Discovery of the Asian Clam, (Corbicula fluminea) in Ireland.
Figure 1: Asian Clams in the Barrow (measuring between 1.1 and 1.5cm)
The presence of an established population of the invasive Asian clam at St. Mullins on the River Barrow was confirmed following reports made to the CFB and the CAISIE project team. The team responded by carrying out a scientific survey in the area to investigate the extent of invasion.
The Asian clam (Corbicula fluminea) is an invasive bivalve species that has spread rapidly in lakes, canals, streams, rivers and reservoirs throughout Europe & North America. The species is known to aggressively outcompete native invertebrate communities, limit phytoplankton biomass through intensive water and sediment filtration, colonise water intake pipes, alter benthic habitats/sediments, add biologically available nitrogen and phosphorus to systems, and impact aesthetic and recreational values of the habitats they invade.
Figure 2: Scuba dive survey work being undertaken in the Barrow
The Asian clam was first detected in the Ireland in April 2020 by Dr. Pascal Sweeney within the Barrow Navigation. Preliminary dive surveys were undertaken by the CAISIE project to determine the current distribution and relative abundance. Results indicated that up to 420 individuals per m2, ranging in length from 1.1 to 2.4cm, were present at St. Mullins.
Further surveys are now planned to map the distribution of this species and monitor the impacts to native species. Of particular concern are the potential impacts to some of the protected native species which are currently found in or near the Barrow Catchment (e.g. the pearl mussel, Margaritifera margaritifera and the Twaite Shad, Alosa fallax).
Figure 3: Kick sampling sediments for Asian clams.
The Asian clam population is likely to cause increasing problems throughout the country; many invasive species can travel between and along waterways by various human related distribution pathways (e.g. within the mud on anchors or intentionally as a food source or as live bait). Also, as they are capable of self-fertilisation and can release more than 100,000 juveniles in a lifetime, populations are capable of very rapid expansion. Without strict adherence to biosecurity measures by anyone visiting and moving through the Barrow system, the clam will spread rapidly within this and other catchments.
More information on this species will be available in the near future as research continues. If you have seen any of these clams on other Irish waterways, please contact the CFB immediately (Please email project team on: ).
Figure 4: Abundant clam populations found
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