The Killer Shrimp (Dikerogammarus villosus) that is. This invader made it’s first appearance in the UK only a month ago (Sept 3rd ’10) in Cambridgeshire.
Believed to spread by ballast water on water kit; fishing gear, boats, trailers, canoes, kayaks and utensils washed in water bodies.
The Killer Shrimp belongs to the same family as native freshwater shrimp (Gammaride), however, D. Villosus is quite larger than native species in Ireland and the UK and has stronger mouth parts to suit. Giving the alien a clear advantage over food resources. Killer Shrimp will attack and eliminate native gammarus.
The Killer Shrimp has is an insatiable hunter, killing fish as swell as inverts. When introduced into new habitat, it will quickly establish and dominate, forcing native population to crash and will cause substantial ecological damage.
The alien also develop extremal quickly, in spring growth can be as much as 2.6mm in two weeks, becoming sexually mature at 6mm with high fecundity and can sexually reproduce all year.
Like any good invasive species the Killer Shrimp is tolerant to changes in; temperature, salinity and oxygen levels.
This alien has not yet been recorded in Ireland, hopefully it will stay that way. However, with recreational boating and ballast water this species main vector I fear the Killer Shrimp will be making it’s way to Ireland in the not too distant future. Unless preventative action takes place.
Here is some excellent literature and a useful ID for Dikerogammarus villosus the Killer Shrimp!