Saskatchewan Aquatic Insects

In Saskatchewan twelve major groups, or orders, of insects have members that live a part of their lives in or on the water. They include: Collembola (Springtails), Ephemeroptera (Mayflies), Odonata (Dragonflies and Damselflies), Plecoptera (Stoneflies), Hemiptera (True bugs), Coleoptera (Beetles), Trichoptera (Caddisflies), Lepidoptera (Moths), Megaloptera (Dobson flies), Neuroptera (Spongilla flies), Diptera (True flies), and Hymenoptera (Wasps).

The flora and fauna of Canada and most of Saskatchewan were eliminated by the advancing ice sheets of the Wisconsin glaciation (100,000 to 17,000 BP)(Pielou 1991) (Click on thumbnail of map to the right). In what is now Canada only areas in the northwestern arctic (Beringia), and small areas on the extreme west coast, the mouth of the St. Lawrence and Maritimes and the Cypress Hills and along the Montana-Saskatchewan border were free from ice. To the south of the ice sheet three general regions acted as refugia; the temperate southeast from the east coast of North America to the Appalachians and Mississippi River; the central region between the Mississippi and the western mountains; and the Pacific mountain refugium. The aquatic insect fauna present in Saskatchewan today is the result of immigration (red arrows on map) from these refugia into the province after glaciation (Lehmkuhl 1980). Periods of glacial advance and retreat severed and re-established links between Saskatchewan and the three southern refugia and Beringia as well as the eastern Canadian refugia (Christiansen 1979, Flannagan and Flannagan 1982, Pielou 1991). As the ice sheets retreated the flora and fauna began recolonizing the newly exposed regions. Due to its geographical location in the continent Saskatchewan has an aquatic insect fauna that originated from all of the major refugia but the majority have colonized from the three refugia to the south (Lehmkuhl 1980).

Aquatic insects are a major component of the biodiversity of the province. Over 1200 species of aquatic insects are known from Saskatchewan (Parker and Lehmkuhl, 1999). This makes them much more diverse than many other aquatic and terrestrial groups of organisms found in the province. These insects, and other aquatic macroinvertebrates, form an integral part of aquatic ecosystems. They recycle much of the decaying plant and animal material back into the food web. They are important food for fish and waterfowl. When the adult insects emerge from the water they are important food for popular insectivorous birds. Many of the familiar biting insects (mosquitoes, blackflies, horseflies, deer flies and no-see-ums) start their life cycles in lakes, ponds, rivers and streams.

Because they are such an important part of aquatic ecosystems aquatic insect communities, and other macroinvertebrates, are used to determine the impact of developments (mines, forestry) or to assess the effects of contaminants (pesticides, sewer effluent, etc.) on the natural environment. They are used in this role because they are diverse, each species reacts to pollutants in a characteristic manner, they respond quickly and they are relatively sedentary so they can not effectively leave the contaminated area.

However, our knowledge of most aquatic insects and aquatic macroinvertebrates found in Saskatchewan is poor. A number of insect groups (Ephemeroptera, Hemiptera, Plecoptera, Culicidae, Simuliidae, Odonata) were comprehensively examined in the province between 1965 and 2000, but these treatments are now very dated with regard to taxonomic names, distributions and ecologies. A thorough examination of the various groups is required to update the changes in taxonomies and improve our knowledge of their distributions and biologies in the province. Unfortunately, in the present climate of research that pervades our museums, academia and industry it is very likely this lack of knowledge will persist for many years and decades to come.

REFERENCES

Christiansen E.A. 1979. The Wisconsin deglaciation of southern Saskatchewan and adjacent areas. Can.J.Earth Sci. 16:913-938.

Flannagan, P.M. and J.F. Flannagan. 1982. Present distribution and post-glacial origin of the Ephemeroptera, Plecoptera and Trichoptera of Manitoba. Manitoba Dept. of Nat. Res. Fish. Tech. Rep. No. 82-1.

Lehmkuhl, D.M. 1980. Temporal and spatial changes in the Canadian insect fauna: Patterns and explanations. Can. Ent. 112:1145-1159.

Parker, D.W. and D.M. Lehmkuhl, 1999. Diversity of aquatic macroinvertebrates in Saskatchewan. In. Thorpe, J., T.A. Steeves, and M. Gollop. Proceedings of the 5th Prairie Conservation and Endangered Species Conference. Saskatoon, SK. Feb. 19-22, 1998. Natural History Occasional Paper No.24.Provincial Museum of Alberta, Edmonton, Alberta. Pp. 306-311.

Pielou, E.C. 1991. After the Ice Age: The Return of Life to Glaciated North America.University of Chicago Press, Chicago.