Biomagnification Process of Total Mercury in the Macrobenthic Communities in an Enclosed Bay, Isahaya Bay, Kyushu, Japan

抄録

In the inner part of Isahaya Bay, Kyushu, western Japan, we assessed the biomaginification of total mercury (THg) in the benthic system. The sediment contained 133 ng/g d.w. of THg, which was about 4.9 times higher than particulate organic matter (POM) in the overlying water on the sediment. Both the primary and secondary consumers of the macro-benthic animals were divided into two groups in THg content, respectively. In the primary consumers, “High THg content group (101 ± 23 ng/g d.w.,mean ± S.D.)” consisted of animals that relied on the THg-contaminated sediment for diets and/or habitats. Its mean THg content was about 4.0 times higher than that of “Low THg content group” that occurred on the sediment surface or outside the sediment, and depended on diets suspended in the water. In the secondary consumers, “High THg content group (215 ± 47 ng/g d.w.)” were made up of crabs and sea star, which favored the animals (mainly clams) of “High THg content group” of the primary consumers for diets. Two different biomagnification pathways of THg existed in a single food chain of the macro-benthic communities.