New cyclopoid copepod (Thermocyclops crassus) reported in the Laurentian Great Lakes

The cyclopoid copepod Thermocyclops crassus, native to Eurasia and Africa, was detected at two sites in the western basin of Lake Erie in August 2014. T. crassus was subsequently detected in samples collected from two sites in western Lake Erie in August 2015 and four sites in August 2016. Densities of adult T. crassus remained relatively low but increased each year, averaging 1.3 individuals/m3 in 2014, 12.8 individuals/m3 in 2015, and 35.5 individuals/m3 in 2016. The only other documented occurrence of T. crassus in either the United States or Canada has been in Lake Champlain's Missisquoi Bay in 1991. This is the first finding of an exotic species introduced into the Laurentian Great Lakes since the discovery of Hemimysis anomala in Lake Michigan in 2006.