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Water Framework Directive Development of Classification Tools for Ecological Assessment Water Framework Directive Development of Classification Tools for Ecological Assessment: Intertidal Seagrass (Marine Angiosperms) Foden,J., Brazier,P., Best,M., Scanlan,C. & Wells,E. 2010 UKTAG Report: Seagrass v3 Contents 1. Summary .......................................................................................................................... 5 2. Background to the WFD ................................................................................................ 5 3. UK Process of WFD Development ............................................................................... 7 3.1 UK TAG ................................................................................................................... 7 3.2 MPTT ....................................................................................................................... 9 4. Normative definitions & Reference conditions ........................................................... 9 4.1 Expanded Normative Definitions ....................................................................... 11 4.2 Reference Conditions ......................................................................................... 13 4.3 Ecological Quality Status ................................................................................... 14 5. Seagrass Monitoring Tool ............................................................................................ 16 5.1 Introduction ........................................................................................................... 16 5.2 Database............................................................................................................... 17 5.3 Determination of tool components .................................................................... 19 5.3.1 Taxonomic Composition ................................................................................ 20 5.3.2 Abundance Determined by Bed Extent and% cover (Shoot Density) ..... 20 5.4 Development of Metrics ...................................................................................... 22 5.4.1 Taxonomic Composition ................................................................................ 22 5.4.2 Abundance - Bed Extent ................................................................................ 23 5.4.3 Abundance - Shoot Density/Percentage cover .......................................... 25 5.4.4 Ecological Status: Combining the Metrics ................................................... 28 5.5 Application of the Tool ........................................................................................ 29 5.5.1. Preliminary Assessment ............................................................................ 29 5.5.2 General Sampling Considerations ................................................................ 30 5.5.3 Abundance - Bed Extent ................................................................................ 31 5.5.4 Abundance - Shoot Density (% cover)......................................................... 31 1 UKTAG Report: Seagrass v3 5.5.5 Taxonomic Composition ................................................................................ 32 5.6 Data collection ..................................................................................................... 32 5.7 Summary of Classification Process .................................................................. 34 5.8 Worked Examples ............................................................................................... 35 5.8.1 Taxonomic Composition ................................................................................ 35 5.8.2 Abundance - Bed Extent ................................................................................ 36 5.8.2.1 Milford Haven Intertidal Seagrass Beds ............................................. 36 5.8.2.2 Pembrokeshire Intertidal Beds ............................................................. 37 5.8.2.3 Pembrokeshire Subtidal Beds ............................................................. 37 5.8.2.4 North Haven, Skomer Marine Nature Reserve, Pembrokeshire .... 38 5.8.3 Abundance - Shoot Density ........................................................................... 38 5.8.3.1 Milford Haven Intertidal Beds .............................................................. 39 5.8.3.2 North Haven, Skomer, Subtidal Beds ................................................ 39 5.8.3.3 Isles of Scilly Subtidal Seagrass Beds ................................................ 40 5.8.4 Overall Ecological Status; Combining the Metrics ..................................... 43 6. Response to Pressures ................................................................................................ 44 7. Confidence in the assessment .................................................................................... 47 7.1 Confidence in data - Sampling strategy and frequency................................. 47 7.2 Confidence in Data – Quality control ................................................................ 47 7.3 Confidence of Classification .............................................................................. 48 8. European Intercalibration ............................................................................................ 49 8.1 IC Phase One - National Methods Under Intercalibration ............................. 49 8.2.1 Boundary Criteria ............................................................................................ 52 8.2.2 Testing UK Waterbody Data against NL and UK Metrics ......................... 53 8.2.3 Testing Dutch Waterbody Data against NL and UK Metrics .................... 55 9. References ..................................................................................................................... 58 2 UKTAG Report: Seagrass v3 List of Tables Table 1 a) & b): Normative definitions for marine angiosperms in coastal and transitional waters Table 2: Description of the characteristics of seagrass at the High, Good and Moderate WFD status classes in accordance with the normative definitions (WFD Annex V) and expanded normative definitions (detailed national interpretation). Table 3: Metric description and EQRs for taxonomic composition Table 4: Metric system developed for the classification of changes in spatial extent of angiosperm beds Table 5: Metric system developed for the classification of annual changes in angiosperm shoot density/% cover Table 6: Metric system developed for the classification of changes in rolling mean of angiosperm shoot density. Table 7: Overall ecological status boundaries for the intertidal seagrass tool Table 8: Taxonomic composition index tested against a variety of UK coastal (CW) and transitional (TW) water bodies with littoral or sublittoral seagrass beds. Table 9: Percentage cover results for Angle Bay Table 10: Abundance determined by shoot density index, tested against individual Isles of Scilly seagrass beds and as an overall mean for the water body. Density (shoots m-2) reported to 3 sig. figs. Table 11: Overall ecological status of three exemplar UK seagrass beds, calculated from mean scores of assessment metrics. Table 12: Summary of UK and NL seagrass metrics and boundary conditions for ecological status classes (Foden and Brazier, 2007; de Jong, 2004). Table 13: Current situation of seagrass in (a) Strangford Lough (Portig, 2004) and (b) Fleet lagoon (Bunker et al., 2004), and outcomes of testing UK and NL metrics. Table 14: P-REF and PGES for four Dutch water bodies (de Jong, 2004) and the outcomes of testing UK and NL metrics on data for; (a) Wadden Sea, (b) Oosterschelde, (c) Ems- Dollard and (d) Westerschelde. 3 UKTAG Report: Seagrass v3 List of Figures Figure 1: Suggested Ecological Quality Ratio; Annex V, 1.4.1 (From COAST Guidance, Vincent et al., 2002). Figure 2: Distribution of Zostera species in mainland UK (Davison & Hughes, 1998 and Stewart et al., 1994). Figure 3: Seagrass bed locations from the JNCC’s MNCR database. Figure 4: Example recording sheet manual method. Figure 5: Flow chart summarising the main stages involved in undertaking and assessment using the intertidal seagrass tool Figure 6: Angle Bay inter-tidal seagrass bed B. Figure 7: North Haven Zostera marina bed area; 1982, 1997 and 2002 areas mapped by divers with high accuracy, 2000 and 2004 areas derived from boat GPS are less accurate (Burton et al., 2005) (raw data unavailable for calculation of error statistics). Figure 8a-e: Annual mean shoot density in five Isles of Scilly sublittoral seagrass beds with standard error bars; (a) Old Grimsby Harbour, (b) Higher Town Bay, (c) Broad Ledge Tresco, (d) West Broad Ledge, and (e) Little Arthur (data from Cook, 2005). Note data only available for 9 and 8 years for West Broad Ledge and Little Arthur, respectively. Figure 9a & b: Shoot density in Isles of Scilly sublittoral seagrass beds; (a) rolling 5- year mean of shoot density of five beds, and (b) annual mean shoot density for all seagrass beds in the Isles of Scilly water body (data from Cook, 2005). Note different time period on x-axes. Figure 10: Mean % leaf cover of Zostera at 7 sites along a transect; Westfield, North Morecambe. Figure 11: Temporal trends in Strangford Lough seagrass % density. 4 UKTAG Report: Seagrass v3 1. Summary This report details the development of the Water Framework Directive (WFD) Intertidal Seagrass tool. The report consists of a general background to the WFD, normative definitions and reference conditions.
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