Quagga Mussel (Dreissena bugensis)

Quagga mussels are a sessile bivalve typically less than 5cm in length and triangular in shape. They have alternating light and dark brown stripes, but can also be solid brown. In lakes, rivers and estuarine habitats, quagga mussels effectively filter plankton out of the water, outcompete native mussel species and depleting plankton as a food source for native species. A mature female mussel can produce up to one million eggs/year, having a significant impact on freshwater ecosystems. Additionally, quagga mussels can affect water quality and clog water pipes.

Larvae can drift downstream for 3-4 weeks and up to 300km before attaching to substrate and forming new populations. However, humans are typically responsible for most introductions to new places via fish wells and parts of boat motors. In temperate summer conditions, adult mussels can survive on overland transport for up to 5 days.

In Ireland, quagga mussels were first observed in Shannon’s Ree and Derg lakes in 2021 as well as the river between these lakes.

• Avoid stepping into the water – this can stir up sediment, throwing up sediment DNA and any inhibitory molecules present. Sediment may clog the filter and prevent sufficient volumes of water being filtered.
• Any suspected sightings or positive eDNA results should be reported to the relevant monitoring programme. Ireland: Records Biodiversity.