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タイトル: Bioavailability and effects of tributyltin in the caprellid amphipod, Caprella danilevskii: A review
著者: Ohji, Madoka
Arai, Takaomi
Miyazaki, Nobuyuki
キーワード: tributyltin
amphipod
caprellid
acute toxicity
chlonic toxicity
metabolic capacity
sensitivity
sex ratio
survival rate
reproduction
発行日: 2003年3月28日
出版者: Otsuchi Marine Research Center, Ocean Research Institute, the University of Tokyo
掲載誌情報: Otsuchi Marine Science. No.28, 2003.3, pp. 14-30
抄録: In order to examine the biological effects of tributyltin (TBT), both acute and chronic tests were conducted using amphipod crustaceans. In acute test, five species of caprellids and three species of gammarids collected from Otsuchi Bay, Japan, which belong to a closely related ecological niche, were used for the exposure experiments at seven test concentrations (0, 0.001, 0.01, 0.1, 1, 10 and 100μg TBTC11^<-1>) for 48-h at 20℃. The 48-h LC_<50> values of the caprellids were 1.2-6.6μg1^<-1>, and these were significantly lower than those of the gammarids (17.8-23.1 μg1^<-1>). This suggests that caprellids are more sensitive to TBT than gammarids. Furthermore, in the comparison of the 48-h LC_<50> values for TBT among the various trophic level organisms determined in the previous studies, the caprellids belong to a sensitive group of organisms. The proportions of TBT and its derivatives, dibutyltin (DBT) and monobutyltin (MBT), were measured in the amphipods collected from the bay. In the caprellids, TBT was the predominant compound, accounting for 72% of the total butyltin which reflected the butyltin ratio in seawater, while in the gammarids, TBT's breakdown products (DBT and MBT) predominated, accounting for 75% of the total butyltin. This difference suggests that caprellids may have lower metabolic capacity to degrade TBT than gammarids. Therefore, the difference in sensitivity to TBT among the amphipods is might to be related to the species-specific capacity to metabolize TBT. In chronic test, TBT exposure at ambient water levels, the caprellid amphipod, Caprella danilevskii, was exposed to five levels (0, 10, 100, 1000 and lOOOOng1^<-1>) of TBT during the embryonic stage (five days). Although the female proportion was 36% of the total in the control, the female proportion changed dramatically in the hatched juvenile, i. e. the proportion of females was found to increase to 55.6% at lOng1^<-1>, 85.7% at 100ng1^<-1>, and 81.8% at 1000ng1^<-1>. All specimens died in 10000ng TBTC11^<-1> within five days after spawning due to the acute toxic concentration for the species. No significant differences were observed to occur in the sex proportion in response to the exposure after hatching (50 days) in a previous study. Sex disturbance might therefore be induced during the embryonic stage in the caprellid. Reproductive inhibitions such as brood loss and oogenesis inhibition occurred even at 10-100ng TBTC11^<-1> exposures in the short-term period in both parental females and their offspring females. The embryo survival rate in the offspring decreased drastically as the TBT concentrations increased, with the decrease being observed at TBT concentrations as low as 10ng1^<-1> (69%) during the five days. In parental females, the survival rate also decreased at more than 100ng TBTC11^<-1>, despite movement after five days into the no TBT-added seawater. Therefore, our data suggest that nanogram concentrations of TBT similar to those encountered in coastal waters around the developed countries can directly affect sex proportion, reproduction, and survival in the caprellid.
URI: http://hdl.handle.net/2261/5342
ISSN: 13448420
出現カテゴリ:Otsuchi Marine Science
Otsuchi Marine Science

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