2004 Fiscal Year Final Research Report Summary
Study on relation between marked decline of bivalve resources and environmental pollutants in Ariake Sea, Japan
| Project/Area Number |
14360112
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General fisheries
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
HONJO Tsuneo Kyushu University, Graduate School of Bioresouce and Bioenvironmental Sciences, Professor, 大学院・農学研究院, 教授 (80284553)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMADA Hideaki Kumamoto University, Faculty of Education, Assiciate Professor, 教育学部, 助教授 (40226212)
OSHIMA Yuji Kumamoto University, Faculty of Education, Assiciate Professor, 大学院・農学研究院, 助教授 (70176874)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Ariake Sea / Bivalve / Chemical / Pollution |
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| Research Abstract |
We investigated anthropogenic chemical pollution in the Ariake Sea, and evaluated the reproductive effects of tributyltin (TBT) on bivalves. Our studies suggested that the decrease in the biomass of bivalves in the Ariake Sea might be attributable to chemical contamination.
1)Pollution in the Ariake Sea : the Ariake Sea is a very important bivalve habitat ; however, TBT concentrations in short-necked clams ranged from 0.062 to 0.125 μg/g in 1998 and from 0.008 to 0.033 μg/g in 2001. Further, concentrations of TBT in pen shells collected from the Ariake Sea in 2001 ranged from 0.009-0.095 μg/g. These results clearly demonstrate that TBT contamination of bivalve is still occurring in the Ariake Sea even after regulation of TBT usage. Concentrations of heavy metals (Hg,Cu,Cd) were at normal levels. However, 12 of 562 agrichemicals investigated were detected in samples collected in Aug. 2003 from the Chikugo River that flows into the Ariake Sea. Thus, there is concern that a mixture of these chemicals will adversely affect on organisms in the Ariake Sea.
2)Reproductive test of bivalves : We examined the reproductive effects of TBT on the pearl oyster (Pinctada fucata martensii) and the short-necked clam (Ruditapes philippinarum). In pearl oysters, successful embryo developmental was significantly decreased at a concentration of 0.088 μg TBT/g in the ovary. In short-necked clams, a 20% effective concentration of TBT on embryo developmental success (EC20) for the female clam was 0.099 μg TBT/g. These results strongly suggest that TBT pollution might inhibit reproduction of bivalves in the wild.
We developed epiphytic diatom (Cylindrotheca closterium)-a free living marine nematode (Prochromadorella sp.1) bioassay system and exposed TBT against this system. As a result, a slight growth inhibition of nematodes was observed at 3.26 μg/L ; both organisms in the bioassay system were dead at 32.6 μg /L.
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