Most Unwanted: Quagga mussel
Dreissena bugensis
Habitat: Freshwater
Threat: Fouling, negative impacts on native species and local extinction of unionids
Status: Potential
This species is very similar to the already established Zebra mussel. In the US, quagga mussels have been found to out-compete the zebra mussel for space and resources, while being able to colonise deeper waters. This species poses a significant threat to freshwater ecosystems in Ireland.
What is it?
Zebra mussel and the quagga mussel are very similar in their appearance. They can sometimes be differentiated by the shape of the shells. However, expert knowledge is needed to distinguish these two species.
Impact
Like the zebra mussel, the quagga mussel increases water clarity and decreases phytoplankton abundance. Quagga mussels also cause a reduction in zooplankton populations. Native species of Unionids can suffer as a result of the introduction of both zebra and quagga mussel.
This species is also an economic pest acting as a fouling organism and increasing the cost of water treatment and the cost to industries dependent on freshwater e.g. hydroelectric power stations.
Where are they from?
Ponto-Caspian region (Black, Caspian, Azov Seas)
Where are they now?
Currently invasive in North America where significant and costly efforts are in place to reduce spread and impact. Also spreading within continental Europe.
How can they get here?
Fouling of boats and other machinery.
Ballast water.
What you can do
Ensure all boats and machinery that has been in an infected waterbody has been properly cleaned.
Never allow material from one waterbody to enter another.
Report all sightings.
