The influence of dissolved organic carbon (DOC) and calcium on the toxicity of copper and nickel to the freshwater alga Selenastrum capricornutum and the zooplankter Daphnia magna.

Abstract

The toxicity of copper and nickel was measured in algal cultures of Selenastrum capricornutum and zooplankton cultures of Daphnia magna to determine if dissolved organic carbon (DOC) and/or calcium concentrations can influence toxicity of these two metals. Water samples were collected from the Raisin River (high DOC and high calcium), the St. Lawrence River (low DOC and high calcium), the Ottawa River (medium DOC and calcium) as well as two lakes in Nova Scotia. The concentration sufficient to kill half the population of Daphnia magna after 48h of exposure (LC50), and the inhibition of cell growth of S. capricornutum after 72 h of exposure (IC50) were used to determine the sensitivity of these species to copper or nickel toxicity in these 5 water samples. In Part 3, I showed that the protection against copper or nickel toxicity was reduced with UVB radiation even though the total DOC was reduced by only 18%. The role of EDTA in the toxicity of copper and nickel on S. capricornutum was investigated in part 4. (Abstract shortened by UMI.)