Characteristics of butyltin accumulation and its biomagnification in steller sea lion (Eumetopias jubatus)

Abstract

The present study was conducted to examine sex difference, age, and temporal trends of butyltin accumulation and its biomagnification in Steller sea lion (Eumetopias jubatus) collected from Alaska, USA, during 1976-1985 and from Hokkaido, Japan, during 1994 Average concentration of total butyltin compounds (⌺BTs) in the liver of Steller sea lion from Alaska (19 ng/g wet weight) was much lower than those from western and eastern Hokkaido, Japan (150 and 220 ng/g), respectively. This result suggests that Japanese coastal waters are contaminated with BTs in comparison with those of Alaska. In most samples, dibutyltin (DBT) residues were retained at higher levels than tributyltin (TBT), suggesting the degradation of TBT to DBT in the liver. Sex difference and age-dependent accumulation of BTs residues were not found in Steller sea lion. Similarly, no prominent temporal trend in BT concentrations was observed between 1976 and 1985. Nevertheless, the annual consumption of organotin compound was doubled in the United States during the same period. These results suggest that the butyltin compounds are degraded faster than the intake from diet in Steller sea lion. The biomagnification factor of BTs in Steller sea lion was low (0.15-4.6; mean, 0.6), indicating that this animal is unlikely to magnify BTs due to rapid degradation and excretion.

Accumulation of butyltin compounds in dolphins stranded along the Mediterranean coasts

“…However, the high coefficient of variation of the data (CV = 95% for liver, n = 8; and 91% for kidney, n = 7) did not enable any significant difference in the residue pattern of BT Appl. Although the number of samples was too small to discern any sex-related variations, this result appears to be in line with previous studies on Risso's dolphin, 24 the Steller sea lion 17 and harbour porpoise. Chem.…”

“…16 Various studies have shown that TBT accumulates in aquatic organisms, mainly those at lower trophic levels in the food web (e.g. 24,25 These studies have shown that TBT accumulates and is biomagnified by marine mammals, irrespective of sex; accumulation is generally greater in early life and the liver appears to be the organ where the highest concentrations are found. Many recent studies have focused on tissue concentrations and distribution of TBT and its metabolites in marine mammals.…”

Butyltin Compounds in River Otters (Lutra canadensis) from the Northwestern United States

“…Moreover, furbearing animals such as river otters may eliminate butyltin compounds during their annual molting cycle since butyltins have a tendency to bind to structural proteins in fur and hair. Elimination of butyltin compounds by molting has been reported in Stellar sea lion, a fur-bearing marine mammal (Kim et al 1996b). In any case, our results suggest the accumulation of butyltin compounds in river otters from inland rivers.…”

“…For a complete assessment of the impact of butyltin compounds in aquatic ecosystems, it is necessary to examine the accumulation and effects of these compounds in various organisms in the food chain. Our recent studies have shown that butyltin compounds accumulate in body tissues of marine mammals and water birds at significant concentrations, and that butyltin contamination in higher trophic level animals in the food chain is widespread (Iwata et al 1995;Kannan et al 1996Kannan et al , 1997aKannan et al , 1998Kannan and Falandysz 1997;Kim et al 1996aKim et al , 1996bGuruge et al 1996;Tanabe et al 1998).…”

Ecotoxicological effects at contaminated sites

“…Marine gastropods and oysters are among the most susceptible organisms, but fish are affected as well, although at concentrations of 1-10 g/L. However, the long-term ecotoxicological effects of organotins on the structure and function of aquatic ecosystems are still not well understood, particularly with respect to biomagnification in food webs (Guruge et al, 1996;Jak et al, 1998;Kannan et al, 1996;Kim et al, 1996;Stäb et al, 1996).…”