An approach to the synthesis of qualitative ecological information from aquatic coleoptera communities

A list of 196 Coleoptera taxa, larvae and adults, covering 113 species, was obtained from several surveys of a flood plain of the Rhô river. From published reports and personal experience, each taxon is linked with the modalities of nine environmental and three biological variables. The resulting 12 ecological profiles for 196 taxa are analysed by correspondence analysis. The simultaneous ordination of the taxa and variables allows presentation of the more synthetic correspondence between the Coleoptera and their ecological and biological characteristics. The niche dimensions of the 12 variables tested here are organized along a current-substrate gradient, from stones in rapid flow to mud in still water, which is associated with the other ecological conditions. This ordination reflects environmental conditions in a transverse direction, particularly from the central channel to the furthest annexes of the river. The Coleoptera are shown to be describers of the connectivity with the main channel. The 196 studied taxa are positioned along the gradient. They are subdivided into seven faunal groups based on their habitat range or niche width. The larger species are confined to the stagnant side of the gradient. Other variables, such as feeding and vertical distribution, clearly separate carnivores from herbivores and also larvae from adults. The next step of this study will be to extend these investigations to other functional variables and to all the species of Coleoptera in France. The information given by the Coleoptera will then be compared with actual field measurements.     

The use of coleoptera (arthropoda:insecta) for floodplain characterization on the River Trent,U.K.

Following a long history of floodplain degradation, directly or indirectly as a result of river regulation, international attention is turning to the restoration of these ecologically important ecotones. One immediate problem is to assess the ecological value of different floodplain habitats. With reference to two floodplain sectors—one non-regulated and one regulated—on the River Trent, U.K., this paper characterizes the dominant floodplain units using two families of beetles (Coleoptera: Carabidae and Staphylinidae). Five dominant habitat units, riparian, wetland, woodland, pasture, and arable, are clearly differentiated by both families using ordination analyses. Although the faunal assemblages of specific units within the two sectors have many similarities, the units within the regulated sector are more clearly differentiated, having larger assemblages of ‘describer’ species. It is suggested that the enhanced environmental gradients between units within this sector may be responsible for stronger faunal contrasts.