EPA funded research maps feral Pacific Oyster populations in Ireland

Date released: Oct 04 2013

EPA-funded research maps feral populations of Pacific Oyster, and concludes that controls on this species would be prudent to reduce potential consequences for native biodiversity. 

The Environmental Protection Agency (EPA) has today released the findings of a research project into the impacts of feral populations of the Pacific oyster on biodiversity and ecosystems services. The project focuses on how their spread can impact on the ability of estuaries to support aquaculture and fisheries.

The Pacific oyster has been extensively cultivated in Ireland since the 1970s, but has not become invasive, unlike in other parts of the world where it has established large populations outside its native range, causing dramatic effects on native ecosystems and the human activities that depend on them.

Dr Tasman Crowe, School of Biological and Environmental Science, UCD, who led this part of the Project said,

“Our research has documented feral populations of the Pacific oyster in parts of Ireland.  Analysis of the current distribution of these populations provides a basis for predicting where it may become established in the future.  Experimental tests show that if it does become more widely established, the Pacific oyster would affect native biodiversity in intertidal habitats, including having negative impacts on the honeycomb worm which constructs reefs which are protected by the EU Habitats Directive. The oysters also alter several biogeochemical properties and processes, potentially reducing the capacity of estuaries to support aquaculture and fisheries.”

Dr Crowe concluded,

“Although wild populations of the Pacific oyster are currently harvested, their commercial value would be greatly reduced if the beds become too dense.  Any attempt to control or reduce their spread should be initiated sooner rather than later.”

The project forms part of a larger project quantifying the impacts of key sectoral activities in Ireland on biodiversity and the ecosystem services they provide, including pollination, biological pest control, carbon sequestration and resistance to alien species invasion.  The report, Sectoral Impacts on Biodiversity and Ecosystems Services: SIMBIOSYS Project Synthesis Report, focuses on the impacts of aquaculture, bioenergy crops, and the landscaping of road corridors.

Dara Lynott, Deputy Director General, EPA, said,

“This research, funded by the EPA’s STRIVE research programme, is essential to assess the impacts of the Pacific oyster on our natural environment and provides solutions for emerging environmental problems.  The project has identified some “win-win” situations where both the quality of Ireland’s ecosystems and socioeconomic outputs can be maximised.”

This collaborative project, led by Jane Stout of Trinity College Dublin, involved partners in University College Dublin, University College Cork and NUI Galway, as well as stakeholders in the National Parks and Wildlife Service, Teagasc, National Roads Authority, the Loughs Agency, Bord Iascaigh Mhara and scientific collaborators in Ireland and overseas.

The full report Sectoral Impacts on Biodiversity and Ecosystems Services: SIMBIOSYS Project Synthesis Report (STRIVE Report no. 115) is available on the EPA website. All papers, reports and theses from the project are available on www.tcd.ie/research/simbiosys

Notes to Editors:

The SIMBIOSYS team has documented feral populations of the Pacific oyster in Loughs Foyle and Swilly and smaller numbers of individual oysters in the Shannon, Galway Bay and Tralee Bay. The species is also established in Strangford Lough. Genetic studies indicated that the Lough Foyle populations have not come from current aquaculture activities but may have escaped from cultivation sometime in the past and now appear to be reproducing independently. 
The report recommends using sterile triploid oysters in aquaculture to reduce the risk of invasion and negative impacts on coastal ecosystems.  This can benefit aquaculture because individual oysters grow more quickly.