Nematodes of Lake Constance, Germany, with special reference to littoral communities of a river mouth area

Six sites within the littoral habitat of Lake Constance in Germany were studied from February 1999 to January 2000 in order to determine the influence of the inflowing River Schussen on local nematode assemblages. The sites were selected to represent a gradient of river influence within the broader river mouth area. The area as a whole was found to be rich in nematode diversity, with 106 nematode species identified. The nematode communities recorded ranged in density from 121 to 165 individuals/10 cm(2) and in biomass from 108 to 503 mu g wet weight/10 cm(2). They were also shown to vary in terms of feeding ecology, with significant differences in the proportions of feeding types occurring among site. Deposit feeders were most abundant, followed by chewers, although the latter dominated in terms of biomass. Epistrate feeders were less common and suction feeders rare. The occurrence of epistrate feeders was linked to the concentration of algal pigment, whereas records of deposit feeders and chewers correlated with bacterial density and organic carbon content. The characters of the different nematode communities in the vicinity of the river mouth were found to reflect the transitional nature of the study area.