Appendix C-3). Prepared for INPEX Cardno Page 28

40 Table 4-10 Mean (± SE) leaf counts per individual seedling and mean percentage leaf change per permanent quadrat (± SE) by assemblage from Control and Impact sites during B2 (July/August 2012) and D5 (October/November 2013) Site type Hinterland Margin Tidal Flat Tidal Creek Seaward leaves ± SE leaves ± SE leaves ± SE leaves ± SE B2 D5 % change D5-B2 Control Impact Control Impact % ± SE % ± SE % ± SE % ± SE Control Impact The change in leaf count for all species combined (i.e. for all plants in each plot) from B2 to D5 was analysed using PERMANOVA and no differences were detected between Control and Impact Locations (Treatment p = 0.62; Treatment x Assemblage = 0.60, Appendix D-3 A). Some differences were noted between Locations and these were dependent on Assemblage (Location (Treatment) x Assemblage p < 0.05, Appendix D-3 A). No post-hoc tests were performed as this interaction was not considered of interest for monitoring dredging impact. The following mangrove species were analysed for change in leaf count (at the level of individuals plants): Aegiceras corniculatum (Seaward assemblage sub-dominant); Rhizophora stylosa (Tidal Creek assemblage dominant), Bruguiera parviflora (Tidal Creek assemblage sub-dominant) and Ceriops australis (recorded in Tidal Flat and Hinterland Margin assemblages). In all cases, there were no significant differences in the change in leaf counts between Control and Impact locations (i.e. Treatment or Treatment x Assemblage p >0.05); however, localised differences between locations within each treatment were recorded (i.e. Location factor was significant p < 0.05) (Appendix D-3 C to F). Prepared for INPEX Cardno Page 29

41 Figure 4-9 Mean (± SE) number of leaves per plant on individual seedlings in the four assemblages from landward to seaward recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison with the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013) Prepared for INPEX Cardno Page 30

42 Figure 4-10 Mean (± SE) percentage of change in the number of leaves of seedlings between B2 (July/August 2012) and D5 (October/November 2013) in the four assemblages from landward to seaward at Control and Impact sites Level 2 Trigger Assessment The Level 2 trigger for seedling growth (>50% net change) was not exceeded during D5 (October/November 2013). Seedling growth, measured by net percentage change in mean leaf counts for individual seedlings from B2 (July/August 2012) to D5 (October/November 2013) (pooled mean for Impact sites pooled mean for Control sites) was 1.1%, which was not statistically significant (p = 0.79) (Appendix D-3 B). Mean percentage change in leaves on individual seedlings was similar between Control sites (31.6% ± 2.9 SE) and Impact sites (32.7% ± 2.7 SE) when data were pooled for sites and assemblages (Table 4-11, Appendix C- 1 B). Table 4-11 Mean (±SE) percentage change in seedling leaf numbers between B2 (July/August 2012) and D5 (October/November 2013), expressed as % of B2 at Control and Impact sites (data pooled for sites and assemblages). Net percentage change calculated for Impact Control Control Sites (%) Impact Sites (%) Impact Sites Control Sites (%) Mean ± SE Mean ± SE Net change Mean change in number of leaves (D5 - B2) Relationship between Change in Number of Leaves and Intertidal Sedimentation In D5 (October/November 2013), there was no significant relationship between net sedimentation and percentage change in in seedling leaf number (growth) for any of the four assemblages (Figure 4-11); p- value ranged between 0.07 and 0.96 (Table 4-12). At most sites, leaf change was generally positive with no noticeable relationship between seedling leaf change and recorded sedimentation (Figure 4-11). The Tidal Flat assemblage showed a weak but not significant potential trend of increasing sedimentation and decline in new leaf production. Impact Site I3 had the highest net sedimentation in the Seaward assemblage (Z8), and canopy cover reduction (Section 4.1.1, Figure 4-3) and overall seedling density was very low (Appendix C-2). Although seedling survival in D5 was over 75% for this assemblage/site (Appendix C3), change in number of leaves was low (Figure 4-11), as was the number of leaves per plant (Appendix C-3). Prepared for INPEX Cardno Page 31

43 Figure 4-11 Net sedimentation (mm) versus change in number of leaves (% per plant) during D5 (October/November 2013) for each assemblage. Each point represents the average for site within an assemblage. Impact sites are red and Control sites are blue Table 4-12 The p-values from the F-tests for linear regression between net sedimentation and change in number of leaves (%/plant) for each assemblage for D5 (October/November 2013) Assemblage p-value Tidal Creek 0.17 Tidal Flat 0.07 Hinterland Margin 0.96 Seaward Nodes and Nodal Change Patterns in seedling node counts and nodal change from B2 (July/August 2012) through D5 (October/November 2013) generally indicated that gradual vertical growth of Rhizophoraceae seedlings has been occurring in the Hinterland Margin, Tidal Flat and Tidal Creek assemblages at both Control and Impact sites (Table 4-13, Figure 4-12, Appendix B-3). Nodal data were not obtained for seedlings in the Seaward assemblage due to the absence of suitable species (i.e. Rhizophoraceae seedlings). In D5, mean node counts were again highest in the Tidal Creek assemblage for Control sites (10.3 ± 1.1 SE) and for Impact sites (6.8 ± 0.2 SE), with percentage nodal change from B2 also greatest in that assemblage (156.9% ± 30.3 SE and 156.2% ± 7.0 SE for Control and Impact sites, respectively) (Table 4-13, Figure 4-12, Figure 4-13). There was considerable variability between sites for both Impact and Control sites, particularly in the Hinterland Margin and Tidal Creek assemblages (Appendix C-3). Prepared for INPEX Cardno Page 32

44 For all species combined from B2 to D5, no differences were detected between Control and Impact locations (Treatment p = 0.67; Treatment x Assemblage = 0.75, Appendix D-3 G). Some differences were noted between Assemblages (Assemblage factor significant p < 0.01, Appendix D-3 G). However, no post-hoc tests were performed as this interaction was not considered of interest for monitoring dredging impact. Table 4-13 Mean (±SE) number of nodes per seedling and percentage change in nodes between B2 (July/August 2012) and D5 (October/November 2013), expressed as % of B2 at Control and Impact sites (data pooled for sites and assemblages). Net percentage change calculated for Impact Control Site Type Hinterland Margin Tidal Flat Tidal Creek nodes ±SE nodes ±SE nodes ±SE B2 D5 Control Impact Control Impact % ± SE % ± SE % ± SE % change (D5 B2) Control Impact Note: No Seaward assemblage data available as there were no suitable species present (i.e. Rhizophoraceae) Prepared for INPEX Cardno Page 33

45 Figure 4-12 Mean (± SE) number of nodes per individual Rhizophoraceae seedling in the Hinterland Margin, Tidal Flat and Tidal Creek assemblages recorded at Control and Impact sites during the Dredging Phase (D1 to D5), in comparison to the Baseline Phase (B2). B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013), D4 (July 2013) and D5 (October/November 2013). No Seaward assemblage data available as there were no suitable species present (i.e. Rhizophoraceae) Prepared for INPEX Cardno Page 34

46 Figure 4-13 Mean (±SE) percentage change in the number of nodes per individual Rhizophoraceae seedling from B2 (July/August 2012) to D5 (October/November 2013) in three of the four assemblages from landward to seaward at Control and Impact sites. No Seaward assemblage data available as there were no suitable species present (i.e. Rhizophoraceae) Level 2 Trigger Assessment The net percentage change in mean node counts for individual seedlings from B2 (July/August 2012) to D5 (October/November 2013) (pooled Impact pooled Control sites) found there were no significant differences in the change in node counts between Control and Impact locations (i.e. Treatment or Treatment x Assemblage p >0.05; Appendix D-3 I to K). The Level 2 trigger for seedling growth (>50% net change) based on node counts was not exceeded during D5 (October/November 2013) (Table 4-14). Table 4-14 Mean (± SE) percentage change in number of nodes on seedlings at Control and Impact sites (data pooled for sites and assemblages) and net percentage change calculated for Impact Control Control Sites (%) Impact Sites (%) Impact Sites Control Sites (%) Mean ± SE Mean ± SE Net change Mean change in number of nodes (D5 - B2) Relationship between Change Number of Nodes and Intertidal Sedimentation Between B2 (July/August 2012) and D5 (October/November 2013), there was no significant relationship between net sedimentation and percentage change in number of nodes for any of the three assemblages (Figure 4-14, p-value ranged between 0.14 and 0.77; Table 4-15). Prepared for INPEX Cardno Page 35

47 Figure 4-14 Net sedimentation (mm) versus percentage change in number of nodes (per cent per plant) at D5 (October/November 2013) for each assemblage. Each point represents a site, which is labelled to the left or above. Impact sites are red and Control sites are blue Table 4-15 The p-values from the F-tests for linear regression between net sedimentation and change in number of nodes for each assemblage for D5 (October/November 2013) Photo-monitoring Assemblage p-value Tidal Creek 0.14 Tidal Flat 0.77 Hinterland Margin 0.66 Photo-monitoring images for B1 (June 2012) and D5 (October/November 2013) are presented in Appendix E. Images for Impact sites are presented in Appendix E-1 and Control sites in Appendix E-2. Four images are provided from each plot with the date, site, assemblage and direction (i.e. photographer facing toward either corner post 1, 2, 3 or 4) indicated on the plot identification board (when not obscured by vegetation). It is evident from photo-monitoring images that some minor changes in forest structure and physiognomy have occurred during the 16-month period since B1. The most noticeable changes are the shedding of branches and attrition of small dead trees. These minor changes were typically observed at both Control and Impact sites. As noted in D4 (July 2013; Cardno and EcoScience NT 2013d), the most pronounced visual changes evident from photo-monitoring during D5 (and also evident in images from previous surveys) were observed in the Seaward assemblage at Impact Site I2, where the density of small Aegiceras corniculatum trees has declined since B1, (Appendix E-1, Site I28-1), apparently by natural senescence. Despite this site/assemblage recording a small amount of net sedimentation since the Baseline Phase (5.0 mm) (Cardno Prepared for INPEX Cardno Page 36

