Acute and chronic toxicity of chromium and cadmium to the tropical cladoceran pseudosida ramosa and the implications for ecotoxicological studies.
In this study, the acute and chronic toxicity of the metals chromium and cadmium were tested against the tropical freshwater cladoceran Pseudosida ramosa. Acute tests showed that the 48-h LC50 of chromium was 29 μg L(-1) , while that of cadmium was 12 μg L(-1) . P. ramosa had a similar sensitivity to those of other cladoceran species cultured in the same conditions as in this study, or a higher sensitivity when water hardness was raised. Long-term chronic exposure of P. ramosa to chromium decreased maternal survival, fecundity, and fertility at a concentration of 10 μg L(-1) . For cadmium, reductions in the same endpoints were observed at a concentration of 3 μg L(-1) . Moreover, the degree of toxicity of the chromium and cadmium to P. ramosa after release of the first brood was similar to the result obtained after 21 days, using reproduction as the endpoint. Brazilian water bodies located near industrial areas already show concentrations of chromium and cadmium higher than levels causing acute and chronic toxicity to P. ramosa in our study. Many water quality criteria in tropical regions are based on ecotoxicological tests with non-native species and, consequently, this may lead to errors of interpretation when the permitted maximum levels of for each toxic substance are established. Therefore, we reinforce the idea of using native species to establish the maximum concentrations of toxic substances in water quality criteria, especially for metals, since their effects are related to water hardness, pH, and temperature specific to each region.
Post-Graduate Program of Ecology and Natural Resources, Department of Ecology and Evolutionary Biology, Federal University of São Carlos, Rodovia Washington Luis km 235, CEP 13565-905, São Carlos, SP, Brazil.
Emanuela Cristina
EC
Freitas
Odete
O
Rocha
D000818:Animals; D002104:Cadmium / Q000633:toxicity*; D002857:Chromium / Q000633:toxicity*; D033361:Cladocera / Q000187:drug effects*; D054750:Ecotoxicology / Q000379:methods*; D005260:Female; D005298:Fertility / Q000187:drug effects; D007928:Lethal Dose 50; D023382:Toxicity Tests, Acute / Q000379:methods; D036401:Toxicity Tests, Chronic / Q000379:methods; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D014874:Water Pollutants, Chemical; D002104:Cadmium; D002857:Chromium