Effects of Cu+2 and pH on the fitness of Ceriodaphnia dubia (Richard 1894) (Crustacea, Cladocera) in microcosm experiments.
An important disturbance of anthropogenic origin frequently occurring in freshwater ecosystems is a rise in the concentration of heavy metals in solution, among which copper stands out due to its known toxicity. However, the study of the chemical behavior of copper in solution is highly dependent on pH. In this study, the effect of ionic copper on the fitness of Ceriodaphnia dubia was assessed in microcosm experiments under different conditions of Cu+2 and pH. Two groups of experiments were conducted: effects on survival and fecundity, and effects on population dynamics. In the former, both pH and copper concentrations were manipulated. On the other hand, only the concentration of biologically available ionic copper was manipulated whereas pH was maintained constant in the population dynamics experiments. There was an agreement between both sets of experiments in terms of their results, showing important toxic effects of copper as evidenced through significant differences between controls and treatments in survival and fecundity. Mean age of first reproduction was delayed, and both the number of neonates produced per female and number of broods decreased with the increase in the concentration of copper. R0 was always lower at pH 6 than at pH 8 and was negatively related to the increment in the concentration of copper under either pH. A significant effect on population dynamics at 5 micrograms l-1 of copper sulfate was found and the extinction of the population at 20 micrograms l-1 of copper sulfate. New values of toxicity from copper are proposed, and the potential effects that an increment in copper could have on the communities that occupy a central position in aquatic food webs are discussed.
Gagneten
A M
AM
Facultad de Humanidades y Ciencias, Universidad Nacional del Litoral, Ciudad Universitaria, Paraje El Pozo, (3000) Santa Fe, Argentina. amgagnet@fhuc.unl.edu.ar
Vila
I
I
D000818:Animals; D003300:Copper / Q000009:adverse effects*; D003445:Crustacea; D005260:Female; D005298:Fertility / Q000187:drug effects*; D020387:Food Chain; D006863:Hydrogen-Ion Concentration; D011157:Population Dynamics; D012995:Solubility; D016019:Survival Analysis; D014873:Water Pollutants / Q000009:adverse effects*
D014873:Water Pollutants; D003300:Copper