48 2013b), field observations have noted microscale patchiness across the site with some evidence of localised erosion, which may have removed the low trees. However, these A. corniculatum trees may have been over-mature when photographed during B1 and so the observed changes may be due only to natural senescence. Moreover, relatively substantial seedling and sapling mortality was also recorded in the Seaward assemblage at Impact sites (Section 4.1.3). 4.2 Fauna Results General Findings Total species richness (248 species) recorded during D5 (October November 2013) (Table 4-16 and Appendix F-2, Table F-2 B-H) was similar to that recorded in D2 (January/February 2013) and D3 (April/May 2013) (both 249) but less than the pooled total for B1/B2 (271 species) (Table 3-16). Fauna was not surveyed during D4 (July 2013). Based on all six surveys undertaken to date, species richness of fauna was dominated by molluscs (27%), crustaceans (26% of total, comprising 14% decapod crabs and 12% other crustaceans), and worm species (26%), collectively comprising 79% of all species (Table 4-16). Seventy mollusc species were recorded during D5, along with 55 worm, 42 crab, 33 other crustacean, 24 ant, 20 fish and 4 other invertebrate fauna species. A complete (cumulative) list of all species recorded to date is provided in Appendix F-2, Tables F-2 B to F-2 H, indicating the Family, taxonomic group and presence of each species at Control and Impact sites. Total abundance during D5 (8,402 records; October/November 2013) (Table 4-16 and Appendix F-2, Table F-2 B-H) was similar to that during D3 (8,501 records; April/ May 2013) and greater than in D1 (7,170; October/November 2012) but was less than the pooled total for B1/B2 (8,970; June August 2012). The combined total number of individuals recorded from all surveys to date (B1, B2, D1, D2 and D3) is 41,606 from 393 species (Table 4-16). In terms of the total number of records (frequency), the fauna was dominated by crustaceans (53%, comprising 41% decapod crabs and 12% other crustaceans), molluscs (26%) and worms (13%), collectively comprising 92% of all records. Similar to previous surveys, there were more fauna recorded in D5 in the Impact treatment (4,971 individuals) than for the Control treatment (3,431 individuals), primarily because six Impact sites were sampled in comparison with four Control sites New Taxonomic Records Nine new taxonomic records for Darwin Harbour mangrove habitats were obtained during D5 (Table 4-17) comprising four crustaceans, three molluscs, one worm and one fish. To date, faunal surveys for this monitoring project have produced 68 new taxonomic records for mangrove habitats in Darwin Harbour comprising 18 worms, 17 molluscs, 16 crustaceans, 11 ants, four fish and two other fauna species. Appendix F-2 A contains a summary table listing the 68 new taxonomic records, indicating the family, taxonomic group and the survey during which it was recorded. The summary table also highlights those species that represent new records for Darwin Harbour and new species for the Northern Territory Species Richness A summary table of the mean total fauna species richness recorded at Control and Impact sites within each of the four main assemblages is presented in Table The values represent mean species richness (all taxa) for B1, B2, D1, D2, D3 and D5 calculated from three replicate sampling stations per monitoring plot, averaged across Control and Impact sites. A more detailed summary of mean total fauna species richness from assemblages at each site, averaged for B1/B2 (pooled) and D5 is compiled in Appendix F-1 A. Prepared for INPEX Cardno Page 37

49 Table 4-16 Total number of fauna species and individuals (in parentheses) for each taxonomic group recorded during B1, B2, D1, D2, D3 and D5. B1 and B2 (pooled) for the four mangrove assemblages at Control and Impact sites. The overall species richness and percentage of records for all surveys to date are also indicated. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013). * Abundance was not recorded for ants Survey B1 and B2 pooled D1 D2 D3 D5 Overall spp. richness (% total sp. rich.) Percentage of all species records (all surveys) Ants* Decapod Crabs Other Crustaceans Taxonomic Group Molluscs Worms Other Inverts. Fish Total sp. Richness Total Individuals Control (1,243) 26 (412) 56 (990) 34 (567) 5 (15) 13 (143) 197 3,546 Impact (2,358) 29 (481) 72 (1,409) 47 (734) 6 (26) 16 (173) 241 5,424 Overall (3601) 33 (893) 79 (2399) 58 (1301) 8 (41) 19 (316) Control (1,320) 25 (418) 47 (758) 29 (284) 3 (3) 12 (139) 183 3,040 Impact (1,995) 23 (506) 56 (778) 34 (526) 5 (16) 12 (145) 195 4,130 Overall (3,315) 33 (924) 62 (1,536) 46 (810) 5 (19) 16 (284) 235 7,170 Control (1,237) 20 (690) 49 (1,147) 32 (371) 4 (12) 15 (109) 180 3,689 Impact (1,828) 29 (966) 57 (1,172) 43 (574) 7 (24) 16 (157) 212 4,873 Overall (3,065) 30 (1,656) 68 (2,319) 50 (945) 8 (36) 20 (266) 249 8,562 Control (1,095) 22 (459) 54 (865) 29 (414) 4 (14) 17 (162) 182 3,115 Impact (2,135) 22 (374) 67 (1,828) 45 (653) 4 (19) 15 (237) 214 5,386 Overall (3,230) 29 (833) 75 (2,693) 52 (1,067) 7 (33) 18 (399) 249 8,501 Control (1,247) 23 (352) 53 (843) 41 (517) 2 (9) 18 (343) 197 3,431 Impact (2,397) 29 (449) 62 (943) 44 (859) 3 (29) 17 (156) 215 4,971 Overall (3,644) 33 (801) 70 (1,788) 55 (1,377) 4 (38) 20 (499) 248 8, (11%) 55 (14%) 50 (12%) 106 (27%) 100 (26%) 12 (3%) 28 (7%) ,606 4% 41% 12% 26% 13% 0.4% 4% Prepared for INPEX Cardno Page 38

50 Table 4-17 New taxonomic records for species sampled during D5 (October/November 2013) Species Name Family Taxonomic Group Notes Diplodonta sp. 1 Ungulinidae bivalve New DH mangrove record Blenniidae sp. 1 Blenniidae fish New DH mangrove record Leucotina sp. 2 Ebalidae gastropod New DH mangrove record Pseudoliotia sp. 2 Tornidae gastropod New DH mangrove record Oniscidae sp.4 Oniscidae isopod New DH mangrove record Cumacea sp. Cumacea^ shrimp New DH mangrove record Mysidacea sp. Mysidacea^ shrimp New DH mangrove record Penaeidae sp. Penaeidae shrimp New DH mangrove record Amaena sp. 1 Terebellidae worm New DH mangrove record ^ Order Table 4-18 Mean (± SE) total fauna species richness per sampling station for B1, B2, D1, D2, D3 and D5 for Control and Impact sites in the four mangrove assemblages. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) Survey Type Hinterland Margin Tidal Flat Tidal Creek Seaward mean ±SE mean ±SE mean ±SE mean ±SE B1 B2 D1 D2 D3 D5 Control Impact Total Control Impact Total Control Impact Total Control Impact Total Control Impact Total Control Impact Total Prepared for INPEX Cardno Page 39

51 Mean total faunal species richness during D5 (October/November 2013) was slightly higher than mean richness during the previous fauna survey (D3; April/May 2013) (Table 4-16, Figure 4-15). This pattern was observed at Control and Impact sites, and across all assemblages except the Hinterland Margin. For the Hinterland Margin assemblage the estimates of richness for both Control (10.1 ± 1.0 SE) and Impact (9.7 ± 0.7 SE) sites during D5 was similar to both Control (11.2 ± 1.0 SE) and Impact (9.3 ± 0.8 SE) sites during D1 (October/November 2012), which was undertaken 12 months prior (Figure 4-15). Total spp. richness (+/-SE) Treatment Control Impact 5 0 Survey Assemblage B1 B2 D1 D2 D3 D5 Hinterland Margin B1 B2 D1 D2 D3 Tidal Flat D5 B1 B2 D1 D2 D3 Tidal Creek D5 B1 B2 D1 D2 D3 Seaward D5 Figure 4-15 Mean (± SE) total fauna species richness in the four assemblages from landward to seaward recorded during B1, B2, D1, D2, D3 and D5. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) Similar to results for all previous surveys, total fauna species richness differed amongst the four mangrove assemblages, with richness increasing from landward to seaward during D5 (Table 4-18, Figure 4-15). Mean total fauna richness was highest in the Seaward assemblage (32.3 ± 1.2 SE), intermediate in the Tidal Creek (25.5 ± 1.1 SE) and Tidal Flat (21.6 ± 1.0 SE) assemblages, and least in the Hinterland Margin (9.8 ± 0.6 SE). The minimum mean species richness per sampling station during D5 was recorded in the Hinterland Margin at Site I5 (7.0 ± 1.7 SE) and the maximum (35.7 ± 4.3 SE) was recorded in the Seaward assemblage at Site C2 (Appendix F-1 A). Appendix F-3 presents graphs of mean fauna species richness values for each of the main taxonomic groups (ants, crabs, other crustaceans, molluscs, worms and other invertebrate fauna species) for all surveys at Control and Impact sites within the four assemblages. Mean species richness was significantly different between Baseline and Dredging Phases (p <0.01) depending on the Assemblage and Location (Appendix G-1 A). Post-hoc tests revealed that these differences occurred in both Control and Impact Locations, and in all Assemblages (Appendix G-1 B). The general trend was that where significant differences occurred, species richness was higher during Dredging surveys than Baseline surveys. Species richness also varied between some Surveys and this was dependent on Assemblage (p <0.05) (Appendix G-1 A, Appendix G-1C). Post-hoc pairwise t-tests were Prepared for INPEX Cardno Page 40

