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(T/MF185) Comparative sensitivity of laboratory-reared and field-collected organisms. Bossuyt, Bart1, Heijerick, Dagobert1, Janssen, Colin1, 1 ABSTRACT- In aquatic toxicology, most experiments are performed with artificial media and laboratory cultured organisms. Generally, standard test organisms should be ecologically relevant, ubiquitous for the aquatic environment and have a similar sensitivity compared to local species. In this study, we examined the comparative sensitivity of laboratory and local species exposed to copper in natural waters and in laboratory media. Daphnia magna and Raphidocelis subcapitata were used as laboratory-reared species and Scapholeberis mucronata, collected from pristine Swedish lakes, was used as field-collected test organisms. When using laboratory medium (M4), S. mucronata had a higher copper sensitivity than D. magna. A similar copper sensitivity of these two cladocerans was observed when using the three natural waters as dilution medium. The toxicity of copper to laboratory-reared R. subcapitata tested in laboratory medium (ISO) was significantly higher than that observed when using the natural waters. It can be concluded that no large differences in copper sensitivity between the laboratory-reared and field-collected crustaceans were observed. When data from laboratory experiments are extrapollated to the field situations, the differences in the physico-chemical characteristics, determining the bioavailable metal concentrations, have to be taken in account for assessing the metal toxicity in situ. Key words: acute toxicity, copper, Daphnia magna, Raphidocelis subcapitata |
