Notes on the phytoplankton periodicity of Rostherne Mere, Cheshire, 1967–1977

Information on the phytoplankton periodicity in Rostherne Mere during eight of the last eleven years is presented. Microcystis aeruginosa was overwhelmingly dominant in five summers; Ceratium dominated in two of the remaining years; diatoms and Anabaena spp. were the most abundant forms in the other year. Algal biomass was generally low in the first half of each year.