PALEOLIMNOLOGICAL ANALYSES AS INFORMATION SOURCE FOR LARGE LAKE BIOMONITORING

A routinely applicable palaeolimnological sampling and analysis progra mme for large lake monitoring was developed as part of the Lake Saimaa Biomonitoring Project (1990-1993). The scope of palaeolimnological an alyses is to gain background information of the recent past (ca. 0-200 yr) of the lake ecosystem that is being monitored. We analyzed short sediment cores from three contrasting basins of the complex lake Saima a in eastern Finland (nutrient-poor clearwater Lake Puruvesi; oligotro phic mesohumic Lake Paasivesi, and eutrophied and polluted mesohumic L ake Haukivesi). Each basin shows a unique developmental history under the various forms of human influence on the ecosystem. The following r esearch approaches are evaluated in the study: echosounding, dating (P b-210, varves, soot stratigraphy), element stratigraphies, biological remains (diatoms, cladocera, chironomids, sedimentary pigments).