
An American crayfish in London (and beyond!)
by Zara Gladman, PhD student at the University of Glasgow and intern at the Society of Biology In my last blog I waxed lyrical on the wonders of crayfish, those large freshwater invertebrates that grace our rivers, lochs and your M&S sandwiches. Today I’d like to discuss one of the biggest threats to aquatic biodiversity: the introduction of non-native crayfish to new ecosystems. For the past four years, my life has been devoted to learning everything I can about one such invader, the North American signal crayfish (Pacifastacus leniusculus, pictured right). Originally from western North America, this species was imported into Sweden for aquaculture in the 1950s and 60s. Thereafter, introductions were made to several other countries including the UK. Today, the signal crayfish is the most widespread non-native crayfish species in Europe. This is not good news for our native plants and animals. Signal crayfish are large, mobile “keystone…