Description:
<p>In a study of three acidified lakes, we found a clear habitat separation between the three most abundant corixid species. Cymatia bonsdorffi had a pronounced littoral habitat and Arctocorisa germari a limnetic habitat. No significant overlap between the habitats of these two species was found. The third species, Glaenocorisa propingua, was less specialized in its choice of habitat and utilized both types. Glaenocorisa propinqua and Arctocorisa germari showed adaptations to a limnetic mode of life such as relatively high swimming velocity and low frequency of surface visits. Characteristic features of the corixid community in acidified lakes are also discussed. Some species of waterbugs (Corixidae, Hemiptera-Heteropteta) are suitable prey organisms for fish and are not adapted to co-existence with fish predators. These species are not found in lakes containing fish but are abundant in fishless waters such as many acidified lakes.</p>