Environment Agency ecologists have found a population of Quagga mussel in a tributary of the River Colne in the Thames catchment near Staines. This record was confirmed by Dr David Aldridge of Cambridge University on the 1st October 2014. Further investigation has revealed that a population of these alien mussels have now also established themselves in Wraysbury reservoir.
The Quagga mussel (Dreissena rostriformis bugensis) is a highly invasive non-native species, which has been expected to arrive in the UK for a number of years. Similar to another alien mussel - the now widespread Zebra mussel - this species comes from the Ponto-Caspian region (an area around the Black and Caspian seas).
Due to its filtering capacity and ability to produce dense populations, it can significantly reduce native biodiversity, and alter whole freshwater ecosystems. It is expected to occupy similar habitats to the Zebra mussel, but can survive in some places that Zebra mussel can't and can even displace them.
It feeds on the varieties of algae that compete with blue-green algae, often resulting in toxic algal blooms. It can also be a nuisance and economic problem when growing in pipes of water treatment plants, so you can see that its arrival in our UK waters is yet another headache for all those concerned with trying to maintain our aquatic environment.
There is no effective eradication method for Quagga mussel once it has established in a reservoir and the downstream river system. As recommended in a recent review commissioned by Defra of options to deal with the arrival of Quagga mussel, the best method of slowing the spread of the Quagga mussel is by applying better bio-security through the “Check, Clean, Dry” approach, which does what it says – check and wash all of your equipment and clothing and then dry it thoroughly.
Quagga mussels can be hard to distinguish from Zebra mussels, which are already widespread in England and Wales. Quagga mussels are able to colonise freshwater rivers, canals and lakes and are small in size, being quite similar to the Zebra mussel, but lack the strong ridge that gives Zebra mussel its 'D' shape. The Quagga mussel is however, much more rounded and so the best way to identify it is to place it on its front, as it will then roll to one side, unlike the Zebra mussel.
So, to all you fishermen and women in particular out there, do try not to hasten the spread of these 4cm (1.5in) beasties from river to river by carrying out bio-security procedures. I have to say though, if we follow in the steps of America were these little critters were introduced to the Great Lakes by ships discharging their ballast, it does not look at all promising. Both Quagga and Zebra mussels have now spread to 29 states across the USA.
All really rather depressing.