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Zebra Mussel - Dreissena polymorpha

Habitat:
The Zebra Mussel is found in marine habitats around Ireland. First documented in Ireland in 1997, the Zebra Mussel is now well established in the Shannon, Boyle and Erne water habitats and has spread to over 50 lakes throughout Ireland.

Status:
Dreissena polymorpha is seen in many northern and western freshwater systems in Ireland.

What does it look like?
The Zebra Mussel has a distinctive striped shell and individuals are small, growing up to 3-4 cm in length. They typically live for two to three years. They will settle on a wide range of surfaces including rocks, anchors, boat hulls, intake pipes, other species of mussels and plants.

Impact:
The Zebra Mussel is an invasive species that has altered native ecosystems, which contain economically important or protected species. Zebra Mussels can change nutrient cycles, filter out phytoplankton that form the basis of the food chain, and increase plant growth around lake margins. They can reduce the amount of zooplankton in water, which is important for fish life and can also reduce the population of native mussel species.

As well as threatening native species and ecosystems, the Zebra Mussel can block water intake pipes and boat motors.

Where is it originally from?
The Zebra Mussel spread from the Caspian Sea into Europe in the 17th century and was first documented in Ireland in 1997. It is assumed that it was transported into the country on boats from Britain.

What can you do?
Do not transport the Zebra Mussel to another location. Visit the Invasive Species Ireland website to find out more and to report sitings.

©2007 Department of the Environment, Heritage and Local Government