SENSITIVE ACUTE TOXICITY TESTING IN TWO MARINE SHRIMP SPECIES: COLLECTION AND REARING OF LARVAE, AND CHANGES OF ACUTE TOXICITY VALUES DURING LARVAL DEVELOPMENT

摘要

Many toxicity data are necessary to precisely evaluate the ecological risk of hazardous chemicals. Data on toxici-ties to the early life stages of marine organisms are especially needed to elucidate the impacts of chemicals on the reproduction of those organisms, due to their highest sensitivity among growth stages. Therefore, we investigated the collection and rearing of larvae of two shrimps (Hepta-carpus futilirostris and Palaemon serrifer), their starvation resistance, and changes of their sensitivity on acute toxicity of chemicals during development of larvae, and we propose a sensitive acute toxicity testing method for larvae of these shrimps. The larvae of H. futilirostris have higher sensitivities than other crustaceans to tributyltin chloride (TBTCl), whereas the acute toxicity of TBTCl to P. serrifer and of hexavalent chromium Cr(VI) to both species was intermediate, compared with that to other crustaceans. The acute toxicities to larvae of these species were higher than those to juveniles. However, obvious differences in toxicities to larvae were not recognized among developmental stages (0-, 1-, and 5-day-old larvae) in P. serrifer. Heptacarpus futilirostris had higher sensitivity to TBTC1 and Cr(VI) than P. serrifer, and difference of their sensitivities on chemicals was especially marked when immobilization was used as the end-point. Zero-day-old P. serrifer larvae molted during the acute toxicity test, and sensitivity of the molted individuals notably increased. The 0-day-old larvae constituted a population at a uniform developmental stage; therefore, the use of 0-day-old larvae of H. futilirostris and P. serrifer is recommended for acute toxicity testing of early-life-stage crustaceans. Forty-eight-hour acute toxicity testing can be successfully performed in 0-day-old larvae of the two species, because 0-day-old larvae can survive normally for 48 h without feeding. Methods for collection and rearing of the larvae are also described.