Zebra Mussels, which have been discovered for the first time in Irish fresh waters, can inflict widespread environmental damage on hundreds of important ecosystems, the ESB has warned. The Shannon catchment is especially vulnerable.
The warning came with the publication yesterday of a report by UCG's department of zoology which confirms the mussels' occurrence on the Shannon and their rapid proliferation. They are regarded as "fouling organisms" and usually occur in high density, upsetting the species make-up of water.
Scientists working on a conservation project last summer discovered their presence in Lough Derg and lower reaches of the river. They appear to be spreading to the upper Shannon.
Dr Kieran McCarthy, who compiled the report, said it was likely that the species will "rapidly spread to other inland waterways through river systems and canals".
They are capable of dramatically altering ecosystems by causing changes in algal communities, zooplankton and bottom-dwelling organisms. "Their damaging effects on rare and endangered native species, and potential impact on fisheries conservation are among issues that will have to be monitored," he said.
Zebra mussels are often deceptive. They may contribute to short-term improvements in water quality/clarity. "However, improvements will be more apparent than real and it will be still necessary to concentrate on reducing phosphorous levels in rivers discharging into Ireland's lakes."
Zebra mussels were restricted to the Black and Caspian Seas until the 19th century. They have been in Britain since 1824. In 1985, they were introduced to North America, where their spread caused great concern.
The report says there is no clear indication of how they reached Ireland. They may have come via a ship ballast to Limerick docks or attached to a hull.
The ESB said a research initiative with a view to containing the spread should be pursued urgently.
