Type-Specific Reference Conditions for Macroalgae and Angiosperms in Scottish Transitional and Coastal Waters
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TYPE-SPECIFIC REFERENCE CONDITIONS FOR MACROALGAE AND ANGIOSPERMS IN SCOTTISH TRANSITIONAL AND COASTAL WATERS FINAL REPORT - 2003 SEPA PROJECT REFERENCE 230/4136 Report prepared by Dr Martin Wilkinson and Paul Wood Report submitted by: Dr Martin Wilkinson Centre for Marine Biodiversity and Biotechnology School of Life Sciences Heriot-Watt University Riccarton Edinburgh EH14 4AS Tel: 0131 451 3468 Fax: 0131 451 3009 e-mail: [email protected] This report was produced by the School of Life Sciences of Heriot-Watt University for the Scottish Environment Protection Agency and is copyright of the Scottish Environment Protection Agency TABLE OF CONTENTS Executive Summary List of Tables, Figures and Appendices 1. Introduction 2. The rocky seashore and the distribution patterns of its organisms 3. The typology used in this report 4. Reference conditions for coastal seaweeds 4.1 Littoral Seaweeds 4.1.1 Introduction 4.1.2 Problems with suggested seaweed features in the Directive 4.1.2.1 Scientific problems 4.1.2.2 Practical problems 4.1.3 Approaches for investigation 4.1.3.1 Biotopes 4.1.3.2 Species richness 4.1.3.3 R:B ratio and other species ratios 4.1.3.4 Functional groups 4.1.3.5 Ecological Status Groups 4.1.4 Methods and results 4.1.4.1 Biotope 4.1.4.2 The seaweed database for estimation of species richness, species ratios, functional groups and ecological status groups 4.1.4.3 Geographic variation 4.1.4.4 Shore types 4.1.4.5 Species richness and ratios from the Scottish shores (a) Species richness (b) Functional groups (c) Ecological Status Groups (d) So what numerical reference conditions can be applied to open coast rocky intertidal seashores based on seaweeds? 4.2 Sublittoral seaweeds 4.2.1 Introduction 4.2.2 Kelp species and depth distribution 4.2.3 Sublittoral seaweed species 4.2.4 Conclusions about sublittoral seaweed reference conditions. 5. Reference conditions for attached algae in transitional waters 5.1 Introduction 5.1.2 Macroalgae of estuaries and their distributions 5.1.3 Can estuaries be categorised on the basis of their attached algae? 5.1.4 The robust nature of attached algae in estuaries 5.1.5 Types of change in estuarine algal communities 5.1.6 Stability of estuarine algae in relation to the definition of reference conditions 5.1.7 Relationship to the Draft Typology for Estuaries 5.2 Sealochs 5.2.1 Introduction 5.2.2 Seaweeds of sealochs 5.2.2.1 Intertidal exposed shores around the loch entrance 5.2.2.2 Sheltered intertidal shores inside the loch 5.2.2.3 The sublittoral zone 5.2.3 How to define reference conditions 6. Marine angiosperms 6.1 What are the marine angiosperms to be considered? 6.2 The species of seagrass in Britain 6.3 The localities where they occur 6.4 Physical habitat preference. 6.5 Reproduction, dispersal and life-cycle 6.6 Ecological importance of seagrasses 6.7 Vunerability of seagrass communities 6.8 Use of seagrasses to define reference conditions 7. Discussion - Type specific reference conditions using marine macrophytes 7.1 Introduction 7.2 Typology 7.3 Intertidal rocky seashores 7.4 Sublittoral rocky seashores 7.5 Transitional waters – estuaries 7.6 Transitional waters- sealochs 7.7 Seagrasses 7.8 Summary of recommendations for further work References cited Appendices List of Tables, Figures and Appendices Tables Table 4.1. The occurrence of characterising species of the sub-biotope MLR.Fser.R in each of 24 sites sampled in Orkney, Central Scotland and Guernsey. Table 4.2. The occurrence of characterising species of the sub-biotope MLR.Fser.Fser in each of eight sites sampled in Orkney Table 4.3. Numbers of species found in Fucus serratus zone on each shore in two different sub- biotopes Table 4.4 The sources of data used to compile a database of seaweed species on a variety of shores around Scotland (and Northern Ireland), mostly from single occasion sampling, selected for the comparability of sampling effort and taxonomic expertise. Table 4.5. The sites included in the references given in Table 4.4 together with their location, species total, habitat type, typology and analyses for which they were used. Gaps in the numbering sequence for shores do not indicate accidental omissions but shores excluded as they had few or no seaweed records. Table 4.6. Summary of results of ordination of collection sites based on seaweed species presence and absence data. Table 4.7. The average seaweed species richness on different physical shore types in Northern Ireland (from Wells & Wilkinson (2002)). The shore types in italics were not used in statistical comparison because of sample sizes below 10. Table 4.8. Mean numbers of intertidal seaweed species recorded on shores with different numbers of prominent subhabitats in Northern Ireland (from Wells & Wilkinson 2002). Table 4.9. Mean numbers of intertidal seaweed