The Loch Eil project: Population characteristics of ciliate protozoans from organically enriched sea-loch sediments

Abstract

The population characteristics of marine, benthic ciliate protozoans from the sediments of Loch Eil and the Lynn of Lorne on the west coast of Scotland were investigated in relation to the effect of effluent discharge from a pulp and paper mill. During the 12-month field sampling programme, differences in population density, species occurrence, and diversity were found between the ciliate communities from sediments subjected to varying degrees of organic enrichment. These differences did not seem to be related to changes in temperature or any other seasonal factor or to fluctuations in the benthic meiofauna or diatoms. The largest and most diverse ciliate populations were found in the most polluted sediments and typically included microaerophilic species characteristic of sulphureta. Variations in ciliate population density in the samples from the station nearest the effluent outfall were correlated with effluent discharge during the preceding month. The sediments from the Lynn of Lorne were very sparsely populated. The occurrence of benthic ciliates in relation to a gradient of organic enrichment is discussed and a succession of ciliate species along such a gradient is suggested.