Original paper

The effect of sedimentation on the benthic community of Lake Brunnsee

Bergtold, Matthias; Traunspurger, Walter

Abstract

The flux of settling particles to the sediment was manipulated in a field and laboratory experiment. In the field, sedimentation rate was reduced in experimental areas by a factor of 2.3 by covering the bottom of the lake. Sedimentation rate, bacterial parameters, as well as protozoan and metazoan abundance were recorded over a period of 8 month. The benthic community showed strong seasonal variation but did not respond to the reduced sedimentation rate in the field. In autumn, undisturbed sediment cores from the study site were transferred to the laboratory. Material from the lake was collected in sedimentation traps and continuously added to half of the cores over a period of 3 months. Controls received no material. The abundance of flagellates, ciliates and nematodes was higher in the treatments receiving material from the lake, though the effect was restricted to the uppermost sediment layer (0–0.5 cm). This study shows that sedimentation was of minor importance for the population dynamics of the organisms in the field, but turned out to be an important factor for a specific part of the benthic community under controlled laboratory conditions.

Keywords

sedimentationfreshwater sedimentbacteriaprotozoameiobenthosmacrobenthos