Measured copper toxicity to Cnesterodon decemmaculatus (Pisces: Poeciliidae) and predicted by biotic ligand model in pilcomayo river water: A step for a cross-fish-species extrapolation

In order to determine copper toxicity (lc50) to a local species (cnesterodon decemmaculatus) in the south american pilcomayo river water and evaluate a cross-fish-species extrapolation of biotic ligand model,a 96h acute copper toxicity test was performed. the dissolved copper concentrations tested were 0.05,0.19,0.39,0.61,0.73,1.01,and 1.42mg cu l -1. the 96h cu lc50 calculated was 0.655mg l -1 (0.823-0.488). 96-h cu lc50 predicted by blm for pimephales promelas was 0.722mg l -1. analysis of the inter-seasonal variation of the main water quality parameters indicates that a higher protective effect of calcium,magnesium,sodium,sulphate,and chloride is expected during the dry season. the very high load of total suspended solids in this river might be a key factor in determining copper distribution between solid and solution phases. a cross-fish-species extrapolation of copper blm is valid within the water quality parameters and experimental conditions of this toxicity test. © 2012 mara victoria casares et al.