The regulation of blue-green algal buoyancy in four eutrophic swedish lakes

Abstract

The variation in the percentage of buoyant cells of planktonic blue-green algae was studied in 18 populations from four eutrophic lakes. The highest proportion of the population in a buoyant condition usually occurred at the beginning and end of the population development. The variation in mean buoyancy was significant between lakes but not between species, indicating that environmental factors were decisive. Large variations in the percentage of cells floating (0-100%) occurred within a short time (3-4 days) and were negatively correlated with the phosphorus (P) content in the cells, which also had large variations. A higher percentage of floating cells occurred when the P content was low. The same relationship explained the variation in mean percentage of buoyant cells between lakes.The inability of the blue-green algae to maintain a high and even P content in their cells seems to be the main reason for the observed variations in buoyancy. © 1983, British Phycological Society.