ZOOPLANKTON CHARACTERISTICS IN MONITORING OF LAKE-LADOGA

The potential of limnetic zooplankton as a bioindicator in large lake ecosystem monitoring is illustrated with reference to Lake Ladoga. Pat terns of change in the very long record of pelagic summer zooplankton in Lake Ladoga, spanning the years 1948-1993, are presented. This data is complemented with records of near-shore zooplankton communities fr om the past decade, the changes of which are discussed with special re ference to two contrasting littoral areas: the southern bays, and the northern archipelago. In the pelagic zone the zooplankton community sh ows great stability throughout the entire monitoring period. According to zooplankton, the trophic state of the pelagial region may be class ified as oligo-mesotrophic, with only a slight trend of eutrophication evident in the uppermost water layers. In the littoral zones more pro minent eutrophication is indicated.