Some Observations on the Ecology of Desmids

Abstract

A study of a shallow lake that was rich in species of desmid showed a division into euplanktonic and facultatively planktonic desmids to be unreal, though a real distinction was found between these two groups together and non-planktonic desmids. Several of the "plank-tonic" species were observed multiplying both on the sediment and in the open water. Unialgal cultures were used to investigate flotation and the value of mucilage sheaths and processes, and the sinking rates of populations of several species grown under different conditions were compared experimentally. The results agreed with the accepted views concerning the ecological behavior of the species.