Zebra mussel

These stripy stowaways landed in Britain’s waterways on the hulls of ships from Eastern Europe and decided to stay.

Zebra mussels in line on rock Zebra mussel, copyright GBNNS

Growing up to 5cm long, these molluscs rapidly form large colonies that attach to almost any submerged hard surface, impeding the smooth running of canal gates and sluices.

Although they increase water clarity by feeding on plankton, this is not a good thing. Clearer water means that sunlight is better able to penetrate the water and stimulate the growth of invasive weeds.

Zebra mussels have also been found to have a detrimental effect on the native swan mussel population, and are responsible for drastically altering the ecology of the waters in which they live by changing fish populations. This happens when zebra mussels take over spawning grounds and change the populations of animals that the fish eat.

They are mostly spread through recreational boating and angling, when the mussels attach themselves to a boat's hull or some equipment and are then transported to other waters.

Last date edited: 17 November 2020