Orconectes limosus (Rafinesque, 1817) Status
Now found in Cape Breton, currently only in Freshwater Lake
Mottled green to brown in color, sometimes appear black (due to living in burrows amongst sediment)
May have red markings on abdomen and claws
Has small spines on the ‘cheeks’ or side of the carapace
this is the only crayfish species in Nova Scotia
The spinycheek crayfish is a freshwater species that is tolerant of a range of stressful physical conditions, including polluted environments. It tends to thrive in freshwater lakes, streams, and ponds. The crayfish prefers vegetated and turbid waters, on silty or muddy bottoms where they burrow into the substrate. In some areas in Canada the spinycheek crayfish has been found to inhabit stony streams with moderate current. The species can tolerate drying conditions for weeks and even move across land for brief periods of time.
This crayfish is native to northern parts of the United States from Maine to Virginia. Introductions which have resulted in established populations date to early 1890 in Europe starting with Germany. In the United Kingdom popluations have been established since 1995. Today it is one of the most common crayfish and can be found in more than twenty European countries. In Canada, the spinycheek crayfish has been introduced to areas of New Brunswick and Quebec near the United States border.
The spinycheek crayfish is thought to have been introduced into Freshwater Lake, Cape Breton Highlands National Park, Nova Scotia, sometime after 2002. This is the first and only known introduction of this invasive crayfish within Nova Scotia.There are two vectors which may have caused this introduction. Firstly, this crayfish is popular live bait among fishermen. Accidental or intentional release of live bait may have lead to the invasion. Secondly, as with many introduced species, this crayfish is popular as both an aquarium pet and aquarium food source. Therefore, the spinycheek crayfish may have also been accidentally or intentionally released into Freshwater Lake as a result of the aquarium trade.
In an introduced habitat, spinycheek crayfish can have detrimental effects on local populations of both aquatic plants and animals. In Europe the introduced crayfish has been competing with local species and is a known carrier of a water mold known as crayfish plague. The crayfish has been known to affect aquatic plants, insects, snails, and fish. At risk in Freshwater Lake in the Cape Breton Highlands are rare freshwater snails called valve snails (Valvata sincera), that call the body of water home. Even in relatively low numbers these crayfish can pose a significant threat to aquatic biota. However, with the low number of natural predators in the lake, populations are increasing rapidly. Freshwater Lake is currently closed to fishing to help increase populations of brook trout (Salvelinus fontinalis) which are a natural predator of the crayfish. Trapping is also scheduled to be performed in the lake during 2008-2009 to remove some of the spinkcheek crayfish.
Additional articles and website about spinycheek crayfish locally and globally:
- Parks Canada website for Spinycheek crayfish
- Downloadable Spinycheek crayfish brochure for Cape Breton Highlands National Park from Parks Canada
- Announcement of the Environmental Assessment of Spinycheek Crayfish in Freshwater Lake, Cape Breton Highlands
- "The spinycheek crayfish digs into the United Kingdom" - a scientific article from the journal Aquatic Invasions