Biological recording and the drivers of change in freshwater

1. Biological recording and the drivers of change in freshwater Roy Anderson

2. Objectives • Red list aquatic invertebrates to: • Improve knowledge of • Faunal composition • Habitat association • Change over time

3. Strategy • Mapping schemes • Require some public participation • Guided by a body of dedicated people driving and co-ordinating/validating • Ideally with regular updates via websites • Eventually, publication of atlases

4. Outcome • Mapping schemes Red Lists • The Red Listing process should: • Obtain and encode all historical data • Compare with modern results • Be subject to periodic update as new data becomes available • Classify fauna according to IUCN guidelines and register level of threat • Draw in available habitat, climate and water quality data to compare with faunal distribution and relate to perceived changes in that distribution

5. Adephaga

6. Aquatic and semi-aquatic Adephaga • Red List published in 2009 • 244 taxa recorded belonging to 16 families, both fully aquatic and marginal; 73 red-listed i.e. 30%

7. Measuring change • Data from early twentieth century compared with recent data to determine change in status

8. Regional extinction risk A – past, present or future population decline B – restricted range, fragmentation, continuing decline C – small population size and continuing decline D – very small populations in decline

9. Evaluation • Only a small minority of the declining species were considered to be in a general population decline i.e. a decline across the country by comparing distribution pre and post 1980 (category A2) • The vast majority of highly threatened species were considered a priori to have fragmented ranges or specific requirements (stenotopy) which was related to decline (category B2) • A large number placed in a lower threat category (VU) were considered at risk because of the small population size or limited number of available sites (category D2) • A similar number were also classed as near threatened (category A3) because of more general decline, but related to reliance on a specific habitat • Many species associated with fen habitats showed little real evidence of decline but were classified as at high risk because of findings outside Ireland • The habitat with most at risk species was fen (next slide) but few fen species actually show a decline in Ireland!

10. Habitat associated decline

11. Siltation - river gravels/lakeshores Also here: Enicocerus exsculptus, Bidessus minutissimus, Hygrotus novemlineatus (? diffuse pollution)

12. Drainage - brackish habitats - lagoons Also here: Ochthebius marinus, Haliplus apicalis, Helophorus fulgidicollis, Enochrus halophilus

13. Warming - montane sites and species Also here: Dytiscus lapponicus. Stictotarsus multilineatus, Agabus arcticus

14. Mollusca

15. Measuring change • Red List published in 2009 • 150 total native spp of which 53 are red-listed: i.e. 35% • 79 aquatic of which 31 are red-listed i.e. 39%

16. Regional extinction risk A – past, present or future population decline B – restricted range, fragmentation, continuing decline C – small population size and continuing decline D – very small populations in decline

17. Evaluation • Very different from Adephaga • Risk seems to have its greatest concentration in category A suggesting general decline rather than association with rare habitats (stenotopy) or having a previously fragmented range • This suggests that an important environmental variable has changed recently and is affecting many species

18. Examples

19. Eutrophication/diffuse pollution Myxas glutinosa Glutinous snail IUCN Endangered A2c A declining species across its entire west palaearctic range. Ireland is now its headquarters with up to 50% of global population. Needs gently flowing, low-P calcareous waters. Also here: Omphiscola glabra, Anisus vortex, Radix auricularia, Margaritifera margaritifera, Pisidium lilljeborgii, P. pulchellum, P. moitessierianum Pre-1980 Post-1980

20. Drainage and Eutrophication Pre-1980 Post-1980 Omphiscola glabra Mud snail [IUCN Extinct ] – Critically endangered A declining species across most of Europe. Confined to the south-east, and recently re-discovered at a site in Co Waterford. Requires low-P poor fen or undrained low-nutrient riverine marshes

21. Drainage – freshwater marshes, floodplains Pre-1980 Post-1980 Aplexa hypnorum Moss bladder snail IUCN Vulnerable A2c Widespread Palaearctic species living in temporary habitats, especially on winter-flooding lakeshores and riverbanks. Declining thro’ habitat destruction Also here: Quickella arenaria, Succinella oblonga, Vertigo antivertigo, V. moulinsiana, Musculium lacustre, Sphaerium nucleus

22. Drainage - brackish habitats - lagoons Pre-1980 Post-1980 Hydrobia acuta neglecta Hydrobiid snail IUCN Endangered B2a,b(iii,iv) A north European endemic. Confined to coastal lagoons of high salinity. Four known sites, two of which have recently been destroyed by drainage/changes in management. Also here: Ventrosia ventrosa, Truncatella subcylindrica, Mercuria cf. similis

23. Warming - montane sites and species Pisidium conventus Arctic-alpine pea mussel IUCN Critically Endangered B2ab(i,ii,iii,iv) Boreal relict, probably in steep decline. Only one recent site.

24. Conclusions

25. Drivers of change • Both Coleoptera and molluscs suffer from diffuse pollution via its effects on algal growth, de-oxygenation etc. • This reaction appears more restrained in Coleoptera which are threatened more by range fragmentation and destruction of specific fen and peatland types • Molluscs are possibly unable to escape the effects of diffuse pollution because they and are less mobile and have a more permeable integument • May be good indicators of pollution, both point source & diffuse • Beetles may be more useful in assessing the decline of specific habitats • Brackish habitats home to both groups continue to decline and pose a threat to many stenotopic species • Warming affects only one mollusc but a number of beetles