SLELO PRISM

The Spiny Waterflea (Bythotrephes longimanus) is crustaceous zooplankton of the suborder Cladocera. It is native to freshwater lakes in northern Europe and Asia. Both in their native range and throughout the regions in which they have been introduced, the spiny water flea prefers large, deep lakes whose benthic zones have relatively low summer temperatures. Nevertheless, they can also be found in shallower lakes, as well as rivers.

They were introduced into the Great Lakes by the discharge of ballast water from ocean-traveling ships and were first discovered in Lake Ontario in the early 1980s. Local dispersal methods of the spiny water flea include swimming between continuous bodies of water and being moved via anglers and recreational boaters to inland lakes.

Impacts

Spiny waterfleas disrupt the food web by preying upon zooplankton— particularly daphnia. Being an important food source for juvenile native fish,  loss of zooplankton may result in reduced growth sizes in fish like perch and walleye. Water clarity may also be reduced due to the loss of zooplankton.

Habitat/Distribution:

Spiny water flea prefers deep lakes but can be found in shallow lakes and rivers. They can collect in globs on fishing lines and downrigger cables. It is distributed in freshwater sources throughout the northeastern United States. It was found in Lake Huron in 1984, Lake Ontario and Lake Erie in 1985, Lake Michigan in 1986, and Lake Superior in 1987.

Identification: 

Spinywater fleaa have a hard outer shell. The species’ most noticeable feature, however, is its long tail spine. The spine makes up 70% of its total body length and contains 1-4 pairs of thorn-like barbs. Their head consists primarily of a single, large eye and a pair of mandibles. The spiny water flea has four pairs of legs, the first pair being considerably longer than the others.

The spiny water flea shares its large tail spine characteristic with a confamilial (shared taxonomic family origin), the fishhook water flea (Cercopagis pengoi). To differentiate these two water fleas apart compare their body sizes and the terminal shape of their tail spines. The spiny water flea is much larger than its fishhook relative and possesses a more robust spine. Additionally, as its name suggests, the end of the fishhook waterflea’s tail spine has a fishhook-shaped curve, which is not found on the spiny water flea. The spiny water flea can reach body lengths of up to 15 m