The ecology of the family Chydoridae (Branchiopoda, Anomopoda) and its application to lake monitoring

Abstract

Chydorids (Branchipoda, Anomopoda) were sampled from twenty nine Irish lakes between June 1996 and July 1997, in order to assess the usefulness of this group as indicators of lake ecological quality. The lakes represented a wide range of the physicochemical conditions found in Irish lakes, and thirty one species of Chydoridae were identified from a total of 260 samples. Multivariate analysis was used to elucidate relationships between the chydorids and their environment, and in particular, what aspects of the lakes system had strong effects on the chydorid community structure. It was found that the ecological quality of the twenty nine lakes could be characterised successfully by the chydorid communities sampled. The main factors affecting the community structures were found to be the trophic status of the lake, the acidity/alkalinity of the water, and the amount of physical disturbance in the littoral region. Several species (Alona affinis, Alonopsis elongata, Chydorus sphaericus and Monospilus dispar) were found to dominate the chydorid community in lakes which were under some kind of environmental stress, and in lakes where this stress was not so significant, the community was richer and more diverse. A dichotomous key, based on the dominant species of chydorid and the diversity of the community is described, which could be used to assess the ecological quality of a lake.