Image courtesy of the US Army Corps of Engineers Environmental Laboratory
When the eastern gray squirrel was introduced to the UK during the 19th and 20th centuries, it quickly found a niche—outpacing the smaller, weaker, and generally less fit native red squirrel throughout England. Since then, conservationists have struggled to preserve the waning populations of red squirrel and the eastern gray has become a symbol of the dangers of invasive species.
Now, an alien shrimp has appeared in the coastal waters of the UK and experts fear the arrival may be the aquatic equivalent of the gray squirrel introduction.The shrimp, Dikerogammarus villosus, better known as "killer shrimp," is a versatile predator native to freshwater habitats in Eastern Europe. However, it's ability to tolerate a wide range of temperatures, levels of salinity, and oxygen concentrations has allowed it to spread quickly throughout Western Europe.
Once established, the killer shrimp hunts voraciously, often killing other crustaceans and small fish without even eating them. As a result, the shrimp has had a significant impact on freshwater ecosystems from Germany to France to the Netherlands and now, the coast of England.
Paul Leinster, chief executive of the UK's Environment Agency, commented:
We are devastated that this shrimp has been found in Britain...we are currently establishing the degree of the problem, and whether the shrimp is only in Grafham Water or if it is in nearby lakes and the Great Ouse as well.
The silver lining is that Dikerogammarus villosus has been known to eradicate other problematic invasive species—unfortunately, this "service" typically comes at a high cost to natives.