Field metal mixture toxicity: linking freshwater biota species diversity to chemical speciation and bioavailability

Understanding metal and proton toxicity under field conditions requires consideration of the complex nature of chemicals in mixtures. We have previously demonstrated a novel method that relates streamwater concentrations of cationic metallic species and protons to a field ecological index of biodiversity (EPT species richness). The model (WHAM-FTOX) has also been used to assess regional temporal trends involving comparison of modelling and observations. This presentation communicates a new application of this model to lake zooplankton species richness. The field indicator used in this work was the combined richness of Cladocera and Copepoda zooplankton species. The new modelling has been undertaken with over 1000 data from surveys of 185 individual lakes in 7 different geographic regions. We present data for general model fitting and details from individual regions, including temporal trends.