Ref ID : 1355
J.M. Schmid-Araya; Disturbance and population dynamics of rotifers in bed sediments. Hydrobiologia 313/314:279-290, 1995
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Rotifers inhabiting the sediment surface and the hyporheic interstitial of a gravel stream were investigated between October 1991 and October 1992. At the sediment surface, samples were taken with a modified Hess sampler at five randomly chosen sites and at roughly weekly intervals. In the hyporheic interstitial, samples were collected using standpipe traps permanently installed at two sites at four sediment depths (0-40 cm), and every fifteen days. The distribution of five rotifer species revealed different temporal and spatial patterns. Two species, Notholca foliacea (Ehrb.) and Notholca squamula (O.F.M.) co-occured having their temporal peaks at the beginning of summer and in autumn. Cephalodella gibba (Ehrb.) and Proales theodora (Gosse) occurred throughout the year, while Parencentrum longipes (Wulf.) showed a clear peak during the spring only in the hyporheic interstitial. The effect of variables such as water level, surface discharge and variation of the groundwater level was tested upon the densities of each species. Despite the spring spate, the species are able to persist due to the presence of low-flow refuge habitats or the dispersion into deeper layer of the hyporheic interstitial.