| Co-Investigator(Kenkyū-buntansha) |
TANABE Shinsuke Ehime University, Center for Maarine Environmental Studies, Professor, 沿岸環境科学研究センター, 教授 (60116952)
OHTA Suguru The University of Tokuo, Ocean Research Institute, Professor, 海洋研究所, 教授 (10013591)
NISHIKAWA Jun The University of Tokyo, Ocean Research Institute, Research Associate, 海洋研究所, 助手 (10282732)
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| Research Abstract |
To assess the present status of the impact of anthropogenic pollutants on deep-sea ecosystems, investigations were made in the marginal seas of Southeast Asia, the equatorial Pacific, and Sagami Bay, central Japan, and levels of pollutants were analyzed for various ecosystem components, including pelagic- and benthic organisms, marine snow, and bottom sediments with special reference to the ecological properties of the organisms, such as their vertical distributions and trophic levels. The analysis of organotin compunds, organochlorines and polybrominated diphenyl ethers in the Sulu Sea revealed, for the first time, that these compounds are accumulated in the deep-sea animals in the area, while their levels are lower than in the other, more northern areas of the western Pacific. In Sagami Bay, organotin compounds were detected from all deep-sea animals that were analyzed, including mesopelagic micronekton, benthic invertebrates and demersal fishes. The analysis of trace elements and stable-isotope ratios indicated positive correlations of of δ^<15>N with such elements as Hg, Sn, Cs, but negative correlations with others such as Cu, Mo, Ba, indicating different trends of accumulation between organisms of different taxonomic positions and with different physiological/ecological properties. Concurrent investigations on the vertical structure of pelagic assemblages suggested importance of herbivorous copepods, the copepods that feed on marine snow, and fish- and decapod micronekton that perform marked diel vertical migration in the active transport of the pollutants. An analysis of stable-isotope ratios suggested another pathway by which pollutants adsorbed on marine snow derived from surface phytoplankton quickly sink to the bottom to be incorporated into the benthic communities.
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