52 not performed on this interaction as temporal differences (i.e. Survey) not dependent on Treatment were not of interest to the monitoring program objectives Abundance A summary of results for total fauna abundance recorded at Control and Impact sites within each of the four assemblages is presented in Table The values represent mean abundance (all species) for all surveys calculated from three replicate sampling stations per monitoring plot, averaged across Control and Impact sites. A more detailed summary of means for total fauna abundance from assemblages at each site, averaged for B1/B2 (pooled) and D5 is compiled in Appendix F-1 B. Table 4-19 Mean total fauna abundance (± SE) per sampling station for B1, B2, D1, D2, D3 and D5 for Control and Impact sites in the four mangrove assemblages. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) Survey Type Hinterland Margin Tidal Flat Tidal Creek Seaward mean ± SE mean ± SE mean ± SE Mean ± SE B1 B2 D1 D2 D3 D5 Control Impact Total Control Impact Total Control Impact Total Control Impact Total Control Impact Total Control Impact Total In D5 (October/November 2013), total fauna abundance in the Tidal Creek and Seaward assemblages (pooled Impact and Control sites) was higher than all previous surveys, including D1, which also took place at the end of the dry season (October/November 2012) (Table 4-19, Figure 4-16). Total fauna abundance in the Hinterland Margin assemblage was lower in D5 than for all surveys except for B1 and B2. In the Tidal Flat assemblage, abundance was greater than D1 but less than D2 (January/February 2013) and D3. As was also found for previous surveys, abundance in D5 (October/November 2013) was consistently higher than for B1/B2, which was carried out in the middle of the dry season (June and July/August 2012), indicating seasonal and inter-annual variability. In contrast to all previous surveys, during D5 total fauna abundance (sites pooled) in the Tidal Creek (75.2 ± 4.9 SE) was higher than the Tidal Flat (67.8 ± 4.1 SE) assemblage. Prepared for INPEX Cardno Page 41

53 The lowest mean abundance was recorded in the Hinterland Margin assemblage (26.1 ± 7.1 SE). In D5, abundance was greater in the Impact sites than in the Control sites in the Tidal Creek and Seaward assemblages, but the converse was found in the Tidal Flat and Hinterland Margin assemblages (Table 4-19, Figure 4-16). The minimum mean abundance per sampling station during D5 was recorded in the Hinterland Margin at Site C2 (7.0 ± 2.5 SE) and the maximum (160.0 ± 30.4 SE) was recorded in the Seaward assemblage at Site I1 (Appendix F-1 B). Total abundance (+/-SE) Treatment Control Impact 20 0 Survey Assemblage B1 B2 D1 D2 D3 D5 Hinterland Margin B1 B2 D1 D2 D3 Tidal Flat D5 B1 B2 D1 D2 D3 Tidal Creek D5 B1 B2 D1 D2 D3 Seaward D5 Figure 4-16 Mean total fauna abundance (±SE) in the four main assemblages from landward to seaward recorded during B1, B2, D1, D2, D3 and D5. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) Species abundance was significantly different between Phases in some Assemblages depending on Treatment (p <0.01) (Appendix G-1 D). Abundances recorded during Dredging surveys were significantly higher than abundances during the Baseline surveys, for Control sites in the Tidal Flat and Tidal Creek, and for Impact sites in the Hinterland Margin and Seaward assemblages (Appendix G-1 E, F). However, posthoc tests did not detect any significant difference between Control and Impact sites, in any assemblage or either Phase (p >0.05 in all cases; Appendix G-1 E). Smaller scale spatial and temporal differences in abundance were also detected with abundance varying between Locations and Surveys, but both were dependent on Assemblage (p <0.001 for Survey x Assemblage; and p <0.05 for Location x Assemblage, Appendix G-1 D). Plots of mean fauna abundance for each of the taxonomic groups (ants, crabs, other crustaceans, molluscs, worms and other fauna) for all surveys for Control and Impact sites within the four assemblages are presented in Appendix F Fauna Community Composition Ordinations based on the presence/absence of all fauna species within monitoring plots in the four assemblages showed little distinction between Control and Impact sites (Figure 4-17). This is indicated on the ordination by the scattered distribution of all points, with no clear clustering of either Control or Impact sites. Similarly, there was little visual evidence of distinction between any of the surveys undertaken since Prepared for INPEX Cardno Page 42

54 B1 (June 2012) (Figure 4-17). However, analyses revealed significant differences in species composition between Phases, but these were dependent on Assemblage (i.e. Phase x Assemblage and Phase x Location significant p <0.01, Appendix G-1 G). Post-hoc tests showed that these temporal differences occurred within all assemblages and at both Control and Impact Locations (Appendix G-1 H). Differences in community composition between Surveys and Assemblage for some Locations were also detected (p <0.05) (Appendix G-1 G). In general, compositional change between Phases was in accordance with the observed increases in species richness and abundance from the Baseline to Dredging Phases, and the changes from dry season to wet season, described in Sections and Invertebrate presence/absence indicating survey and treatment 2D Stress: 0.19 Survey-Treatment B1-Control B1-Impact B2-Control B2-Impact D1-Control D1-Impact D2-Control D2-Impact D3-Control D3-Impact D5-Control D5-Impact Figure 4-17 Ordination of sampling stations at Control (grey) and Impact (blue) sites during B1 (upward triangles), B2 (downward triangles), D1 (open circles), D2 (closed circles), D3 (open squares) and D5 (closed squares) based on presence/absence of fauna species. Data were pooled for all sampling methods per station in each of the four assemblages B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) The clear distinction between faunal abundance in different assemblages observed during previous surveys was still evident with the inclusion of D5 data (Figure 4-18), with points representing sites in different assemblages clearly grouped into separate sections of the ordination. This trend was also characteristic of patterns recorded in previous mangrove surveys in Darwin Harbour (EcoScience NT 2012; Metcalfe 2007, 2010). When the same ordination was re-displayed to examine season (Figure 4-19) no clear distinction between mean fauna abundance during wet and dry season sampling was evident. Although season is not a factor in the current experimental design, temporal change is examined by the Survey factor, already noted as having some effects on species composition, dependent on Assemblage and Location (Appendix G-1 H). Community composition was also examined for the three main taxonomic groups: crustaceans, molluscs and worms, and similar trends were noted in these nmds ordinations (Appendix G-1 I, J and K). There was little evidence of distinction between Treatments, or in relation to Baseline versus Dredging, and therefore no clear indication of impact from dredging activities. Prepared for INPEX Cardno Page 43

55 Invertebrate presence/absence indicating assemblage 2D Stress: 0.19 Assemblage Hinterland Margin Tidal Flat Tidal Creek Seaward Figure 4-18 Ordination of sampling stations sampled during B1, B2, D1, D2, D3 and D5 in the four assemblages based on the presence/absence of fauna species. Data were pooled for all sampling methods used per station. B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) Invertebrate presence/absence indicating season 2D Stress: 0.19 Season dry wet Figure 4-19 Ordination of sampling stations sampled during dry (green) and wet (blue) season based on the presence/absence of fauna species. Data were pooled for each sampling method for dry and wet season surveys (B1, B2, D1, D2, D3 and D5). B1 (June 2012), B2 (July/August 2012), D1 (October/November 2012), D2 (January/February 2013), D3 (April/May 2013) and D5 (October/November 2013). No data were obtained for D4 (July 2013) Prepared for INPEX Cardno Page 44

56 5 Discussion 5.1 Mangrove Community Health Flora A possible impact pathway to mangroves was identified in the Ichthys Gas Field Development Project Draft Environmental Impact Statement (INPEX 2011) whereby dredging was predicted to result in increased sedimentation in intertidal areas of mangrove forests and indirectly impact mangrove health by smothering and burial of root systems. Impacts could range from reduced vigour to death, depending on the amount and type of sedimentation, the rate and depth of burial and the mangrove species involved. As mangroves may exhibit slow response rates to non-acute stresses such as cumulative sedimentation (i.e. there may be a delay of up to a year before trees show signs of impact (Norm Duke (2012), pers. comm.), any temporal trends to canopy cover, seedling survivorship and growth need to be closely monitored. Dredging for Season One of the East Arm dredging component of the Project was completed on 30 April 2013, and Season Two Project dredging commenced on 23 October 2013 with the GEP, therefore a maximum of 19 days of dredging occurred in the three months prior to the completion of D5 MCH data collection on 11 November There was a slight reduction in canopy cover from B2 (July/August 2012) to D5 (October/November 2013) at Control (-1.1 ± 0.4 SE) and Impact sites (-2.1% ± 0.4 SE) for all assemblages. This was mostly driven by reduced cover in the Seaward assemblage at sites I2, I3 and I5 (-9.9%, -10.3% and -8.1% respectively). However, this reduction (at Impact sites) was well below the trigger level of 30%, and has been evident since D1 (October/November 2012). Similar to all previous dredging surveys (D1 to D4), canopy cover during the Dredging Phase (surveys pooled) was significantly less than during the Baseline Phase at Impact sites but not at Control sites. Although the change (at Impact sites) has been small, overall canopy cover is less than for the cover in the Baseline Phase. Despite the significance of this result, as discussed previously (Cardno and EcoScience NT 2013a, 2013c), changes in canopy cover of this nature are likely to be natural, or relate to the inherently high variability associated with measurement of canopy cover in some sites for some assemblages. Monitoring of seedling survival and growth indicated that net change from B2 to D5 in these indicators were well below Level 2 trigger levels (>50% net change in seedling growth and survivorship), with net seedling growth (pooled Impact minus pooled Control site data) at D5 of -1.1% based on leaf counts and -3.8% based on node counts, and net seedling survival of -8.0%. However, for individual sites (Control and Impact) in some assemblages there was less than 50% survival at some assemblages/sites. Patterns in growth (measured by change in number of leaves and nodes) were similar to previous surveys (D1 to D4) and no significant difference between Control and Impact sites in mean leaf or node change (from B2 to D5) was detected. Similarly, analyses of individual species found no significant differences in leaf growth since B2 between Control and Impact sites. As was the case for the previous surveys, there were significant differences in leaf change from B2 to D5 among some of the ten sites monitored. Interpretation of spatial and temporal trends in differences among the sites indicates that naturally occurring variability was responsible for differences, rather than any effects from dredging (see discussion below regarding factors affecting seedling growth and survival). In general, little or no change in community structure, composition, regeneration or overall mangrove health was evident from comparison of D5 and B1 (June 2012) images taken at the six Impact monitoring sites. Images taken at the four Control sites verify a similar absence of spatial and temporal trends in mangrove community structure and composition elsewhere in Darwin Harbour. The absence of any discernible changes in physiognomy, regeneration, species composition or health at Impact sites suggests no discernible effects from dredging activities. Ellison (1998) noted that there are insufficient data available to establish specific tolerances for individual species but review of the available data concluded that sedimentation levels of up to 50 mm would be generally tolerable by mangrove communities throughout Darwin Harbour, regardless of the species affected (INPEX 2011). The Intertidal Sedimentation Monitoring Program (ISMP) has shown a general pattern of sediment accretion between B2 (July/August 2012) to D5 (October/November 2013) for most assemblages (Cardno 2013b), with a period of erosion between D2 and D3 (most apparent at Control sites rather than at Prepared for INPEX Cardno Page 45

