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The fiddler crab, Austruca lactea inhabits tidal flat areas and is widely distributed across Japan, the Korean Peninsula, China, Taiwan and northern Vietnam. Fiddler crab habitat is being lost rapidly due to human impacts and this species is currently listed as endangered in Japan. We studied the population genetic structure of A. lactea using mitochondrial DNA control region markers to define management units. A. lactea individuals were sampled from Osaka, Hiroshima and Kumamoto in Japan, and from Taichung and the Penghu Islands in Taiwan. All local samples exhibited high levels of genetic diversity, and no sampled populations showed evidence for a significant decline in effective population size that can result from population bottleneck effects. Pairwise FST estimates distinguished three discrete A. lactea populations corresponding with, the Seto Inland Sea (Osaka and Hiroshima), Kyushu (Kumamoto) and Taiwan. The three populations showed clear differences in historical population expansion times and their population dynamics after expansion. Results of the study indicate that A. lactea dispersal is limited geographically and that high levels of genetic diversity are maintained both within and among populations., 論文

To estimate the relative importance of mangrove swamps for sesarmids habitat, total\norganic carbon (TOC) and inorganic nutrients in water, and the sediment C/N ratios were\ndetermined from three different sites of the Ryukyu Islands: the Shira River mangrove\nswamp at Iriomote Island, the Nuha River mangrove swamp at Okinawa Main Island, and\nthe Nagura River mangrove swamp at Ishigaki Island, during December 2000, August 2001,\nand September 2002, respectively. The concentrations of total organic carbon in mangrove waters were 1.28, 1.52 and 0.60 ppm in the Shira, Nuha and Nagura rivers, respectively. The concentration of inorganic nutrients were determined from those mangrove waters are sodium (Na^+), potassium (K^+), ammonium (NH^+_4), chlorine (Cl^-), fluorine (F^-), bromine (Br^-), nitrate (NO^-_3), phosphate (PO^-2_4) and sulfate (SO^-2_4). No satisfactory explanation was found for the high concentrations of sodium and chlorine. The mangrove sediments C/N ratios were 17.9, 12.8 and 25.2 in the Shira, Nuha and Nagura rivers, respectively. The C/N ratio of Nuha river sediment was lower than that of the Shira and Nagura river, indicating higher nutritional value because of many organic matters decomposed here. Sediments from three mangroves had a mean C/N ratio of 18.6, indicating lower C/N ratios could be a richer source of nitrogen, which is regular ingestion by sesarmid crabs. Significant differences (P, 紀要論文

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A marked zonation pattern was recognized on the rocky intertidal along the coast of Dinard, Brittany, France. Patella spp., Gibbula spp. and balanoid barnacles showed a habitat segregation in terms of vertical distribution. The community structure of small animals associated with various sized patches of Mytilus edulis (“Mytilus islands”) was analyzed at two tidal levels and differences in the species composition were found. At both levels, the species richness and number of individuals increased with patch size, but the species density (number of species/patch area) decreased. On the other hand, the absolute density (number of individuals/patch area) was relatively constant irrespective of patch size. This was due to the great abundance of small barnacles such as Chthamalus monlagui, Balanus balanoides and Elminius modestus, which were attached to the Mytilus shells, and the small bivalve Lasaea rubra. Species diversity (H') did not show any trend with patch size, but equitability (J') decreased. The importance of micro spatial characteristics in discussion of species diversity is emphasized., 紀要論文

琉球大学21世紀COEプログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成20年度成果発表会（平成21年3月14日開催） 講演・特別講演会場：理系複号棟102号室，ポスター発表会場：琉球大学50周年記念館1F

琉球大学21世紀COEプログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成20年度成果発表会（平成21年3月14日開催） 講演・特別講演会場：理系複号棟102号室，ポスター発表会場：琉球大学50周年記念館1F

琉球大学21世紀COEプログラム「サンゴ礁島嶼系の生物多様性の総合解析」平成20年度成果発表会（平成21年3月14日開催） 講演・特別講演会場：理系複号棟102号室，ポスター発表会場：琉球大学50周年記念館1F