Light climate in the Gippsland Lakes, Victoria

Abstract

Variation in the light climate of Lakes Wellington, Victoria and King, Gippsland, Vic. occurred both seasonally and between the three lakes studied. Absorption of photosynthetically active radiation was related primarily to concentration of non-chlorophyllous particulate material (tripton) with dissolved organic material (gilvin) and particulate chlorophyll being of lesser importance in influencing light climate. Lake waters were characterized by selective attenuation of red (650-700 nm wavelength) and blue (400-500 nm wavelength) quanta with depth.

.Though most photosynthetically active radiation in Lake Wellington was removed in the first 1 m of depth, phytoplankton biomass was higher than in Lake King which had more available light. Vertical mixing, resulting in periodic exposure of phytoplankton to surface light levels, is suggested as a mechanism whereby the relatively high phytoplankton biomass of Lake Wellington is maintained.