Effects of Water-Borne Mirex on the Survival and Production of Macrobrachium Rosenbergii (De Man)

摘要

Water-borne mirex, in concentrations above 100 micrograms/l, was lethal to postlarval Macrobrachium rosenbergii in a 24-hour exposure acute toxicity experiment. Adult and juvenile prawns did not show a clear relationship between survival and concentration when exposed to mirex in water for 24 hours. Postlarvae exposed to mirex in water for 96 hours, with 10 prawns per test container, exhibited reduced survival with increasing mirex concentration. Individually exposed postlarvae (96 hours) did not exhibit such a distinct mortality pattern. A significant increase in length of molt intervals with increasing concentration was found for postlarvae individually exposed to mirex in water for 96 hours. Potential production figures, calculated from data for prawns individually exposed indicate an increase in production (wet weight) of controls 2.24 and 1.70 times that of prawns exposed to 100 and 10 micrograms/l, respectively. Mirex residues in the tested postlarvae generally increased with increasing mirex concentration. Residues of mirex in postlarvae exposed to mirex for 24 hours (no food was present during the exposure period) suggest that M. rosenbergii can absorb mirex from the surrounding water. Water samples showed a marked decrease in mirex residues after 96 hours.