57 Impact sites). At D5, net sedimentation based on array stakes was greatest in the Seaward assemblage for both Control and Impact sites (pooled values of 12.1 mm ± 1.2 SE and 16.4 mm ± 1.4 SE, respectively). The greatest net sedimentation in this assemblage was at Site I3 (27.4 mm ± 1.8 SE). For all other assemblages, average net sedimentation and predicted annual net sedimentation rates measured in D5 using array stakes were less than 10 mm at Impact and Control sites, which is considerably less than sedimentation levels that may impact mangrove health (50 mm) and are likely to be part of the natural cycle of accretion and erosion (Cardno 2013b). There was no significant relationship between net sedimentation and canopy cover or net sedimentation and percentage change in number of leaves or nodes for any of the assemblages. There was a weakly significant (P<0.05) positive relationship between intertidal sedimentation and seedling survival for the Tidal Creek assemblage (Figure 4-8). This suggests that seedling growth and survival during the Dredging Phase to date have not been negatively influenced by current levels of net sedimentation. This is not unexpected given that the levels of sedimentation recorded at Impact sites (16.4 mm ± 1.4 SE) were well below the level of net sedimentation that may start to impact on mangrove seedling health (50 mm). The available information on the tolerances of mangrove seedlings to sedimentation is limited. However, an increase in sensitivity to burial over 160 mm has been observed in Avicennia seedlings (Thampanya et al. 2002), corresponding with the results reported by Ellison (1998) suggesting that burial beyond 100 mm can cause some mortality. Sensitivity to burial varies substantially among species, with the Seaward species Sonneratia caseolaris being the most tolerant of abrupt, high sedimentation, with seedlings showing relatively high survival rates (greater than 50%) despite burial under 240 mm of sediment (Thampanya 2006). Overall however, the literature suggests that sedimentation to 50 mm (Level 1 and 2 sedimentation trigger) is not likely to have a significant impact leading to substantive seedling mortality. The low rates of seedling survival recorded at some assemblages/ sites are likely to be due to a range of physical and biological factors operating over different spatial and temporal scales. Predation, competition, the frequency and duration of tidal inundation, salinity and the availability of light are primary factors influencing the survival of mangrove seedlings (Krauss et al. 2008), and mortality is naturally high during the first year after establishment (Smith 1987). Studies have demonstrated that recruitment in mangroves, like other closed canopy forests, is largely controlled by gaps in the canopy, which affect the amount of light reaching the forest floor (Duke 2001; Clark 2004). Overall, the rate of seedling establishment is low compared to the high number of propagules borne by most species, most of which fail to reach optimum habitat (Saenger 2002). This is further evidenced by the recorded seedling species composition (particularly in the Seaward assemblage), which is often not representative of the typical saplings or mature tree species present, and therefore failure of seedlings is a natural process in the maintenance of the zonation pattern of mangroves in Darwin Harbour. Mangrove community health monitoring has now been carried out for over fifteen months (since Baseline) and D5 was conducted during the same season as D1 (October/November) in 2013 and 2012, respectively. Although the wet season officially commences at the start of November, quarterly surveys D1 and D5 began in October at the end of a long dry period. The remote sensing program has demonstrated clear seasonal patterns in mangrove condition (Cardno 2013d, 2013e) and seasonal variation was also evident in the fauna and to some extent in the field-based flora results. Remote sensing techniques detected a widespread decrease in mangrove condition in D1 (Cardno 2013d), which was greatest on the eastern side of East Arm where most of the Impact sites are located (see Figure 2-1). Declines in canopy cover and seedling density; and low rates of seedling survival were also recorded for this period, particularly in the Seaward assemblage. In general however, seedling survival for individually monitored seedlings did not show any clear spatial or seasonal trends, and overall there was a steady decline in number of seedlings since B2 for all assemblages, with the exception of a larger decline at Impact sites between B2 and D1 in the Seaward assemblage. The poor survival between B2 (July/August 2012) and D1 is unlikely to be related to dredging (which had only just commenced and less than 1.0 mm sedimentation had been measured across all sites), and is more likely to be due to seasonal factors. Diminished seedling survival during surveys during the late dry season is most likely due to the relatively harsh conditions, including high temperatures and salinity stress (McKee 1995) associated with little or no rainfall. Prepared for INPEX Cardno Page 46

58 Seasonal patterns in canopy cover appear to vary between assemblages, with the highest canopy cover occurring in Hinterland Margin and Seaward assemblages at D3 (April / May 2013) and in the Tidal Flat in D4 during July 2013 (Figure 4-1). Seasonal variability in canopy cover was least in the evergreen, monospecific Rhizophora stylosa forests of the Tidal Creek assemblage. While small changes in estimates of canopy cover at individual sites over time may simply be a consequence of measurement error, trends in canopy cover have been recorded at sites in some assemblages (Appendix C), which may indicate natural patterns rather than inherent variability in measurements. For instance, in the Tidal Flat assemblage at Site I5, canopy cover has declined slightly but consistently since B2. At Site I3, canopy cover had steadily decreased between D1 and D4 in the Seaward assemblage, however there was a slight increase during D5. Canopy cover varies with a number of environmental factors and may vary seasonally with rainfall, pore-water salinity, storm damage and associated phenological factors such as flowering, leaf production and leaf loss. The minor differences recorded in canopy cover recorded during dredging surveys to date are extremely small (e.g. <-2.1% ± 0.4 SE during D5) and appear to represent minor natural spatial variability in canopy cover within assemblages. Ecologically significant trends in canopy cover would be represented by much greater changes that exceed those associated with the inherently patchy canopy cover in several assemblages. The decision to set a trigger level of 30% for changes in canopy cover was based on expert assessment of the scale of change that was likely to reflect ecologically significant impacts to mangrove community health (INPEX 2012). Seedling density results suggest varying seasonal patterns for each assemblage. In the Hinterland Margin and Seaward assemblages seedling density was greatest in D4 (July 2013) similar to the pattern observed in B2 (July 2012), whereas the Tidal Flat and Tidal Creek assemblages generally had the highest numbers of seedlings during D3 (April May 2013) (Figure 4-4). This may reflect the differing seedling species composition in each assemblage and sampling immediately after the period of maximum recruitment, during the wet season months of November to April. As discussed previously, gaps in the forest canopy also represent a key factor influencing natural variation in seedling and sapling density that may influence sampling results independent of season and potential impacts of dredging. In summary, as found in previous surveys (D1 to D4), although some localised differences in seedling growth and survival were evident among sites and assemblages, changes are considered to reflect naturally occurring variation among sites. Similarly, changes in other key indicators, canopy cover and seedling and sapling density, were associated with natural spatial and temporal cycles as also observed during D1. Therefore, based on the absence of any impact pathway evident from the intertidal sedimentation results (Cardno 2013c) and no significant relationships between mangrove health indicators and net sedimentation or clear distinction between Control and Impact sites, no evidence of impacts from dredging were apparent on mangrove flora at monitoring sites during D5 (October/November 2013). 5.2 Mangrove Community Health Fauna Fauna associated with marine and mangrove ecosystems are also likely to be impacted by a change in environmental conditions and can act as early warning indicators of environmental impacts (Bilyard 1987; Grall and Glemarec 1997; Moverley 2000), such as an increase in sedimentation. The 247 species recorded during D5 was slightly lower than the numbers recorded for D3, D2 (both 249 species) but greater than the D1 (235) survey. Consistent with previous results total species richness in D5 was less than the 271 species recorded during the B1 and B2 surveys combined. Indeed, the latter reflects the increased sampling effort involved in conducting two surveys (40 field days) compared with D5 alone (20 field days). During D5 (October/November 2013) species richness was similar or slightly higher per plot, than D1, D2 and D3, with the exception of the Hinterland Margin assemblage, where mean species richness was lowest for any of the Dredging surveys. Despite species richness being low in the Hinterland Margin assemblage in both Control (10.1 ± 1.0 SE) and Impact (9.7 ± 0.7 SE) sites in D5, richness was similar to that recorded in the same treatments (Control 11.2 ± 1.0 SE; Impact 9.3 ± 0.8 SE) during the D1 (October/November 2012) late dry, early wet season survey. The late dry season to early wet season follows a period of reduced frequency and amplitude in tidal inundation, and is also the period of maximum salinity and aridity, which contributes to diminished richness and abundance of mangrove fauna in this assemblage (Metcalfe 2007). Prepared for INPEX Cardno Page 47

