WORKSHEET 4

Canal Restoration and the Environment

Zebra mussels are small shellfish, which live in freshwater and feed by filtering the surrounding water and removing the plankton from it. They were formerly found only in the Black and Caspian Seas but expanded their range to include much of Europe following the building of canals by attaching to the hulls of ships and boats. The Zebra Mussel reached Britain in 1830. In 1986 they were introduced to North America in ships' ballast water and now cause serious fouling problems there.

• Find the Black Sea and Caspian Sea in your atlas.
• Why are Zebra Mussels a problem?

Zebra mussels congregatein very large numbers: as many as 100,000 per square metre. They can clog intake pipes, drains and screens causing reduced water delivery to power plants, industries, fish hatcheries and municipal waterworks. They can also have serious consequences for fisheries, fish spawning grounds and aquatic plant life.

Large numbers of zebra mussels were discovered in 1997 in the Republic of Ireland. They probably arrived in Ireland on the hulls of private boats and barges imported on trailers. Every year their numbers increase 50 fold. They are now in Lower Lough Erne. So far no zebra mussels have been found in Lough Neagh but it is only a matter of time before they are introduced to the Lough by accident on the hull of a boat transported by trailer.

• Can you think of any ways in which we might prevent the spread of zebra mussels into Lough Neagh and other inland freshwater navigations in Northern Ireland?
• Look at your map and think about what would happen if the Ulster Canal was restored and boats could once more make the journey from Limerick right up into Lough Neagh.

Write a letter or article for your local newspaper setting out your worries.
 

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