Aquatic insect adaptations to winter cold and ice.

Abstract

Abstract Most aquatic habitats in cold regions are frozen or covered by ice during winter. Aquatic insects survive these cold and icy conditions by a variety of adaptations. Different species move seasonally between habitats, choose particular overwintering sites, modify local conditions by constructing shelters, and withstand the effects of ice break-up and flooding during the spring thaw. Limited data indicate that several kinds of aquatic insects withstand subfreezing temperatures while surrounded by ice. Some of these species supercool and others tolerate freezing. A review of the available information in the context of recent discoveries in insect cold hardiness suggests fruitful avenues for research, including the roles of dehydration and of antifreeze proteins. Also required is study of the cold hardiness of individual species in relation to habitat conditions, seasonal movements and mechanical protection by overwintering structures. We need even basic information about the production and interaction of cryoprotectants, which are scarcely known compared with those of terrestrial insects. Therefore, detailed biological information must be collected about individual species of aquatic insects (in contrast to some current preferences for generalized statistics about aquatic systems) and put into a wide life-cycle context.