ACUTE TOXICITY OF COPPER, CADMIUM AND ZINC TO 3 SPECIES OF MARINE COPEPOD

Acute toxicity tests were carried out with 3 metals on the marine copepods Scutellidium sp., Paracalanus parvus and Acartia simplex. The resulting 24 h LC50 values showed that Cu was the most toxic metal, with Cd more toxic than Zn for 2 of the 3 spp. Scutellidium sp. was more sensitive than P. parvus and A. simplex to all metals; LC50 values were 0.18, 0.66 and 1.09 mg/l for Cu, Cd and Zn, respectively. No consistent trend in relative sensitivity was apparent for the other 2 spp. The results were in general agreement with those for other marine copepods given by other workers. Some experimental problems in conducting toxicity tests with copepods are indicated. Application of the present LC50 data to existing water quality criteria produced unrealistic safe concentrations in the case of Cu. Such a finding illustrates the arbitrary nature of application factors and questions the usefulness of acute toxicity tests as the major tool for environmental protection.