Acute and Subchronic Toxicity of Tributyltin Chloride (TBTCl) to the Marine Harpacticoid Copepod Tigriopus japonicus Mori

Abstract

Acute and subchronic toxicity experiments of tributyltin chloride (TBTCl) were conducted with the marine harpacticoid copepod Tigriopus japonicus. The 48-hr LC₅₀ and highest non-lethal concentration (NOLC) for adult females were 0.96 and 0.14 μg/L, respectively, whereas these values for adult males were 0.58 and 0.07 μg/L, respectively. For the mean cumulative number of nauplii produced per female, the 14-day highest no observed effect concentration (NOEC), lowest observed effect concentration (LOEC) and EC₅₀ were 0.025, 0.05 and 0.055 μg/L, respectively. The acute-subchronic ratio, i.e. the ratio of the 48-hr LC₅₀ for adult females to the 14-day highest NOEC, MATC (maximum acceptable toxicant concentration) and LOEC, was 38.5, 27.2 and 19.3, respectively. These results suggest that the concentrations of current ambient TBT (tributyltin) compounds in Japanese coastal waters can be assumed as the safety range for the survival, but are unlikely to cause a reduction in the number of nauplii produced per female of T. japonicus. The high concentrations in seawaters, sediments and/or seawaters released from sediments that have been observed in estuarine and coastal waters in Japan may lead to a considerable reduction of survival and numbers of nauplii produced by females for T. japonicus.