Ref ID : 6659
Piet F.M. Verdonschot; Micro-distribution of oligochaetes in a soft-bottomed lowland stream (Elsbeek; The Netherlands). Hydrobiologia 406:149-163, 1999
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This study focuses on a low-gradient, soft-bottomed stream which shows strong fluctuations in discharge, partly natural (i.e. due to rainfall) and partly due to agricultural land-use. This dynamic discharge pattern causes silt deposition between discharge peaks which in turn cause the silt to be washed out. This process occurs independently from the height of the peak. The main substrate in the stream is quite homogeneous fine sand. Twenty-three species of oligochaetes were found. Their distribution and abundance varied with season and substrate. Mature tubificids and Lumbriculus variegatus occurred throughout the year. Stylodrilus heringianus occurred in winter and spring. Different naidids occur in different season, though half of the species can be collected all year. The micro-habitat of three tubificids, one lumbriculid and eight naidids were be identified. A high number of oligochaete species coexisted in a small stretch of the stream due to a separation in micro-habitat in space and time. The temporal variation in distribution was due to season. Particle size, the mineral and organic component of the substrate, and position in the stream bed influenced the spatial distribution of species. Temporal and spatial distribution of oligochaetes can not be separated.