Residues of endosulfan in carp as an indicator of exposure conditions.

: Endosulfan is an organochlorine insecticide, consisting of a mixture of two isomers: alpha and beta endosulfan. Endosulfan residues were determined in livers and gills of carp exposed to lethal and sublethal concentrations of endosulfan. The fish which were exposed to a lethal concentration contained the highest residue level in both liver and gills. In carp liver, the percentage of beta endosulfan in the residue decreased with time between exposure and collection of samples whereas the percentage of endosulfan sulphate increased. Carp killed by exposure to endosulfan had a significantly greater ratio of beta to alpha endosulfan and a significantly greater percentage of beta endosulfan in their livers. There was no such clear relationship for the residue composition in fish gills. The determination of residue composition, in particular the percentage of beta endosulfan or the ratio of beta to alpha isomers is recommended in investigations of fish kills when endosulfan is a suspected cause.

Use of Australian cladocerans to generate life-cycle toxicity data.

Cladocerans (or water-fleas) are important animals in freshwater exosystems. They are widely used in toxicity tests because of their small size, ease of culture, and sensitivity to chemicals. They are particularly suited to life-cycle tests because newly-hatched young can produce offspring in less than one week. Most data are available for European and North American species, and may be not be appropriate to Australian conditions. In the present study, eight Australian cladocerans were evaluated in three-brood life-cycle tests over ten days or less. Species were evaluated by duration of life cycle, ease of handling, numbers of young produced in three broods, and stability in laboratory culture.Ceriodaphnia cfdubia was the best test species. The greatest number of young, the highest survival rate and the shortest time to produce three broods were achieved in filtered Sydney mains water, aged in the presence of fish, using blended trout pellets and alfalfa as food.