Features of the spatial distribution of the Japanese mud shrimp Upogebia major (De Haan, 1841) (Decapoda: Upogebiidae) in the Vostok Bay, Sea of Japan

In the estuary of the Volchanka River, Vostok Bay, Sea of Japan, the Japanese mud shrimp Upogebia major forms a population in the upper sublittoral zone at depths of 0.5-3 m in slightly silted sand. This population covers both open coastal bottom areas and a belt of the eelgrass Zostera marina, which is oriented parallel to the shoreline. The population density and biomass of the mud shrimp, as estimated by the abundance of holes on the ground surface, averaged 5.3 +/- 4.6 ind./m(2) and 36.46 +/- 16.74 g/m(2), respectively, and those calculated from the total sampling at counting sites were 4.2 +/- 2.6 ind./m(2) and 28.90 +/- 17.89 g/m(2), respectively. The biomass of the macrozoobenthos, which consisted of nine taxa, reached 87 g/m(2). Bivalves dominated in the community by biomass and slightly surpassed crustaceans, among which U. major dominated (33.2-41.9% of the total biomass of the macrozoobenthos).