Another Alien Alert - Killer Shrimp in the UK



The predatory shrimp Dikerogammarus villosus

 Another invasive species has hit the headlines in the past weeks, the predatory shrimp Dikerogammarus villosus, which preys on a wide range of macro-invertebrates and even small fish. It comes from the Steppe region between the Black Sea and the Caspian Sea. The shrimp is much larger (up to 30mm) than the native shrimps such as Gammarus and has obvious strips making it easy to identify.  The shrimp, described by the Environment Agency as 'particularly vicious and destructive'  was discovered by anglers in Grafham Water, a large reservoir in Cambridgeshire. It has rapidly been moving throughout Europe mainly via the River Danube, but it was a shock when it turned up in the UK.  A containment strategy has been put into place with the water leaving the  reservoir passing thorough a double set of coarse and fine mesh, although it is inevitable that the species will escape into the adjacent River Ouse.  All boat movements are being closely monitored.  The Environment Agency have moved very quickly to control this invader and it will be interesting if the strategy succeeds. Link

River Danube at Risk

A number of people have emailed me asking about the chemical nature of the sludge and its potential impact.  Little has been posted about the exact composition of the sludge except that it is very alkaline ( up to pH 13) and contains heavy metals including cadmium and chromium although in low concentrations.  These wastes are also generally rich in fluoride, sulphate and of course aluminate, but other metals such as nickel, manganese, lead arsenic etc. are also present.  Of course it is also rich in ferric oxide which gives the sludge its distinctive red colouration. The sludge now has entered the Danube which is 2,850 kilometers long and so provides a huge potential dilution for the pollution.  Croatia, Serbia and Romania have all begun testing the river every few hours with high pH values initially reported (pH 9-10) making ammonia a critical problem as it shifts into its unionized form.  Key impacts are suspected to be sedimentation of the solids, ammonia and aluminum toxicity (until pH neutralizes) and possible metal interactions.