The widespread and abundant killer shrimp (6) is not currently known to be facing any threats, and is itself a threat to many other species outside of its native range, making it a major conservation problem (7). In just under 20 years, the killer shrimp has colonised most of continental Europe, and is now recognised as one of the region’s worst invasive species (7).
In the UK, the killer shrimp was first recorded in September 2010, in Grafham Water Reservoir, Cambridgeshire (1) (2), and has since become established (1). There are two further recorded infestations in the UK, both of which are in Wales (1). There are serious concerns about the continued spread of this destructive species, as the UK contains large areas of suitable canal, river and lake habitat in which the killer shrimp would thrive (1) (4). Further invasions, either in the UK or elsewhere, could have ecological or economic consequences (1) (6).
The killer shrimp is able to colonise new areas through a variety of different pathways. In addition to the killer shrimp being able to disperse downstream by natural drift (1), the recent expansion of European waterway networks and increases in shipping traffic are likely to facilitate this species’ invasion of new areas (1) (3) (4) (6) (7). This species has a high ability to remain attached to objects (7), such as scuba-diving and recreational boating equipment, and is also known to be carried in ballast water (1) (7).
The killer shrimp has several traits which make it a good invader, including its highly predatory behaviour, rapid growth, early maturation and high reproductive output (4) (6), as well as its ability to survive harsh transport conditions and being out of water for up to three and a half days (7). It threatens native species diversity through predation or competition (1) (3) (5), and in areas where the killer shrimp has established itself as an invasive species, it has placed pressure on local ecosystems, leading to the decline or even extirpation of native species (4) (7). The killer shrimp has been identified as a species which could affect the quality and distribution of fisheries, either through altering the environmental conditions or through carrying parasites which may negatively affect fish stocks (1).