Magnetic Island Summary Report 2017

Transcription

1 Summary Report 2017 Reef Check Foundation Ltd. (Australia) This report should be cited as: M. Welch, J. Salmond, J. Passenger, G. Molinaro and J. Loder (2017) Season Report Reef Check Foundation Ltd.

2 Season Report 2017 (RCA) is an environmental charity dedicated to protecting Australia s reefs and oceans by engaging the community in hands-on citizen science and education initiatives. Survey teams are part of a worldwide network of trained volunteers that regularly monitor and report on reef health in more than 90 countries using a standardized scientific survey method. The goal of Reef Check monitoring is to determine broad-scale trends of how our reefs are changing over time on both local and global scales. RCA data can provided to scientists and managers as an early warning system to supplement other monitoring programs that document changes and disturbances on the reef. Reef Check Surveys Reef Check surveys are conducted along a transect line that is laid along a constant depth and reef habitat type. The total transect length that is surveyed is 80m, divided into four 20m sections or transect replicates. A set of biological indicators was chosen for Reef Check, to serve individually as indicators of specific types of human impacts, and collectively as a proxy for ecosystem health. These indicators fall into the following categories: Percent cover of reef composition is surveyed using a point sample method with a plumbline, or weighted line. Divers record the substrate type that is directly below the tape measure every 0.5m along each of the four 20m sections interval to estimate percent cover of 25 substrate categories. Invertebrate, reef health impact and fish (when logistically suitable) abundance are documented using a 5m wide u-shaped search pattern across the transect line to search for target indicators. For additional details on monitoring methodology, please see the Monitoring Methods (Hill & Loder 2013). This initiative is proudly supported by Townsville City Council. Special thanks to all our amazing team of trained surveyors who supported the surveys in 2017: Olen Dick, Rob Holland,, Samantha Jaworski, Laura Lazar, Gemma Molinaro, Jilly Wheeler. Thank you to our Reef Check Industry Champions who provided in-kind donations to support the 2017 survey season: Adrenalin Dive, Dive Patrol, Fantasea and Pleasure Divers.

3 Season Report 2017 Monitoring Sites In 2017, volunteers visited seven sites across five areas in the region. Sites included Alma Bay (Site 1 & 2), Florence Bay, Geoffrey Bay (site 4), Middle Reef (Site 1 & 2) and Nelly Bay (Fig 1). Monitoring sites were established in various years, with the earliest site established in 2003 (Geoffrey Bay and Nelly Bay), and the latest in 2006 (Florence Bay). All sites are fringing reefs at shallow depths except Alma Bay Site 1, which lies at a medium depth of 6 meters. Figure 1. Location of monitoring sites around surveyed in Table 1. Summary table of RCA monitoring findings for surveys conducted around in the 2017 season. Information includes a basic site summary of average hard and soft coral cover (%), total macroalgae (MA) abundance, nutrient indicator algae (NIA) cover (%) and silt levels (L=low, M=medium, H=high), as well as a summary of the impacts at each site: average coral bleaching of the population (%) and abundance of reef impacts (marine debris, coral damage and coral scars). Site Summary Presence of Impacts Reefs Hard Coral Coverage (%) Soft Coral Coverage (%) Macroalgae (#) per 80m transect Nutrient Indicator Algae (%) Silt Loading Coral Population Bleaching (%) Coral Disease (#) Fishing Line (#) Marine Debris (General) (#) AnchorDamage (#) Coral Damage (#) (unknown causes) Drupella Scar (#) Crown of Thorns Scar (#) Unknown Scar (#) Alma Bay, Site M Alma Bay, Site 2 36 < M Florence Bay M Geoffrey Bay, Site L Middle Reef, Site 1 41 < L Middle Reef, Site L Nelly Bay M

