Factors regulating periphytic algal biomass

To assess the principal factors regulating periphytic algal communities, I conducted a field study along a productivity gradient of Swedish and Antarctic lakes ranging from extremely low productivity meltwater to highly productive lakes. Because the Antarctic lakes lack fish, as well as molluscs and insect larvae, the data set provides considerable variation in food web composition, offering a rare opportunity to evaluate the importance of these factors in determining the biomass of periphytic algae. Among the possible factors investigated, water temperature, substrate characteristics, and food web composition seem to be of minor importance. Instead, there was a curvlinear relationship between the biomass of sediment‐associated periphytic algae and lake productivity, suggesting a shift from nutrient limitation to light limitation caused by phytoplankton. A temporal study in the littoral zone of one of the lakes included in the spatial study showed that the temporal variation in periphyton biomass within the lake was low compared to the variation between lakes. The temporal study also strengthened suggestions from the spatial study by pointing to nutrient availability as a major factor determining periphytic algal biomass.