EFFECTS OF HALOGEN TOXICANTS ON SURVIVAL, FEEDING AND EGG-PRODUCTION OF THE ROTIFER BRACHIONUS-PLICATILIS

The toxicity of free chlorine and combined chlorine as chloramine to the rotifer Brachionus plicatilis at three exposure temperatures has been evaluated. Chloramine was more toxic to rotifers than the free halogen form with LC50 values for 30-min exposures at 20 °C of 0·35 mg l-1 applied chloramine and 1·20 mg l-1 applied free chlorine, 0·02 mg l-1 and 0·18 mg l-1 residual levels, respectively. The synergistic effect of temperature on the toxicity of both halogen forms was also noted. Rotifers surviving exposure to either halogen toxicant had significantly lower filtration rates and egg production rates than control animals. The reduced reproductive rates were not sustained by the second generation of rotifers and it appears that exposure to free chlorine or chloramine does not result in a permanent alteration in the reproductive potential of rotifer populations. © 1979.