Succession of phyto- and zooplankton in a wastewater storage reservoir

Summary

Storage of secondary treated wastewater in an open reservoir can provide clean water for summer irrigation. After initial development of dense population of Chlamydomonas and Euglena, there was decline in algal density. During the irrigation season the algal biomass was 1–2 mg (dry weight) per liter, mostly Ankistrodesmus. Herbivorous zooplankton consisted mainly of Daphnia and Brachionus. Toward end of the summer there was a decrease in zooplankton followed by a secondary algal bloom dominated first by Euglena and later by Spirulina. During the entire storage period the reservoir contained dissolved oxygen and no odour or other nuisances were reported.