A Study of the Phytoplankton of a Calcareous River

Abstract

A 2-year quantitative study of the phytoplankton of the canalized River Lee, Hertfordshire was carried out. with weekly algal counts, temperature and chemical determinations from several stations. The benthic diatom population showed no marked seasonal periodicity. The plankton dominant, Stephanodiscus hantzschii, showed spring and autumn maxima, whose size was inversely related to the rate of flow of the river. The concentration of chemical substances was consistently high and none appeared to be limiting. Hot effluent discharging into the river from an electricity generating station seemed to have no detectable influence on the time of onset or the size of photoplankton populations, neither did the effluent from a sewage treatment plant which opened during the course of the investigation.