River Ecosystem Restoration

Transcription

1 River Ecosystem Restoration Habitat Assessment Methods 'In rivers, habitat is the result of predictable physical processes and so conveniently sits between the forces which structure rivers and the biota which inhabit them' (Harper and Everard, 1998).

2 River Habitat Survey RHS Applications

3 RHS Applications Catchment evaluations Habitat suitability for species Water Framework Directive Habitats Directive Rehabilitation/restoration Flood Risk Management Environmental Impact Assessment

4 Catchment reports: Integrating Geomorphological and River Habitat Surveys (RHS) at a catchment scale Identifying the potential restoration of Goldrill Beck Joanne Barlow and Kate Cooper RHS Team, Environment Agency Data from the Environment Agency See:

5 Project objectives Evaluate habitat quality and geomorphological features Identify pressures on the system Derive options for future management

6 HQA and HMS results HQA - higher in upland areas, high quality sites also found on main rivers HMS - main rivers are more modified than tributaries

7 Targeted Restoration Measures SITE (HQA = 5) Lack of flow features and substrate diversity RESTORATION OPTIONS Relax left bank (RI) to promote sinuosity and deposition features Encourage wet woodland on right bank - wood features and leafy debris Create backwaters/refuges for fish and invertebrates during high flow

8 RHS & Habitat Management Tools Midlands Fish Communities Study Environment Agency Pilot Study into Midlands fish communities using RHS data to: Describe fish habitats Assess habitat quality Identify pressures and impacts

9 Gudgeon Eel Trout Roach Dace 100 sites electrofished and RHS undertaken 5 fish communities identified

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12 Water Framework Directive (WFD) WFD surveillance monitoring 6 yearly cycle Used to define high status for hydromorphology RHS Baseline Surveys (UK) / (Portugal) According to the WFD all waterbodies must meet good status by 2015 Implies restoration measures for many rivers and streams RHS characterisation BACI studies.

13 Energy (Height of and distance to source) Identifying WFD Reference sites for Hydromorphology Figure 3: PCA Plot of RHS Baseline and Reference Condition Sites for Hydromorphology Altitude & Slope Baseline Sites Reference Condition sites

14 Portuguese Case Study: River Odelouca compensatory restoration measures Odelouca River (Algarve, S. Portugal) 2 critically threatened endemic fish species Iberian Chub - Squalius aradensis (Coelho et al., 1998) Iberian nase Iberochondrostoma almacai (Coelho, Mesquita & Collares-Pereira, 2005) Extensive mature riparian galleries Demand for water Tourism, development Partially built dam completed and inaugurated in 2010 Valuable riparian galleries - flooded area Mandatory compensatory restoration measures See papers: offset construction impacts and loss of habitat

15 Rehabilitation of the River Odelouca (Algarve Portugal) Identify habitat quality gradients and drivers of change in potential indicator groups Identify suitable indicator organisms/groups Test restoration / rehabilitation scenarios

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17 sampling sites 500m reaches 5 upstream of future reservoir 10 area to be flooded 10 downstream of dam 5 in tributaries (Monchique, Monchicão, Carvalho)

18 DATA TRANSFORMATION & ANALYSES RIVER HABITAT SURVEY 500m reach MACROINVERTEBRATES 6 x 1m hand net drags FISH Electrofishing 20x mean reach width Relative abundance (STRUCTURE) IDENTIFY HABITAT QUALITY GRADIENTS BIRDS 500m reach + ASSESS BIOLOGICAL INDICATORS PLANTS 100m reach % coverage Metrics (FUNCTION) ENVIRONMENTAL VARIABLES PRESSURE VARIABLES TEST RESTORATION SCENARIOS (FIELD & GIS)

19 Habitat quality gradients KT Method Identify and group similar fluvial reaches Homogenous Physiogeographical Units» Geographic and hydrogeomorphological variables Hierarchy (Strahler), geology, precipitation & altitude Assess units - presence of anthropogenic pressures (K i ) Urban area, roads, point source pollution, agricultural land use, hydromorphological alteration Conservation index (KT) KT = Ki / nki Cortes R, Oliveira S, Cabral D, Santos S, Ferreira MT (2002). Archives für Hydrobiology, 13: Fernandes MR, Ferreira MT, Hughes SJ, Cortes RV, Santos JM, Pinheiro P (2007). Recurso Hídricos. 28(3):15-24

20 Determining the conservation status of reaches along the River Odelouca using KT methodology Fernandes MR, Ferreira MT, Hughes SJ, Cortes RV, Santos JM, Pinheiro P (2007). Recurso Hídricos. 28(3):15-24

21 Using data to define restoration aims Control diffuse pollution Control diffuse pollution, reestablish connectivity, control exotic vegetation, riparian restoration Control diffuse and point pollution Control of diffuse pollution, point pollution and exotic vegetation Riparian, bankside & habitat restoration Fernandes MR, Ferreira MT, Hughes SJ, Cortes RV, Santos JM, Pinheiro P (2007). Recurso Hídricos. 28(3):15-24

