Objectives
Red list aquatic invertebrates to:
Improve knowledge of
Faunal composition
Habitat association
Change over time
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
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
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%
Measuring change
Data from early twentieth century compared with recent data to determine change in status
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
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!
Siltation - river gravels/lakeshores
Also here: Enicocerus exsculptus, Bidessus minutissimus, Hygrotus novemlineatus (? diffuse pollution)
Drainage - brackish habitats - lagoons
Also here: Ochthebius marinus, Haliplus apicalis, Helophorus fulgidicollis, Enochrus halophilus
Warming - montane sites and species
Also here: Dytiscus lapponicus. Stictotarsus multilineatus, Agabus arcticus
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%
Regional extinction risk
A – past, present or future population declineB – restricted range, fragmentation, continuing declineC – small population size and continuing declineD – very small populations in decline
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
Eutrophication/diffuse pollutionMyxas 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
Drainage and Eutrophication
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
Pre-1980 Post-1980
Drainage – freshwater marshes, floodplains
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
Pre-1980 Post-1980
Drainage - brackish habitats - lagoons
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
Pre-1980 Post-1980
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.
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
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