A Biological Study of a Temporary Pond in Western Canada

Abstract

Near Winnipeg the melting snows of April fill a depression 100 X 500 ft. to a depth of some 3 ft., but this temporary pond dries out completely in June; its bottom in summer is overgrown by flowering plants and in winter is covered with snow (-35[degree] F.) and is frozen 7 ft. deep. This pond in 1925-1927 was swarming with aquatic life; some 80 sp. are listed, most of which lie dormant 9 mo. of the yr. The dry period enables the plants of the pond bottom to store up energy to be used by the biota of the following spring. Individual diversities in the molluscs are assigned chiefly to internal factors and not to this phenomenal environment.