22 Identifying indicators What are organism groups responding to? Natural or pressure gradients Is structure or function of indicator groups a better indicator of the effect of pressures? Candidate organism group(s)? Benthic macroinvertebrates Fish Birds Macrophytes Hughes SJ, Santos JM, Ferreira MT, Caraça R, Mendes AM, (2009) Freshwater Biology (2009) 54,

23 Principal Components Analyses Revealed scale-dependent longitudinal differences separate narrower higher lying sites and tributaries with good quality habitats from more open degraded sites lower downstream. Revealed large scale pressures describing changes in land use related to agriculture with associated physical impacts to bankside and channel ENVIRONMENT PRESSURE BASIN REACH HABITAT Axis 1 Axis 2 Axis 1 Axis 2 VALLEY FORM MONOCULTURE AGRICULTURAL LAND-USE ALTITUDE BANK REINFORCED BARS BANK EMBANKED RIPARIAN WIDTH (M) NATURAL LAND-USE WATER VELOCITY BANK MODIFICATION ph BANK TOP - AGRICULTURE BANK TOP - PASTURE Hughes SJ, Santos JM, Ferreira MT, Caraça R, Mendes AM, (2009) Freshwater Biology (2009) 54,

24 Forward selection Environmental variables > Pressure variables Environmental Redundancy high between groups ph & altitude longitudinal gradient Fish highest nº environmental variables ph, altitude, bars and riparian width» habitat quality Pressure variables Poor association with functional data (metrics) Birds highest nº of pressure variables Bankside disturbance and changes in land use Hughes SJ, Santos JM, Ferreira MT, Caraça R, Mendes AM, (2009) Freshwater Biology (2009) 54,

25 Indicator organisms Fish and birds Large, mobile organisms Have good links with physical disturbance and key environmental variables Macroinvertebrates Reflected changes in flow regime Hughes SJ, Santos JM, Ferreira MT, Caraça R, Mendes AM, (2009) Freshwater Biology (2009) 54,

26 Bird structure & function Hughes SJ, Santos JM, Ferreira MT, Caraça R, Mendes AM, (2009) Freshwater Biology (2009) 54,

27 Fish structure and function Hughes SJ, Santos JM, Ferreira MT, Caraça R, Mendes AM, (2009) Freshwater Biology (2009) 54,

28 Restoration scenarios Habitat suitability curves (HSC) target species Iberian nase Iberochondrostoma almacai Iberian chub Squalius aradensis juveniles and adults Weighted usable area (WUA) quantity of area suitable for habitat depth, velocity and substrate suitability indexes. 5 potential habitat enhancement scenarios River 2D Discharge values m 3 /s, range of the ecological flow regime to be released by the dam Boavida I, Santos JM, Lourenço J, Cortes R, Ferreira MT, Pinheiro A, (2008). 4 th ECRR Conference on River Restoration Italy.

29 River channel meandering with submerged weirs River channel meandering + two islands in the mid-section of the channel Manipulation of habitat heterogeneity alone is usually insufficient for restoring biodiversity* Larger scale intervention is usually necessary Introduction of 3 islands into channel midsection changes in land use maintaining or improving riparian vegetation ecological flow regime requirements *Palmer M, Menninger H & Bernhardt E (2010), Freshwater Biology 55 (Suppl. 1), Introduction of two lateral bays on opposite banks Introduction of four alternate triangular deflectors Boavida I, Santos JM, Lourenço J, Cortes R, Ferreira MT, Pinheiro A, (2008) Proceedings of the 4 th ECRR Conference on River Restoration Italy.

30 But.. Manipulation of habitat heterogeneity alone is usually insufficient for restoring biodiversity* Larger scale intervention is usually necessary changes in land use maintaining or improving riparian vegetation ecological flow regime requirements *Palmer M, Menninger H & Bernhardt E (2010), Freshwater Biology 55 (Suppl. 1),

31 The importance of spatial scale Distribution of partitioned variation over the spatial scales of habitat, reach and basin in the Odelouca macroinvertebrate data Hughes, SJ, Ferreira MT Cortes RV (2008). Aquatic Conservation: marine and freshwater ecosystems 18: Hughes, SJ, Santos JM, Ferreira MT, Mendes, A (in press) Environmental Management

32 The next step.. Project RICOVER & collaborative actions INTERREG SUDOE contracts Pilot projects on the Odelouca Bio-engineering Bankside and channel intervention Eradication of invasive plants Acacia and Arundo donax Propagation and planting of native species

33 RHS pros and cons Obvious importance of RHS in a study like this especially at reach scale Limitations Micro-scale habitat features are not included Fluvial geomorphology processes not included Large rivers Transitional waters Limits to analysis