Ciliate community structure in the zone of mixing sea and river waters [Russian]

摘要

The structure of a ciliate community was investigated in a White Sea estuary. The great environmental variability and distinct salinity gradient (0-22 parts per thousand) characterize this estuary. The ciliate communities in different estuary sites represent variable combinations of both marine and brackishwater species. They substitute for one another depending on changes in the water salinity and other environmental factors (pH, Eh, organic, matter content, and grahulometric composition of sediments). Marine euryhaline species predominate in biotopes with higher water salinity (>7-9 parts per thousand), brackishwater (oligohaline) ciliates, in sites with lower salinity, and freshwater species occur sporadically. Within the estuary, from the sea toward the river, values of all integral community characteristics (biomass, abundance, species, diversity, and mean size) and the percentage of algivorous ciliates decrease. As compared to macrobenthos, marine ciliates penetrate deeper into the freshwater part of the estuary, and the boundary between the marine and brackishwater ciliate communities is shifted toward the river.