species recorded on shores with different degrees of wave exposure, as computed from physical criteria, in Northern Ireland (from Wells & Wilkinson 2002). Table 4.10. The average algal and animal species richness on sheltered and exposed shores as classified by the presence of the indicator species Ascophyllum nodosum and Alaria esculenta respectively in Northern Ireland (from Wells & Wilkinson (2002). (standard deviations shown in brackets). Table 4.11. mean numbers of seaweed species recorded on algal-dominated and non-algal- dominated shores in Northern Ireland, further divided into exposed and sheltered shores on the basis of the presence of Alaria and Ascophyllum respectively. (from Wells & Wilkinson (2002). Table 4.12 Totals of seaweed species found on 35 intertidal rocky seashores sampled during field meetings of the British Phycological Society, 1969-78, with comparable sampling effort and taxonomic expertise (5 shores in Co. Wexford, Eire (Norton 1970); 5 shores in Lewis and Harris (Norton 1972); 6 shores in Galloway (Wilkinson 1980); 4 shores in Glamorgan (Wilkinson 1982); 4 shores in Orkney (Wilkinson 1975); 5 shores in Grampian (Wilkinson 1979); 6 shores in Berwick and East Lothian (Norton 1976)). Table 4.13. Mean numbers of intertidal seaweed species found on 122 shores around the Northern Ireland coastline (from Wells & Wilkinson (2002)) Table 4.14. Totals of intertidal seaweed species found at three sites in Orkney during the British Phycological Society field meeting in 1973 and during a subsequent survey during the same season in 1998 (from Wells, Wilkinson, Tittley & Scanlan- in press). Table 4.15. Seaweed species numbers from 91 shores in Scotland and Northumberland, presumed to be open coastal as explained in the text. Table 4.16. Open coast sites in Scotland and Northumberland arranged in order of species richness Table 4.17. Summary of means and ranges of values of the species numbers, species ratios, functional group and ecological status group composition of shores by type and ecoregion for typology phase 2. Table 4.18. Summary of means and ranges of values of the species numbers, species ratios, functional group and ecological status group composition of shores by type and ecoregion for typology phase 3. Table 4.19. Summary of results from statistical tests of significance of the difference between means of the various numerical indicators calculated from the seaweed species presence at the 68 sites remaining in the database after deletion of estuarine, salt marsh, sea loch and obviously incomplete datasets and sites in Shetland and Northumberland. Results are from one-way analysis of variance, except where data failed a test of normality (indicated by *), then the Kruskal-Wallis non-parametric rank test was used. Table 4.20. The species recorded from shores in Scotland and Northumberland, in Appendix 3, arranged in descending order of the number of shores on which each species is recorded Table 4.21 The percentage of species within each functional form group for 5 different geographic regions (from Littler et al (1983)). Table 4.22. Functional groups and characteristics used by Wells (2002) adapted from Littler et al (1983) Table 4.23. The allocation to functional groups and ecological status groups of species from Scotland and Northumberland in Appendix 3. Table 4.24. The Greek system of classification of shores based on the composition by percentage abundance of seaweed communities of two Ecological Status Groups. Table 4.25 Selected values of the maximum depth of kelp penetration at various locations around the Scottish coast in relation to the draft typology. These values are not necessarily always the lower limit of the kelp forest, but of the plants themselves. Co Durham is included to give a comparison with a turbid, polluted area. Table 5.1 The allocation of Scottish estuaries to groups in the draft typology report (SNIFFER 2003). Estuaries marked with an asterisk (*) are English ones located close to Scotland and have been included because we hold data on the algal distributions within them. The English ones have not been included in the Scottish total in each box in the table. Table 6.1 The Swedish system of classification for eelgrass (Zostera marina) beds on soft bottoms in the Skaggerak/Kattegat Figures Figure 4.1 Ordination by PCA of the full list of sites in Scotland and Northern Ireland based on seaweed species presence/absence data. Figure 4.2 Ordination by PCA of the full list of sites in Scotland based on seaweed species presence/absence data. Figure 4.3 Ordination by PCA of the sites in Scotland, with the deletion of estuarine and saltmarsh sites and those with clearly incomplete lists, based on seaweed species presence/absence data. Figure 4.4 Ordination by PCA of the sites in Scotland, with the deletion of estuarine and saltmarsh sites and those with clearly incomplete lists, and those with less than 40 species, based on seaweed species presence/absence data.