4 Summary Substrate patterns The average hard coral cover for sites surveyed in 2017 was 33%, with a range from 12-60% (Fig 2). Foliose coral was the most common hard coral growth form in 2017, except at Alma Bay, S2, which was heavily populated by encrusting corals. Rock (RC) accounted for 28% of cover across all sites. Rock totals included rock with coralline algae (11%), rock with turf algae (10%), and bare rock (6%). Nutrient indicator algae closely followed rock in overall substrate composition, contributing 27% on average across all sites. Soft coral (SC) was only present at 3 of the 7 sites (Alma Bay S2, Middle Reef S1 and S2), and averaged 1% of the total substrate composition. In 2017, Sponge was also present in low quantities (1%) and was recorded at 4 of the 7 sites. At all monitoring sites except Geoffrey Bay, live coral cover (hard and soft) has consistently been under 45% in the last 5 years (Fig 3). Lower levels of coral bleaching were recorded on surveys in 2017 (3% average) compared to the 2016 season (17%). Substrate Composition (2017) HC SC BC RKC RC NIA SP OT RB SD SI 100% 90% 80% Percent Cover 70% 60% 50% 40% 30% 20% 10% 0% Figure 2. Substrate cover at all Sites for the 2017 season. Substrates recorded include hard coral (HC), soft coral (SC), bleached coral (BC), recently killed coral (RKC), rock (RC), nutrient indicating algae (NIA), sponge (SP), other (OT),rubble (RB),sand (SD) and silt (SI).

5 Summary Coral Trends During Monitoring Florence Bay Geoffrey Bay Nelly Bay Percent cover Percent cover Percent cover Alma Bay, S1 Middle Reef, S1 Alma Bay, S2 Middle Reef, S2 Figure 3. Percent cover of hard coral (dark blue), soft coral, (light blue), and bleached coral (orange) by survey year at reef health monitoring sites, as per point-intercept substrate surveys for benthic composition. Percentage of coral population exhibiting bleaching (purple dot), as documented on belt transect survey for reef health impacts, is included where available.

6 Summary Signs of Reef Stress Coral bleaching was recorded on all sites in 2017, but at low levels with only 3% of the population affected on average. The highest bleaching documented was at Florence Bay and Geoffrey Bay, where 6% of the population was bleached. In 2016, the highest bleaching impact was 58% of the coral population atmiddle Reef, S1. Other coral damage was the most common impact to corals on average (Fig 4), and was noted at all site except Alma Bay, S2. Coral scars were also recorded at four sites in 2017: Alma Bay, S1; Florence Bay; Geoffrey Bay; and Nelly Bay. Both Drupella scars and scars from unknown causes were documented at these 4 sites. Abundance Reef Impact Abundance 2017 Damage: OT Coral Disease Marine Debris Drupella Scars Only 2 counts of marine debris were recorded across all sites, both pieces found at Alma Bay, S1. Coral disease was only recorded at Geoffrey Bay with 4 marked incidents. Figure 4. Impact Abundance around in the 2017 season. For bleached coral, see Figures 2 and 3. Indicator Invertebrates The most abundant invertebrate recorded were Drupella snails (Fig 5) with a total of 36 recorded over the 7 sites. Drupella snails were also the most abundant invertebrate in 2016 (43 individuals sighted). Four giant clams were noted at Alma Bay, S2, while 2 Trochus shells were located at Alma Bay S1. 5 total anemones were found across all sites, with 1 at Alma Bay, S1, and 2 each at Florence Bay and Middle Reef, S2. Abundance Invertebrate Abundance 2017 Giant Clam Trochus Snail Drupella Snail Anemone Figure 5. Total abundance of indicator invertebrates at each of the sites sampled in 2017.

7 Mackay Summary Season Report 2017 Survey Images Images: Top to bottom, left to right: Surveyor in action, Geoffrey Bay. Drupella snail. Hard coral, Alma Bay S1. Hard coral and nutrient indicator algae, Middle Reef S1. Blue spotted ray, Nelly Bay. Bleached hard coral, Nelly Bay. For more information on, survey methods, sites and previous reports, please go to