59 As with previous surveys, data for species richness demonstrated close consistency between Control and Impact sites for faunal surveys during D5. Pooled mean species richness for Control sites (19.1 ± 0.5 SE) and Impact sites (19.3 ± 0.5 SE) was very similar, and consistent with previous surveys, there were differences in richness amongst assemblages at some locations between dredging phases. Highly consistent results were also observed in comparisons of pooled abundance for both Control (73.6 ± 7.0 SE) and Impact (70.0 ± 5.8 SE) sites, suggesting no evidence of impacts from dredging. Indeed, species richness was generally higher during Dredging surveys than Baseline surveys, although it should be noted that no Baseline surveys were undertaken during the wet season. Overall, there were no statistically significant differences found between Control and Impact sites, for any assemblage or between the Baseline or Dredging Phases indicating there was no evidence from impacts of dredging on faunal richness. Patterns in faunal abundance in D5 showed overall abundance was lower in the Hinterland Margin (24.0 ± 5.5 SE) and Tidal Flat (49.2 ± 4.3 SE) assemblages than in D3 (April/May 2013), but similar to the number of animals sampled in the Hinterland Margin (17.6 ± 2.8 SE) and Tidal Flat (65.17 ± 6.3 SE) during the same seasonal period (i.e. D1, October/November 2012). This suggests that changes in faunal abundance were also associated with natural seasonal factors. It is noteworthy that in D5 there was a greater mean abundance of fauna in the Impact sites compared to Control sites in two of the four assemblages. It was particularly evident in the Seaward assemblage, where this pattern has been consistent for all surveys in the Dredging Phase. This effect was not driven by particular taxa and was generally observed in all of the faunal groups monitored. Baseline Phase surveys were conducted during the dry season only and Dredging Phase surveys have now been conducted in both seasons. Other studies conducted using the same methodology in Darwin Harbour (Metcalfe 2007; EcoScience 2010) have noted similar seasonal patterns with consistently higher species richness and abundance during the wet season, with effects most pronounced in the two landward assemblages (i.e. Hinterland Margin and Tidal Flat). The 393 species recorded from the ten monitoring sites during all surveys appear representative of mangrove dependent fauna in Darwin Harbour as reported in Metcalfe (2007) and EcoScience NT (2012). The proportion of different taxonomic groups sampled to date (26% crustaceans, 27% molluscs and 26% worms) is also characteristic of Darwin Harbour mangrove fauna (Metcalfe 2010). Mangrove community health monitoring surveys to date have documented a substantial number of new taxonomic records for Darwin Harbour mangroves habitats (68 species to date) and several new species records for the Northern Territory and one for Australia. Similar to previous surveys, new faunal records continue to increase, with nine new species records for mangrove habitats of Darwin Harbour being recorded during D5 (Figure 5-1). A) B) C) Figure 5-1 Three of the nine new taxonomic records sampled in Darwin Harbour mangrove during the D5 survey: A) Psedoliotia sp. 2 B) Mysidacea sp.; and C) Penaeidae sp. Similar to previous surveys, species composition based on presence/absence (all species) data showed little distinction between Control and Impact sites and between B1/B2 and D5. In accordance with patterns established during previous studies in mangroves of Darwin Harbour (Metcalfe 2007; EcoScience NT 2010, 2012), clear distinctions were observed between the four different assemblages. As found in D2 and D3, there were also differences between the Baseline and Dredging Phases for most assemblages. The observed differences in composition between the Baseline and Dredging Phases are considered to be a seasonal or other widespread temporal effect (i.e. influencing all sites and assemblages). During D3 the introduced ant, Pheidole megacephala was recorded at Site I2 (Bleesers Creek), however, faunal sampling during the D5 survey failed to produce further records of this species. Significance of P. megacephala was previously discussed in the D3 report (Cardno and EcoScience NT 2013c). Prepared for INPEX Cardno Page 48

60 6 Conclusions Dredging for Season One of the East Arm dredging component of the Project was completed on 30 April 2013, therefore no dredging took place for a two month period prior to D5 (October/November 2013) data collection. There were no exceedances of the Level 2 mangrove community health triggers during the D5 survey, with results for all indicators well below trigger levels. Net change (pooled Impact polled Control sites) in canopy cover between B2 (July/August 2012) and D5 was -1.0%. Net seedling survival (pooled Impact pooled Control sites) was -8.0%, and net change in seedling growth was 1.0% based on leaf counts, and -3.8% based on node counts. Although there was an overall decline in canopy cover, seedling survival and growth based on nodes at Impact sites relative to Control sites, the magnitude of change was small and most likely mainly due to natural spatial and temporal variability in ecological and environmental factors affecting mangrove condition and recruitment processes. Monitoring of seedling growth through leaf and node counts showed continued growth at both Control and Impact sites, while senescence of seedlings had also continued in all assemblages at most sites. For individual sites there was large variability in seedling numbers, and survival rates, with high attrition rates at some assemblages and sites. Similar to previous surveys in this monitoring program, there were significant differences in flora indicators among the four different assemblages. There is no evidence of dredge related impacts on mangrove flora indicators. The only significant relationship detected between intertidal sedimentation and any of the key flora indicators showed increased growth associated with higher levels of sedimentation. This is supported by measurement of intertidal sedimentation for D5 (Cardno 2013b), which indicates levels of net sedimentation since B2 (July/August 2012) in all sites have been below the level that may start to impact mangrove health (i.e. 50 mm). Quarterly monitoring of mangrove fauna during D5 revealed an overall slight increase in faunal diversity and abundance; however, there were differences between the Baseline and Dredging Phases in the relative change in species richness, abundance and composition at some locations in some assemblages. The majority of these differences appear to be in response to marked seasonal variation in environmental conditions such as rainfall, salinity and frequency of inundation (from dry to wet season). No significant correlations could be detected in analyses examining the relationship between net sedimentation and faunal species richness, abundance and species composition. In summary, monitoring results demonstrated that no Level 2 triggers were exceeded during D5 (October/November 2013) and there were no indications that the small amounts of sedimentation at some sites have had an effect on key mangrove health indicators for any assemblages at monitoring sites. Prepared for INPEX Cardno Page 49

61 7 Acknowledgements This report was written by Jo Buckee, Dr Kristin Metcalfe, Adam Bourke, Dr Kerry Beggs and Joanna Browne, and reviewed by Dr Russell Hanley and Joanna Lamb. Data processing and presentation was done by Adam Bourke and Billy Li and the statistical analyses for flora and fauna were done by Dr Kerry Beggs. Field work was undertaken by Kristin Metcalfe, Adam Bourke, Dan Aveling, Carmen Walker and Ivon Sebastian. Specialist input for invertebrate taxonomy was provided by Professor Alan Andersen, Magen Pettit (CSIRO), Dr Richard Willan, Dr Michael Hammer, Dr Chris Glasby (MAGNT) and Peter Davie (Queensland Museum). Jo Buckee and Chris Holloway provided technical support and management of the Project. HSE support in Darwin was facilitated by Todd Sinclair and Erica Griffiths was Project Safety Officer. Prepared for INPEX Cardno Page 50

62 8 References Anderson, M.J., Gorley, R.N. and Clarke, K.R. (2008). PERMANOVA+ for Primer: Guide to Software and Statistical Methods. Primer-E Ltd, Plymouth. Bilyard, G. R. (1987). The value of benthic infauna in marine pollution monitoring studies. Marine Pollution Bulletin, 18, pp Brocklehurst, P. and Edmeades, B. (1996). The mangrove communities of Darwin Harbour. Technical Memorandum No.R96/9. Resource Capability Assessment Branch, Department of Lands, Planning and Environment, Darwin, Northern Territory. Cardno (2013a). Ichthys Project: Nearshore Environmental Monitoring Plan, Rev. 2. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney. Cardno (2013b). Quarterly Intertidal Sedimentation Dredging Report 5. Ichthys Project Nearshore Environmental Monitoring Program. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney. Cardno (2013c). Mangrove Community Health Remote Sensing Baseline Report. Ichthys Project Nearshore Environmental Monitoring Program. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney. Cardno (2013d). Mangrove Community Health Remote Sensing Report 1. Ichthys Project Nearshore Environmental Monitoring Program. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney. Cardno (2013e). Mangrove Community Health Remote Sensing Report 4. Ichthys Project Nearshore Environmental Monitoring Program. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney. Cardno and EcoScience NT (2012). Mangrove Community Health Monitoring Program Baseline Report. Ichthys Project Nearshore Environmental Monitoring Program. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney and EcoScience NT. Cardno and EcoScience NT (2013a). Mangrove Community Health Monitoring Program Dredging Report 1. Ichthys Project Nearshore Environmental Monitoring Program. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney and EcoScience NT. Cardno and EcoScience NT (2013b). Mangrove Community Health Monitoring Program Dredging Report 2. Ichthys Project Nearshore Environmental Monitoring Program. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney and EcoScience NT. Cardno and EcoScience NT (2013c). Mangrove Community Health Monitoring Program Dredging Report 3. Ichthys Project Nearshore Environmental Monitoring Program. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney and EcoScience NT. Cardno and EcoScience NT (2013d). Mangrove Community Health Monitoring Program Dredging Report 4. Ichthys Project Nearshore Environmental Monitoring Program. Report for INPEX. Prepared by Cardno (NSW/ACT) Pty Ltd, Sydney and EcoScience NT. Clark PJ (2004). Effects of experimental canopy gaps on mangrove recruitment: lack of habitat partitioning may explain stand dominance. Journal of Ecology, 92, pp Duke N.C. (2001). Gap creation and regenerative processes driving diversity and structure of mangrove ecosystems. Wetland Ecology and Management, 9, pp EcoScience NT (2010). Darwin LNG Plant. Mangrove Monitoring Program - Mangrove Invertebrate Fauna. Report prepared for URS Australia and Conoco Phillips Pty Ltd by EcoScience, pp. 63. EcoScience NT (2012.) Darwin - Weddell Baseline Environmental Studies - Mangrove Fauna. Report prepared for Northern Territory Government, Department of Lands and Planning, Land Development & Infrastructure, pp. 61. Ellison, A.M., Farnsworth, E.J. (1993). Seedling survivorship, growth and response to disturbance in Belizean mangal. American Journal of Botany, 80, pp Ellison, J.C. (1998). Impacts of sediment burial on mangroves. Marine Pollution Bulletin, 37, pp Grall, J., and Glemarec, M. (1997).Using biotic indices to estimate macrobenthic community perturbations in the Bay of Brest. Estuarine, Coastal and Shelf Science, 44, pp INPEX (2011). Ichthys Gas Field Development Project - Draft Environmental Impact Statement. INPEX Operations Australia Pty Ltd. INPEX (2012). Ichthys Gas Field Development Project - Dredging and Spoil Disposal Management Plan East Arm Rev. 1. INPEX Operations Australia Pty Ltd. INPEX (2013a). Ichthys Gas Field Development Project - Dredging and Spoil Disposal Management Plan Gas Export Pipeline Rev. 4. INPEX Operations Australia Pty Ltd. INPEX (2013b). Ichthys Project: Nearshore Environmental Monitoring Plan Addendum 03B: Dry Season Intertidal Sedimentation and Mangrove Community Health Monitoring Program. Prepared for IPDEP May Prepared for INPEX Cardno Page 51

