Beware the Quagga

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In October 2014 quagga mussel was found in Wraysbury Reservoir and the Wraysbury River, a tributary of the River Colne, near Egham, Surrey, and subsequently in a number of other waterbodies. This is the first UK record of this species.

The quagga mussel (Dreissena rostriformis bugensis) is a highly invasive non-native freshwater mussel from the Ponto-Caspian region. It can significantly alter whole ecosystems by filtering out large quantities of nutrients and is also a serious biofouling risk blocking pipes smothering boat hulls and other structures.

Quagga mussels can be hard to distinguish from zebra mussels, which are widespread in England and Wales. They are able to colonise freshwater rivers, canals and lakes. They are small in size (similar to zebra mussel) but lack the strong ridge that gives zebra mussel its 'D' shape. Quagga mussel is more rounded and so when placed on its front it will roll to one side, unlike the zebra mussel. More information on the quagga mussel and its identification is available from the species alert pages of the Non-native Species Secretariat.

If you spot a quagga mussel, you must report it: Send a photograph along with details of the sighting to: email or report it online.

There is no effective eradication method for quagga mussel once it has established in a reservoir and the downstream river system. Defra advise the best method of slowing the spread of the quagga mussel is by applying better biosecurity through the Check, Clean, Dry approach. 

The larvae of quagga mussel (veligers) are not visible to the naked eye which makes drying a critical step in applying good biosecurity. There's good evidence that rinsing or soaking in hot water improves the chances of killing larvae and adults, and is a suggested addition to the Check, Clean, Dry approach.  

All users of IBRSC must take note of and implement the detailed guidance below:

 All equipment that has been in contact with the water should be thoroughly 
checked, cleaned and dried before moving off site. 
 Equipment should be checked for the presence of adult mussels which 
should be removed and disposed of safely, away from uninfected water 
bodies.
 Equipment should be thoroughly cleaned. If facilities allow, equipment should 
be subjected to immersion in hot water (at least 45 degrees Celsius) for 15 
mins. The washings should be contained and not allowed to enter any 
watercourse or uncontained drainage system. Larger objects can be cleaned 
using a hot pressure wash at least 45 degrees Celsius for one minute per 
area under the jet.
 Equipment should be dry for 48 hours before it is used elsewhere. Drying is 
not very effective against adult quagga mussel, but is expected to be effective 
against the larval stages. 

Check, Clean, Dry is important not only to help slow the spread of this species, but also other invasive species that might be present in our waterways. It is especially important to prevent the spread of invasive non-native species to isolated locations (not connected to other water bodies) and protected areas such as SSSIs. Any structures or equipment such as jetties or boats which have been submerged in water for a time, pose a higher risk of spreading invasive species and so extra care should be taken when moving or working with them.