Temporal and spatial distribution of chironomid larvae and oligochaetes in two Dutch storage reservoirs

Abstract

Long-term changes in distribution and taxonomic composition of chironomid larvae and oligochaetes in two water storage reservoirs in The Netherlands were studied. A succession among the chironomid spe-9 was observed. In the last 10-15 years chironomid densities varied. Compared with other lakes chironomid densities were high. Densities of chironomids were higher in the littoral zone than in the profundal zone. The opposite was found for oligochaetes. Densities and composition of the chironomid fauna in the two reservoirs were similar. Proc/adius, Tanytarsus and Harnischia dominated at all depths. However, pupal exuviae samples showed some differences in chironomid taxonomic composition between the two reservoirs. Orthocladiinae, rarely found in bottom samples, abounded in pupal exuviae samples.

Chironomid pupal exuviae and larvae of two storage reservoirs in The Netherlands

“…For the Biesbosch reservoirs this is clearly demonstrated by KETELAARS et al (1992). It appeared that the distribution pattern of oligochaetes in two reservoirs differed considerably.…”

“…Parts of the results of this research are discussed in detail elsewhere in this volume (KETELAARS et al, 1992). Here some pros and cons of the two sampling methods are discussed.…”