63 Krauss, K. W., Lovelock, C. E., McKee, K. L., Lopez-Hoffman, L., Ewe, S. M. L., and Sousa, W. P. (2008). Environmental drivers in mangrove establishment and early development: A review, Aquatic Botany, 89, pp McGuinness, K.A. (2003). The mangrove forests of Darwin Harbour: a review of research on the flora and invertebrate fauna. Conference Proceedings: Darwin Harbour Region: Current Knowledge and Future Needs pp Metcalfe, K. (2007). The Biological Diversity, Recovery from Disturbance and Rehabilitation of Mangroves, Darwin Harbour, NT. Charles Darwin University, PhD thesis: Darwin. (Available on-line at Metcalfe, K. (2010). Mangrove Invertebrate Fauna. Darwin LNG Project Mangrove Monitoring Program, 2010 Report. Prepared for ConocoPhillips Australia Pty Ltd and URS Australia by EcoScience NT. Moverley, J. (2000). Estuarine health assessment using benthic macrofauna. Rivers for the future, Museum of Victoria: 1-4. Saenger P. (2002). Mangrove Ecology, Silviculture and Conservation. Kluwer Academic Publishers. Smith T.J. (1987). Effects of light and intertidal position on seedling survival and growth in tropical tidal forests. Journal of Experimental Marine Biology and Ecology, 110, pp Stickler, G.S. (1959). Use of the densitometer to estimate density of forest canopy on permanent sample plots. US Forestry Service, pp Thampanya U. (2006). Mangroves and Sediment dynamics along the coasts of southern Thailand. Taylor and Francis. pp Thampanya U., Vermaat, J.E. and Terrados J. (2002). The effect of increasing sediment accretion on the seedlings of three common Thai mangrove species. Aquatic Botany, 74, pp Wightmann, G. (2006). Mangroves of the Northern Territory, Australia. Identification and Traditional Use. Northern Territory Botanical Bulletin No. 3. Department of Natural Resources, Environment and the Arts and Greening Australia. pp Prepared for INPEX Cardno Page 52

64 Ichthys Nearshore Environmental Monitoring Program APPENDIX A INTERTIDAL SEDIMENTATION AND MANGROVE HEALTH TRIGGER ACTION RESPONSE PLAN Prepared for INPEX Cardno Page 53

65 Appendix A Intertidal Sedimentation and Mangrove Health Trigger and Response plan (Excerpt from DSDMP) Component Normal situation Level 1 Trigger Level 2 Triggers Level 3 Trigger Sedimentation Sedimentation Canopy cover Seedling survivorship and growth Mangrove area decline Trigger value Not triggered >50 mm net sedimentation OR Predicted net sedimentation rate* >50 mm/year >50 mm net sedimentation; OR Predicted net sedimentation rate* >50 mm/year; >30% net change in canopy cover; AND >50% net change in seedling survivorship and growth. Significantly deterioration of mangrove canopy cover in excess of 42 ha of derived from a minimum vegetation index value. OR Trigger description N/A Sedimentation will be measured at each of the impact and control monitoring sites. Net sedimentation will be determined by calculating the difference between measured and baseline bed level. Data collected from each assemblage in each impact site will be compared against its baseline level to determine whether sedimentation has increased since baseline. Sedimentation during dredging will be placed in context of what is naturally occurring over time by subtracting pooled changes in sedimentation at control sites. The result will be statistically compared against the trigger value. Level 1 sedimentation trigger occurs when >50 mm of sedimentation is measured (excess to control) at any assemblage at any site. OR When the predicted rate of net sedimentation measured during three previous consecutive surveys predicts sedimentation to be >50 mm/year (excess to control) at any assemblage at any site. Sedimentation will be measured at each of the impact and control monitoring sites. Data collected from each assemblage in each impact site will be compared against its baseline level to determine whether sedimentation has increased since baseline. Sedimentation during dredging will be placed in context of what is naturally occurring over time by subtracting pooled changes in sedimentation at control sites. The result will be statistically compared against the trigger value. Level 2 sedimentation trigger occurs when >50 mm of average sedimentation is measured (excess to control) within a mangrove assemblage for all impact sites. OR When the predicted rate of net sedimentation measured over a minimum of three previous consecutive monitoring surveys exceeds >50 mm/year (i.e. clear upward trend) within an assemblage for all impact sites. To be considered a Level 2 exceedance, the sedimentation level or predicted net sedimentation rate must also a) exceed 50 mm at a minimum of three sites; and b) be determined through measurements at additional contingency stakes installed along the transect (in between standard measurement stakes) and perpendicular to the existing transect locations. OR Canopy cover / seedling survivorship and growth will be measured at each of the impact and control monitoring sites. The minimum vegetation index value will be 20% below the minimum recorded site specific vegetation index value derived from analysis of >10 year data sets of Landsat imagery. Consideration of reference areas will be included in the determination of ecological significance of a Level 3 trigger exceedance. Prepared for INPEX Cardno Page 54

66 Component Normal situation Level 1 Trigger Level 2 Triggers Level 3 Trigger Sedimentation Sedimentation Canopy cover Seedling survivorship and growth Net change in canopy cover / seedling survivorship and growth will be determined by calculating the difference between measured and baseline data. Net change in canopy cover / seedling survivorship and growth from impact sites and control sites will be pooled and the difference between the two will be tested against the trigger value. Where a Level 2 trigger exceedance is identified a consideration of natural range of variability in canopy / seedling survivorship and growth cover from baseline data will be made prior to management responses be implemented. Mangrove area decline Monitoring response (Monitoring Contractor) Routine intertidal sedimentation and mangrove health monitoring (quarterly basis) Implement reactive intertidal sedimentation monitoring (same methods and sites as for routine monitoring) on a monthly basis only during dredging and spoil disposal activities. Monthly monitoring will continue for a minimum of 3 months to establish a clear understanding of the predicted net sedimentation rate. Resume routine intertidal monitoring once net sedimentation rates are similar to the rates at control sites, or not significantly greater than the range of rates observed during baseline monitoring. Implement reactive intertidal sedimentation monitoring (same methods and sites as for routine monitoring) on a monthly basis only during dredging and spoil disposal activities. AND Implement reactive mangrove health monitoring (same methods and sites as for routine monitoring) at next earliest opportunity (probably the next spring tide) only during dredging and spoil disposal activities. Frequency of mangrove monitoring going forward will then be determined. Resume routine monitoring (intertidal sedimentation and mangrove health on a quarterly basis) once net sedimentation rates are similar to the rates at the reference sites, or not significantly different to the range of rates observed at the impact site during the baseline AND Canopy cover and seedling survivorship and growth returns to below Trigger Level 2 value OR Management response (including mangrove rehabilitation plans / actions) is deemed appropriate to allow return to routine monitoring. Prepared for INPEX Cardno Page 55

67 Ichthys Nearshore Environmental Monitoring Program APPENDIX B METHOD DETAILS Prepared for INPEX Cardno Page 56

68 Appendix B-1 Method Details Flora Table B-1 Summary of calculations used for MCH indicators Metric Unit Basic level of replication Calculation Method N at plot level Canopy Cover Canopy cover % Densiometer position Percentage canopy cover calculated from 48 readings taken at three randomly placed replicate densiometer positions in each of four subplots 12 Change in % canopy cover (survey relative to B2 (July/August 2012) ) % Subplot Change in average percentage canopy cover (survey minus B2 (July/August 2012)) 4 Seedling and Sapling Densities (data collected in random 1 m x 1 m quadrats) Seedling density No./m 2 Random quadrat Counts of seedlings in two randomly placed quadrats per subplot 8 Seedling density change (survey relative to B2 (July/August 2012) ) No./m 2 Subplot Change in count of seedlings per subplot (survey minus B2 (July/August 2012)) 4 Sapling density No./m 2 Random quadrat Counts of saplings in two randomly placed quadrats per subplot 8 Sapling density change (survey relative to B2 (July/August 2012) ) No./m 2 Subplot Change in count of saplings calculated per subplot 4 Seedling richness No. Plot Total number of seedling species per plot (pooled from eight quadrats per plot) Sapling richness No. Plot Total number of sapling species per plot (pooled from eight quadrats per plot) 1 1 Seedling Survival (data collected in permanent 1 m x 1 m quadrats) Number of live seedlings No. Permanent quadrat Count of individually identified seedlings surviving since B2 (July/August 2012) (excluding seedlings recruited since B2 (July/August 2012)) in each of five permanent quadrats 5 Survival (survey relative to B2 (July/August 2012) ) % Permanent quadrat Number of live seedlings expressed as a percentage of the original count of seedlings in B2 (July/August 2012), calculated for each five permanent quadrats 5 Seedling Growth (data collected in permanent 1 m x 1 m quadrats) Number of leaves No. Permanent quadrat Count of total number of leaves on of individually identified seedlings surviving since B2 (July/August 2012) (excluding seedlings recruited since B2 (July/August 2012)) in each of five permanent quadrats 5 Leaves per plant No./pla nt Individual plant Number of leaves divided by the number of live seedlings, calculated for each five permanent quadrats = number of plants (varies) Net leaf change (survey relative to B2 (July/August 2012) ) No. Individual plant Change in number of leaves calculated for each plant (survey minus B2 (July/August 2012)) = number of plants (varies) Prepared for INPEX Cardno Page 57

