Growth of aquatic plants in the Avon River

Abstract

This report documents heavy growths of aquatic plants in the Avon River in 1980 and 1981, which were heavier than in most other Southern Ontario rivers. The heavy growths were apparently being sustained by high levels of phosphorus in conjunction with other favourable growing conditions. Phosphorus in samples of plant tissues was well in excess of the level that would limit growth. The total river biomass, which averaged 49,550 kg during the months of May to August, was demonstrated to be the major cause of low night-time concentrations of dissolved oxygen in river water. During darkness, the oxygen demand from aquatic plants was approximately thirty- six times the oxygen demand from the Stratford WPCP effluent.