Effectʹs of cadmium and metal-contaminated sediments on photosynthesis, heterotrophy, and phosphate uptake in macienme river delta phytoplankton

Elutriate-based bioassays indicated that disposal of dredged sediments from four Mackenzie River Delta locations into Mason Bay would not significantly affect phytoplankton photosynthesis in spite of elevated concentrations of cadmium and other metals in the sediments. Elutriates also had no effect on photosynthesis of P-sufficient Chaetoceros but stimulated photosynthesis in P-deficient cultures. Cadmium up to 5 μg/L was not inhibitory to photosynthesis of phytoplankton or Chaetoceros cultures but heterotrophy, and algal, but not bacterial, phosphate uptake was depressed. Heterotrophic glucose uptake by natural communities was inhibited by elutriates and by Cd. Elutriates were found not to model accurately the effects of sediment disposal on phosphorus cycling.