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Biological recording and the drivers of change in freshwater. Roy Anderson. Objectives. Red list aquatic invertebrates to: Improve knowledge of Faunal composition Habitat association Change over time. Strategy. Mapping schemes Require some public participation

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Presentation Transcript
objectives
Objectives
  • Red list aquatic invertebrates to:
  • Improve knowledge of
    • Faunal composition
    • Habitat association
    • Change over time
strategy
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
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
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
Measuring change
  • Data from early twentieth century compared with recent data to determine change in status
regional extinction risk
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
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
Siltation - river gravels/lakeshores

Also here: Enicocerus exsculptus, Bidessus minutissimus, Hygrotus novemlineatus (? diffuse pollution)

drainage brackish habitats lagoons
Drainage - brackish habitats - lagoons

Also here: Ochthebius marinus, Haliplus apicalis, Helophorus fulgidicollis, Enochrus halophilus

warming montane sites and species
Warming - montane sites and species

Also here: Dytiscus lapponicus. Stictotarsus multilineatus, Agabus arcticus

measuring change1
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 risk1
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

evaluation1
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 pollution
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

drainage and eutrophication
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

drainage freshwater marshes floodplains
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

drainage brackish habitats lagoons1
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

warming montane sites and species1
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
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