Killer shimps

Dikerogammarus villosus (Sowinsky, 1894) as it is properly known, has now officially spread from the recent 4 known sites including Grafham Water and is now in Pitsford Reservoir. Not that I didn't believe it but as I am the Aquatic Invertebrate recorder for the site I decided to find out for myself.

It likes hard structures so I guessed that the rocky storm defences off the Cliffs would be a safe bet and sure enough they were. Every rock I turned over there were 10/20/30 all shuffling around to get hidden again. I was extremely surprised how settled the colony was with youngsters, juveniles and fully formed adults. I would expect that they have been in there for at least a year or two before now. There is no telling how it got there as it could easily be Fishermen, Sailing boats or even the contractors that built the storm defences as all have associations with Grafham. However as climate change affects us it is not surprising to see our conditions suiting more European species and gradually heading northwards across the country. It will have to be a fact of life that we get used to it as I imagine it will be almost impossible to get rid of them once here it. At Grafham there is some research to say that no longer are there any dragonfly's or damselfly's in the area where the they have colonised. Also under tests they have proven that they will eat or at least shred any invertebrates. I hear fishermen say it will be good food for the fish which maybe the case in the short term but I hope it is not at a cost of all the damsels, sedges and top of the water flies . As it is nocturnal maybe the fish will start feeding at night and create nocturnal fishermen? The environment agency are keen now to understand it's spread up stream in rivers so we will embark on a monitoring programme with AWA to see how it spreads. I would recommend everyone check for these and operate the clean and dry procedures so we can at least slow down the spread.