An Observation of the Overwintering Aquatic Insects in a Prairie Pond in Saskatchewan, Canada

Abstract

In temperate regions freshwater insects annually face the challenge of surviving the winter months or otherwise perishing. Ice formation presents a substantial danger to all life stages, from the eggs to adults. Accordingly, some species have adapted to overwinter within ice and emerge during the spring thaw. The diversity of aquatic species encased in the ice and frozen sediment of a prairie pond in Saskatchewan, Canada and their survival rate upon thawing was assessed in the winter of 2013. A total of 164 specimens were retrieved from the ice and sediment, 73 of which survived after thawing. Survival rate was greatest for Cymatia americana (Corixidae, Hemiptera) at 79.6%. Corixids were found in distinct clusters encased in pond ice, a phenomenon not well documented in previous literature. A higher rate of survival was expected among the chironomids, although the value falls within ranges observed in previous studies. Additionally, members of other taxa including Notonectidae (Hemiptera), Haliplidae (Coleoptera), Ceratopogonidae (Diptera), and Coenagrionidae (Odonata) were recovered; however, these specimens exhibited much lower rates of survival.