The summer invertebrate fauna in and around the eelgrass beds in Koajiro Bay and Moroiso Bay, Miura Peninsula, central Japan
Physiology and Ecology Japan 31(1-2): 21-38
Invertebrate assemblages in and around the eelgrass beds of Koajiro and Moroiso bays, Miura Peninsula were examined in the summer of 1990. Various sampling methods including a dip net, a seine, a gill net, SCUBA diving with a dip net (or with bare hands), trap bottles, trap baskets, or by a fish lamp with a dip net were used to obtain a wide variety of animals with various mode of life. Additional samplings were made for the infauna, phytal animals and zooplankton by a double quadrat with a net bag and a submersible pump, a cloth bag and vertical hauls of a plankton net respectively. The invertebrates collected by the respective devices were reported with reference to their habitat and notes on the marked differences between assemblages in Koajiro and Moroiso bays. Not a few differences were attributable to the physical environment specific to the respective eelgrass beds such as the embayment degree, existence of immediate influx of flesh water, or the properties of substratum, principally based on the existence of the well established characteristic species. Some accounts for the validity of or perspectives on the use of the collected invertebrates as the indicators of inshore water environments were also given. Special attentions were paid to the availability of epitokal breeding swarms of Errantia polychaetes and zooplankton gathering around a fish lamp for environmental studies in relation to the sampling efficiency and the accessibility to the effect on life history traits such as reproduction and recruitment. Some phytal animals were also included in the attractives in environmental studies in relation to the accessibility to quantitative analysis of the effect on life history traits such as reproductive success with simple sampling.