Interactive effects of copper and calcium in Daphnia pulex

摘要: Many freshwater habitats around the world suffered dramatic water chemistry changes over last century mostly due to anthropogenic activities, including an overall reduction in pH high sulfur emissions and unsustainable forestry practices. One consequence of this change is a drop available calcium concentration, which creates problems for aquatic organisms that rely on dissolved build their exo- or endoskeletons reinforce carapace during regular molts. Daphnia populations shield lakes northern Ontario are also exposed other stressors, copper, persists at concentrations many these ponds mining human activities. Copper toxicity animals influenced by availability competing ions, such as calcium. Using our newly developed throughput screening system, we show mortality pulex increases with exposure low (0.05 mg L -1 ) copper (300 µg ). When two stressors were combined, found was less toxic concentrations, indicating protective effect against toxicity. We then established basic uptake kinetics D. using radioactive tracer 45 Ca provide evidence environmentally relevant competes based K m V max . Our data both decline increase ecosystems may negatively impact natural populations, interactions between metals occur environments result fitness consequences zooplankton.