Pernicious threat of zebra mussels crossing Border

It is pernicious, pestilent, noxious and even cross-Border bodies with full executive powers will not halt the zebra mussel, an international workshop has concluded in Galway.

Hitherto confined to the Republic's inland waterways, where it has the potential to cause serious economic damage, the pest has been discovered on Lough Erne in the last few weeks. Dr Kieran McCarthy, a freshwater ecology specialist at NUI Galway's zoology department, has called for immediate implementation of a monitoring and research programme to investigate the biology of the zebra mussel (Dreissena polymorpha) under Irish conditions. International experience of the fouling organism, indicates it could cost the State millions of pounds, due to the potential clogging of pipes, submerged structures and industrial equipment.

Water abstraction for domestic and industrial use may also be affected by the tiny striped mollusc. Such is its resilience and the potential risk that some 100 US and European scientists came to Furbo, Co Galway, this week for a three-day workshop sponsored by the ESB and the US Sea Grant programme.

Dr Charles O'Neill of New York Sea Grant said there was no "silver bullet" for controlling the pest, which has been found in populations of up to 750,000 per square meter in some Great Lakes facilities. A single layer of 12 mm mussels throughout a pipeline can decrease the conduit's efficiency by 510 per cent as a result of increased friction. Chemical treatment may not be the answer, Mr Tim Bowmer of the Dutch Department of Environmental Toxicology said yesterday. Some biocides may be subject to new EU restrictions, and this type of treatment may only cause greater ecological damage than the mussel itself, he said.

The mussel can indicate pollution in a waterway, due to its tolerance to toxic substances. How ever, other biological methods, such as the use of trout in tanks, are less lethal and pose less risk to the food chain and fisheries.

Zebra mussels are native to the Black and Caspian sea regions, and began to spread throughout European waterways in the last century as new canals were built. They are believed to have spread to Ireland some two to three years ago, possibly on the bottom of an imported barge. They were discovered in large numbers on the lower river Shannon and Lough Derg in 1997. The female produces more than a million eggs in her short two to three-year lifespan. A handful of mussels can quickly colonise a lake system and can clog up pipes in no time.