Field determination of the critical nutrient concentrations for Cladophora in streams and their importance in waste load management

Year of Publication
Many streams in Southern Ontario are seriously infested with excessive seasonal growth of aquatic plants such as Cladophora and Potamogeton. A direct relationship, with a regression coefficient of 0.87, was observed between ambient P concentration in the water and P content of plant tissue in six rivers. Critical or growth controlling total P concentration of 60 lug/ in stream water and l. 6 mg/g dry weight in plant tissue were determined. Unlike P, no Significant correlation was observed between N content of plant tissue and N concentration in water. The correlation of total P with plant growth can be used to estimate the waste load which would result in maximum growth rate of Cladophora.