CAN CHARA CONTROL PHOSPHORUS CYCLING IN LAKE LUKNAJNO (POLAND)

Waters of Lake Luknajno (623 ha, 3 m max. depth postglacial basin in M asurian Lakeland) are of meso-eutrophic type in spite of an intensive land impact and substantial phosphorus loading. The reason of this pec uliarity is an abundance of 4 species of charophytes (Chara aculeolata , C. aspera, C. contraria and C. tomentosa) which dominate the submerg ed vegetation of the lake and yielded 417 g m-2 dry biomass in summer 1991. The plants have high potential for phosphorus uptake and accumul ation as was checked in laboratory experiments. Due to this potential Chara can outcompete planktonic algae in mixed cultures at different m ineral P supplies.