Journal of plankton research vol:15 issue:10 pages:1129-1139
The horizontal distribution of Scapholeberis mucronata in a small pond was studied by transect and pattern sampling. Densities are high (>1000 animals m(-2)) in the littoral zone and low in the open water (no aquatic vegetation; <50 animals m(-2)). The preference for the littoral zone is, however, less well expressed during the night, indicative of a diurnal horizontal migration. Within the littoral zone, the distribution of Scapholeberis is highly aggregated. The relative degree of patchiness is inversely correlated with density. The relative abundance of males and ephippial females was not invariably higher in than out of patches. It is hypothesized that the observed habitat preference, as well as the aggregative behaviour, of Scapholeberis are mechanisms to avoid predation by fishes.