69 Metric Unit Basic level of replication Calculation Method N at plot level Percentage leaf change (survey relative to B2 (July/August 2012) ) % Individual plant Change in number of leaves (survey minus B2 (July/August 2012) ) expressed as a percentage of the original count of leaves in B2 (July/August 2012), calculated for each surviving plant = number of plants (varies) Number of nodes No. Permanent quadrat Count of total number nodes on of individually identified Rhizophoraceae seedlings surviving since B2 (July/August 2012) (excluding seedlings recruited since B2 (July/August 2012)) in each of five permanent quadrats 5 Nodes per plant No./pla nt Individual plant Number of nodes divided by the number of live seedlings, calculated for each five permanent quadrats = number of plants (varies) Net nodal change (survey relative to B2 (July/August 2012) ) No. Individual plant Change in number of nodes calculated for each plant (survey minus B2 (July/August 2012)) in five permanent quadrats for each plot = number of plants (varies) Percentage nodal change (survey relative to B2 (July/August 2012) ) % Individual plant * Number used for calculation of standard errors at plot level. Change in number of nodes (survey minus B2 (July/August 2012)) expressed as a percentage of the original count of leaves in B2 (July/August 2012), calculated for each surviving plant = number of plants (varies) Prepared for INPEX Cardno Page 58

70 Appendix B-2 Monitoring Schedule Fauna B-2 A: Dredging Survey 5a, 17 October 2013 to 26 October 2013 Site Number Site Name Date (2013) Tasks I1 Bayview 17-Oct Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. I1 Bayview 18- Oct Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. C3 Middle Arm 19-Oct Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. C3 Middle Arm 20-Oct Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. I5 Eliz River- Creek 21-Oct Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. I5 Eliz River- Creek 22-Oct Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. I2 Bleesers Creek 23-Oct Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. I2 Bleesers Creek 24-Oct Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. C4 Blackmore Boat ramp 25-Oct Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. C4 Blackmore Boat ramp 26-Oct Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. Prepared for INPEX Cardno Page 59

71 B-2 B: Dredging Survey 5b, 1 to 11 November 2013 Site Number Site Name Date (2013) Tasks I4 Blaydin Point 1-Nov Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. I4 Blaydin Point 2-Nov Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. C2 Channel Is 3-Nov Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. C2 Channel Is 4-Nov Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. I3 East Arm Boat ramp 5-Nov Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. I3 East Arm Boat ramp 6-Nov Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. I6 Upstream Eliz River 7-Nov Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. I6 Upstream Eliz River 8-Nov Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. C1 Woods Inlet 9-Nov Sample fauna (install pitfall traps and anoxic mats). Measure seedling growth and survival. Photomonitoring. Sample quadrat fauna. C1 Woods Inlet 10-Nov Check and retrieve pitfall traps and anoxic mats. Densiometer readings. Seedling recruitment. Complete fauna sampling in quadrats. C1 Woods Inlet 11-Nov Pack up and return to Darwin. Demobilisation. Prepared for INPEX Cardno Page 60

72 Ichthys Nearshore Environmental Monitoring Program APPENDIX C TIME SERIES RESULTS BY ASSEMBLAGE/SITE Prepared for INPEX Cardno Page 61

73 Appendix C-1 Canopy Cover Mean percentage a) canopy cover (±SE) and b) change in percentage canopy cover relative to B2 (July/August 2012) for each site measured in health plots within each assemblage/zone Prepared for INPEX Cardno Page 62

74 Prepared for INPEX Cardno Page 63

75 Prepared for INPEX Cardno Page 64

76 Prepared for INPEX Cardno Page 65

77 Prepared for INPEX Cardno Page 66

78 Appendix C-2 Random Seedling and Sapling Mean Density Per Quadrat Random seedling data for sites showing a) mean number of seedlings (±SE) per m 2 quadrat, b) change in seedlings (±SE) per m 2 quadrat between B2 and D5 c) mean number of saplings (±SE) per m 2 quadrat, measured in mangrove community health plots within each assemblage/zone d) change in saplings (±SE) per m 2 quadrat between B2 and D5 a) b) c) d) Prepared for INPEX Cardno Page 67

79 a) b) c) d) Prepared for INPEX Cardno Page 68

80 a) b) c) d) Prepared for INPEX Cardno Page 69

81 a) b) c) d) Prepared for INPEX Cardno Page 70

82 a) b) c) d) Prepared for INPEX Cardno Page 71

83 a) b) c) d) Prepared for INPEX Cardno Page 72

84 a) b) c) d) Prepared for INPEX Cardno Page 73

85 a) b) c) d) Prepared for INPEX Cardno Page 74

86 a) b) c) d) Prepared for INPEX Cardno Page 75

87 a) b) c) d) Prepared for INPEX Cardno Page 76

88 Appendix C-3 Individual seedling growth and survival data for sites showing a) mean number of seedlings (±SE) per assemblage, b) percentage survival (±SE), c) total number of leaves (±SE), d) average percentage leaf change (±SE), e) mean number of nodes per plant, f) average percentage node change (±SE), measured in mangrove community health plots within each assemblage/zone a) b) c) d) e) f) Prepared for INPEX Cardno Page 77

89 a) b) c) d) e) f) Prepared for INPEX Cardno Page 78

90 a) b) c) d) e) f) Prepared for INPEX Cardno Page 79

91 a) b) c) d) e) f) Prepared for INPEX Cardno Page 80

92 a) b) c) d) e) f) Prepared for INPEX Cardno Page 81

93 a) b) c) d) e) f) Prepared for INPEX Cardno Page 82

94 a) b) c) d) e) f) Prepared for INPEX Cardno Page 83

95 a) b) c) d) e) f) Prepared for INPEX Cardno Page 84

96 a) b) c) d) e) f) Prepared for INPEX Cardno Page 85

97 a) b) c) d) e) f) Prepared for INPEX Cardno Page 86

98 Ichthys Nearshore Environmental Monitoring Program APPENDIX D STATISTICAL ANALYSES FLORA Prepared for INPEX Cardno Page 87

99 Appendix D-1 Canopy Cover Analyses D-1 A: PERMANOVA analysis for Canopy Cover Five-factor nested PERMANOVA comparing canopy cover (average of 4 densiometer readings taken at N, S, E, and W corners of each subplot) between Phases (fixed, 2 levels Baseline and Dredging), Surveys (random, nested in Phase, 7 levels), Treatment (fixed, 2 levels), Assemblage (fixed, 4 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface. Redundant term due to significant interaction (RED) Source of variation df SS MS Pseudo-F P(perm) Phase Treatment Assemblage RED Survey(Phase) Location(Treatment) RED Phase x Treatment Phase x Assemblage RED Treatment x Assemblage Phase x Location(Treatment) Treatment x Survey(Phase) Assemblage x Survey(Phase) Assemblage x Location(Treatment)** RED Phase x Treatment x Assemblage Survey(Phase)x Location(Treatment) Phase x Assemblage x Location(Treatment)** Treatment x Assemblage x Survey(Phase) Assemblage x Survey(Phase) x Location(Treatment)** Residual E Total E5 ** Term has one or more empty cells (i.e. at some Locations, not all four Assemblages were sampled) Prepared for INPEX Cardno Page 88

100 Appendix D-1 Canopy Cover Analyses. Continued D-1 B: Post-Hoc Test for Canopy Cover Post-hoc permutational t-tests for the term Phase x Treatment for canopy cover. Statistically significant results (p<0.05) are denoted by bold type Canopy cover Pair-wise Comparison t P(perm) t P(perm) Treatment pairs Baseline Dredging Control vs Impact Phase pairs Control Impact Baseline vs Dredging D-1 C: Canopy Cover plot illustrating significant Phase x Treatment interaction Mean percentage canopy cover (± SE) at Control and Impact sites during Baseline and Dredging Phases. Percentage canopy cover (+/- SE) Treatment Control Impact 80 Phase Baseline Dredging Prepared for INPEX Cardno Page 89

101 Appendix D-1 Canopy Cover Analyses. Continued D-1 D: T-Test for Canopy Cover Trigger Assessment Canopy Cover Trigger Assessment. Samples are difference in % canopy cover between D5 and B2, for Control and Impact sites Statistic / Test Control Impact Test Conclusion Sample statistics Mean Difference = 1.05 Variance n F test H 0: variances are equal F calculated 0.23 F critical (one tailed, df = 59, 91, α = 0.05) 0.67 P <0.001 H 0 rejected; variances are unequal t test H 0: difference between means = zero t calculated (Welch s) 1.13 t critical (two-tailed, df = 146, α = 0.05) 1.97 P 0.26 H 0 accepted: zero difference between means t-test H A: difference between means = 30%. N/A Prepared for INPEX Cardno Page 90

