Factors contributing to the invasive success of Corbicula fluminea
Invasive Characteristics and Control Options for Asian Clam (Corbicula fluminea) in Ireland Dr Joe...
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Transcript of Invasive Characteristics and Control Options for Asian Clam (Corbicula fluminea) in Ireland Dr Joe...
Invasive Characteristics and Control Options for Asian Clam (Corbicula fluminea) in Ireland
Dr Joe Caffrey
Inland Fisheries Ireland
ISI Forum, Belfast Museum – 20th April 2011
Scope
Description and general ecology
Impacts
Distribution and basic metrics
Control options
Corbicula fluminea – Description
Yellow-brown (to black) bivalve
Shell has concentric, evenly-spaced, thick ridges
Usually < 25 mm but can grow to 50 mm in length
Corbicula fluminea – Habitat
Freshwater: lakes, canals, rivers and streams
Common in tidal sections of large rivers but …..
Intolerant of pollution
Intolerant of low dissolved oxygen conditions
Tolerant of low salinity brackish water (5 – 8 ppt)
Sand and small gravel habitats, but flexible
Corbicula fluminea – Life Cycle
Hermaphrodite, capable of cross- and self-fertilisation
Reproduce in spring and autumn
Can produce up to 70,000 juveniles per annum
Juveniles fully formed on release, with a single mucilaginous byssal thread
Maturity occurs at 3 – 12 months
Adult life span is variable, spanning 1 – 5 years
Corbicula fluminea – Vectors for Spread
Food item
Angling bait
Aquarium dump
Water craft - bilge water, sediment on anchor, juveniles byssally attached to boat hulls….
In dredged river gravel or soil
Byssal thread attachment to water fowl, floating debris or vegetation
Water movement in natural systems
Corbicula fluminea – Impacts
High density and high filtration rate (up to 1 litre per hour) will alter trophic and nutrient dynamics
Compete with other filter feeders for limited food resources
Compete with other mollusc species by pedal feeding in sediment
Accelerate deposition of organic matter, altering substrate composition
Efficient ecosystem engineer – altering the structure and function of invaded habitats
High filtration capacity will increase water clarity
Corbicula fluminea – Impacts
Macro-fouling of pipes
Efficient ecosystem engineer – altering the structure and function of invaded habitats
Clog gravels and interfere with spawning for salmon and trout
Uproot and displace native mussels (including protected species)
Increase flood hazard as shells accumulate by reducing discharge capacity
blocking sluice gates, pipes… Impact navigation by shallowing channels; increase dredging episodes
Corbicula fluminea – Distribution
Native to southern and eastern Asia, Australia and Africa
Introduced into North America in early 1900s
Now present in 38 States
Introduced to Europe in 1980 – first records in eastern France and Portugal
By 2000 present in most major watersheds on the European mainland
First record in Britain in 1998 (Norfolk Broads) and in River Thames in 2004
Distribution in Ireland 2010 - 2011
First record in River Barrow April 2010, at St Mullin’s
Distribution determined (SCUBA) in Barrow and Nore in June/July 2010
None above tidal reaches
River Suir surveyed in September 2010
Corbicula – Density
Location No./sq m Max. No./sq m
St Mullin’s, Barrow 96.8 + 21 146.8
Scar, Barrow 5,742.6 + 2,409 9,636
Poulmounty, Barrow 964 + 232 1,196
River Nore 320 + 9 336
Corbicula in River Barrow at Scar (d/s St Mullin’s)
2 3 4
Age
10
15
20
25
30
Sh
ell
len
gth
Asian clam – Size & Age Class
Distribution in Ireland 2010 - 2011
Recorded in Carrick-on-Shannon in September 2010
present over 15 km long section
Recorded in Lough Derg in January 2011
Asian clam – Control Options
Determine national distribution and scale of problem
Issue alerts to public and stakeholders
Seek funding
Proposed Action Plan
Asian clam – Control Options
Determine national distribution and scale of problem
Issue alerts to public and stakeholders
Seek funding
Study habits and reactions to toxins in vivo (with QUB)
Suction dredge (poss. use cockle harvester)
Benthic barriers – biodegradable jute / plastic or rubber mats
Benthic barriers and chemical additives (e.g. salt)
Proposed Action Plan
Corbicula is susceptible to anoxia High mortality recorded beneath barriers in Lake Tahoe and Lake
George (USA)
Benthic Barrier Trials in River Barrow 2010/2011
Corbicula is susceptible to anoxia High mortality recorded beneath barriers in Lake Tahoe and Lake
George (USA)
Benthic Barrier Trials in River Barrow 2010/2011
Trials commenced using jute matting and plastic in December on River Barrow
Benthic Barrier Trials in River Barrow 2010/2011
Barriers laid in adverse conditions – cold and flood events
Most barriers were disturbed by tidal flows and floods
Results inconclusive
Will recommence trials in May with QUB
Site visit planned by scientist leading work in Lake George (USA)
Asian clam – Control Options
Determine national distribution and scale of problem
Issue alerts to public and stakeholders
Seek funding and support
Study habits and reactions to stimuli / toxins in vivo
Suction dredge (poss. use cockle harvester)
Benthic barriers – biodegradable jute / plastic or rubber mats
Benthic barriers with chemical additives (e.g. salt)
Biobullet
Proposed Action Plan
Biobullet Treatment
Encapsulates toxins within edible coating, giving efficient and targeted control to Corbicula
Toxin is concentrated by Corbicula as it filter feeds
Anything not ingested degrades to harmless concentrations within 1 hour of entering water
Approved for use in drinking water
Collaboration with Univ of Cambridge to commence in May 2011
Asian clam – Control Options
Determine distribution and scale of problem
Draw up Risk Register
Seek funding and support
Distribute Alerts and create awareness
Study habits and reactions to stimuli in vivo
Suction dredge
Benthic barriers
Benthic barriers with chemical additives (e.g. salt)
Biobullet
Any other ideas
Proposed Action Plan
Will we eradicate Corbicula from Ireland?
Probably not!
but research may enable us to deal with invasions into new and sensitive habitats
Thanks to
NPWS
Heritage Council
IFI SERBD
EU Life+ CAISIE project