LABORATORY-BASED INVESTIGATION INTO THE POTENTIAL FOR ALGAL PROLIFERATION IN LAKE COLEMAN, VICTORIA

Lake Coleman received a discharge of highly coloured, treated pulp and paper mill effluent and domestic and industrial effluent from 1958 un til the latter part of 1992. The colour of the lake waters is likely t o become less intense following cessation of the discharge and this ma y affect the potential for algal growth. The estuarine diatom Phaeodac tylum tricornutum was cultured in a range of concentrations of Lake Co leman water with and without pre-exposure to nutrient-rich Lake Colema n sediments. Under laboratory conditions, growth of P. tricornutum was significantly enhanced in Lake Coleman water compared with cultures g rown in water collected from an adjacent unpolluted lake. Growth was f urther enhanced in solutions with additional pre-exposure to Lake Cole man sediments. Growth enhancement exhibited a linear relationship to s olution orthophosphate concentrations. When the diatom was cultured un der a range of light intensities produced by a range of dilutions of L ake Coleman water, growth was significantly reduced by high colour int ensity. The possibility exists, therefore, for enhanced algal prolifer ation in Lake Coleman following cessation of effluent discharge.