Distribution and ecology of non-planktonic brackish-water rotifers from Scandinavian waters

Abstract

The distribution and ecology of benthic and periphytic Rotifera were studied in some brackish-water localities in the Baltic Sea and in the inner Danish waters. A total of 34 species were found. The food of different species was studies. Carnivores and species feeding on protophytes play the greatest role, bacterivores are fewer. Several species are very specific in their choice of food. The salinity range of some rotifers was studied experimentally and the results were in good agreement with the field distributions. All species are extremely euryhaline and several species are able to live in the salinity range 0–32 %. In the field the number of species decreases with increasing salinity. The quantitative and qualitative occurrences of rotifers in the sands of the shallow Nivå Bay in the Øresund were studied through a year. The rotifers play a modest quantitative role in marine and brackish-water sands (< 10 specimens/cm²) and this is in contrast to what is found in freshwater. Greatest species diversity was found in late summer. In the marine environment rotifers seem to play a larger role in detritus and in algae than they do in sands in accordance with the fact that rotifers in general lack morphological adaptations to interstitial life.