102 Appendix D-2 Seedling and Sapling Density Analyses D-2 A: PERMANOVA analysis for seedling density Five-factor nested PERMANOVA comparing seedling density between Phases (fixed, 2 levels), Surveys (random, nested in Phase, 7 levels), Treatment (fixed, 2 levels), Assemblage (fixed, 4 levels) and Location (random, nested in Treatment, 10 levels). Seedling density was log transformed using x = log e (x+1). Statistically significant results (P<0.05) are denoted by boldface and redundant terms due to significant interaction (RED) Source of variation df SS MS Pseudo-F P(perm) Phase Treatment Assemblage RED Survey(Phase) RED Location(Treatment) RED Phase x Treatment Phase x Assemblage RED Treatment x Assemblage Phase x Location(Treatment) RED Treatment x Survey(Phase) Assemblage x Survey(Phase) Assemblage x Location(Treatment)** RED Phase x Treatment x Assemblage E Survey(Phase) x Location(Treatment) Phase x Assemblage x Location(Treatment)** Treatment x Assemblage x Survey(Phase) Assemblage x Survey(Phase) x Location(Treatment)** Residual Total ** Term has one or more empty cells Prepared for INPEX Cardno Page 91

103 Appendix D-2 Seedling and Sapling Density Analyses. Continued D-2 B: PERMANOVA for Sapling density Five-factor nested PERMANOVA comparing sapling density between Phases (fixed, 2 levels), Surveys (random, nested in Phase, 7 levels), Treatment (fixed, 2 levels), Assemblage (fixed, 4 levels) and Location (random, nested in Treatment, 10 levels). Seedling density was log transformed using x = log e (x+1). Statistically significant results (P<0.05) are denoted by boldface. Redundant term due to significant interaction (RED) Source of variation df SS MS Pseudo-F P(perm) Phase RED Treatment Assemblage RED Survey(Phase) Location(Treatment) RED Phase x Treatment E E Phase x Assemblage Treatment x Assemblage Phase x Location(Treatment) Treatment x Survey(Phase) E Assemblage x Survey(Phase) Assemblage x Location(Treatment)** Phase x Treatment x Assemblage Survey(Phase) x Location(Treatment) Phase x Assemblage x Location(Treatment)** Treatment x Assemblage x Survey(Phase) E Assemblage x Survey(Phase) x Location(Treatment)** Residual Total ** Term has one or more empty cells Prepared for INPEX Cardno Page 92

104 Appendix D-3 Seedling Growth and Survival Analyses D-3 A: PERMANOVA for Change in Leaf Counts for all species combined Three-factor nested PERMANOVA comparing change in leaf counts for all species combined from Survey 2 (B2 ) to Survey 7 (D5) between Treatment (fixed, 2 levels), Assemblage (fixed, 4 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface. Source df SS MS Pseudo-F P(perm) Treatment Assemblage Location(Treatment) Treatment x Assemblage Location(Treatment) x Assemblage** Residual Total ** Term has one or more empty cells D-3 B: T-Test for Change in Leaf Count Trigger assessment Leaf Counts Trigger Assessment. Samples are difference in leaf counts between D5 and B2, for Control and Impact sites (for all species combined) Statistic / Test Control Impact Test Conclusion Sample statistics Mean Difference = 1.0 Variance n F test H 0: variances are equal F calculated 0.74 F critical (one tailed, df = 538, 803, α = 0.05) 0.88 P H 0 rejected: variances are unequal t test H 0: difference between means = 0 t calculated (Welch s) 0.27 t critical (two-tailed, df = 1259, α = 0.05) 1.96 P 0.79 t-test H A: difference between means = 50%. H 0 accepted: zero difference between means N/A Prepared for INPEX Cardno Page 93

105 D-3 C: PERMANOVA for Change in Leaf Counts for Aegiceras corniculatum Two-factor nested PERMANOVA comparing change in leaf counts for Aegiceras corniculatum (Seaward assemblage dominant) from Survey 2 (B2) to Survey 7 (D5) between Treatment (fixed, 2 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface Source df SS MS Pseudo-F P(perm) Treatment E Location(Treatment) Residual Total D-3 D: PERMANOVA for Change in Leaf Counts for Rhizophora stylosa Two-factor nested PERMANOVA comparing change in leaf counts for Rhizophora stylosa (Tidal Creek assemblage dominant) from Survey 2 (B2) to Survey 7 (D5) between Treatment (fixed, 2 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface Source df SS MS Pseudo-F P(perm) Treatment E Location(Treatment) Residual Total NB: from 44 plants only (33 from 4 Control Locations, 11 from 2 Impact Locations). D-3 E: PERMANOVA for Change in Leaf Counts for Bruguiera parviflora Two-factor nested PERMANOVA comparing change in leaf counts for Bruguiera parviflora (Tidal Creek assemblage dominant) from Survey 2 (B2) to Survey 7 (D5) between Treatment (fixed, 2 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface Source df SS MS Pseudo-F P(perm) Treatment Location(Treatment) Residual Total Prepared for INPEX Cardno Page 94

106 D-3 F: PERMANOVA for Change in Leaf Counts for Ceriops australis Three-factor nested PERMANOVA comparing change in leaf counts for Ceriops australis (recorded in Tidal Flat and Hinterland margin assemblages) from Survey 2 (B2) to Survey 7 (D5) between Treatment (fixed, 2 levels), Assemblage (fixed, 2 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface Source df SS MS Pseudo-F P(perm) Treatment Assemblage Location(Treatment) Treatment x Assemblage Location(Treatment) x Assemblage** Residual Total ** Term has one or more empty cells D-3 G: PERMANOVA for Change in Node Counts for all species combined Three-factor nested PERMANOVA comparing change in node counts for all species combined from Survey 2 (B2) to Survey 7 (D5) between Treatment (fixed, 2 levels), Assemblage (fixed, 3 levels Seaward excluded) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface Source df SS MS Pseudo-F P(perm) Treatment Assemblage Location(Treatment) Treatment x Assemblage Location(Treatment) x Assemblage** Residual Total ** Term has one or more empty cells Prepared for INPEX Cardno Page 95

107 D-3 H: T-Test for Node Count Trigger Assessment. Samples are difference in node counts between D5 and B2, for Control and Impact sites (for all species combined) Statistic / Test Control Impact Test Conclusion Sample statistics Mean Difference = -3.2 Variance n F test H 0: variances are equal F calculated F critical (one tailed, df = 204, 436, α = 0.05) 1.24 P <0.001 t test H 0: difference between means = 0 t calculated (Welch s) 0.36 t critical (two-tailed, df = 251, α = 0.05) 1.97 P 0.72 t-test H A: difference between means = 50%. H 0 rejected; variances are unequal H 0 accepted: zero difference between means N/A D-3 I: PERMANOVA for Change in Node Counts for Rhizophora stylosa Two-factor nested PERMANOVA comparing change in node counts for Rhizophora stylosa (Tidal Creek assemblage dominant) from Survey 2 (B2) to Survey 7 (D5) between Treatment (fixed, 2 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by bold type Source df SS MS Pseudo-F P(perm) Treatment Location(Treatment) Residual Total NB from only 13 plants (8 from 2 Control, and 5 from 2 Impact Locations only) Prepared for INPEX Cardno Page 96

108 D-3 J: PERMANOVA for Change in Node Counts for Bruguiera parviflora Two-factor nested PERMANOVA comparing change in node counts for Bruguiera parviflora (Tidal Creek assemblage dominant) from Survey 2 (B2) to Survey 7 (D5) between Treatment (fixed, 2 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface Source df SS MS Pseudo-F P(perm) Treatment Location(Treatment) Residual Total D-3 K: PERMANOVA for Change in Node Counts for Ceriops australis Three-factor nested PERMANOVA comparing change in node counts for Ceriops australis (recorded in Tidal Flat and Hinterland margin assemblages) from Survey 2 (B2) to Survey 7 (D5) between Treatment (fixed, 2 levels), Assemblage (fixed, 2 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface Source df SS MS Pseudo-F P(perm) Treatment Assemblage Location(Treatment) Treatment x Assemblage Location(Treatment) x Assemblage** Residual Total ** Term has one or more empty cells D-3 L: PERMANOVA for Seedling Survival Three-factor nested PERMANOVA comparing seedling survival (%) from Survey 2 (B2) to Survey 7 (D5), between Treatment (fixed, 2 levels), Assemblage (fixed, 4 levels) and Location (random, nested in Treatment, 10 levels). Statistically significant results (P<0.05) are denoted by boldface Source df SS MS Pseudo-F P(perm) Treatment Assemblage Location(Treatment) RED Treatment x Assemblage Location(Treatment) x Assemblage** Residual Total E5 ** Term has one or more empty cells Prepared for INPEX Cardno Page 97

109 D-3 M: T-Test for Seedling Survival Trigger Assessment Samples are seedling survival (difference in seedling counts between B2 and D5, expressed as a % of B2), for Control and Impact sites (for all species combined) Statistic / Test Control Impact Test Conclusion Sample statistics Mean Difference = -7.6 Variance n F test H 0: variances are equal F calculated 1.01 F critical (one tailed, df = 74, 114, α = 0.05) 1.41 P 0.47 H 0 accepted; variances are equal t test H 0: difference between means = 0 t calculated (Student s) 1.79 t critical (two-tailed, df = 186, α = 0.05) 1.97 P 0.08 H 0 accepted: zero difference between means t-test H A: difference between means = 50%. N/A Prepared for INPEX Cardno Page 98

110 Quarterly Mangrove Community Health Report Dredging Report 5 Ichthys Nearshore Environmental Monitoring Program APPENDIX E PHOTO MONITORING Prepared for INPEX Cardno

111 Quarterly Mangrove Community Health Report Dredging Report 5 Appendix E-1 Photo-monitoring Impact Sites Prepared for INPEX Cardno Page 100

112 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 101

113 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 102

114 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 103

115 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 104

116 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 105

117 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 106

118 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 107

119 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 108

120 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 109

121 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 110

122 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 111

123 Quarterly Mangrove Community Health Report Dredging Report 5 Appendix E-2 Photo-monitoring Control Sites Prepared for INPEX Cardno Page 112

124 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 113

125 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 114

126 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 115

127 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 116

128 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 117

129 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 118

130 Quarterly Mangrove Community Health Report Dredging Report 5 Prepared for INPEX Cardno Page 119