Abstract
The macrobenthos and meiobenthos communities at five stations in Hiroshima Bay were investigated by simultaneous sampling over the couse of a year (1998) to estimate the production of their major animal groups. Polychaeta was the most abundant animal group of the macrobenthos throughout the investigation. Mollusca, consisting mainly of Theora fragilis, was the second most abundant animal group, and their density increased from April to July. Nematoda was the dominant animal group of the meiobenthos, comprising more than 75% of the total abundance of meiobenthos at all stations throughout the investigation except for St. 1 in March. Although the abundances of macrobenthos and meiobenthos varied overtime, the average abundances of macrobenthos as well as meiobenthos were highest at the innermost station in Hiroshima Bay. The mean biomass of macrobenthos in Hiroshima Bay was 3.26 g dry weight/m2, and that of meiobenthos was 0.49 g dry weight/m2. The production calculated from these values in biomass was 9.79 g dry weight/m2/year for macrobenthos and 4.93 g dry weight/m2/year for meiobenthos. These results indicate that the production of meiobenthos relative to that of macrobenthos is high in this eutrophic area.
