Seasonal change of species composition, abundance, and reproduction of solitary entoprocts in Okinawa Island, the Ryukyu Archipelago, Japan

摘要

Monthly samplings of solitary entoprocts were carried out at Mizugama and Ginowan Fishery Port, Okinawa Island, the central Ryukyus, Japan from November 2000 to November 2001. We examined the entoproct populations on the glass slides that had been placed at the two sites for 2 months, and a total of 18,322 individuals of solitary entoprocts were recorded. They were Loxomitra mizugamaensis, L. ryukyuensis, L. tetraorganon, Loxosomella aloxiata, L. intragemmata, L. lecythifera, L. monocera, L. stomatophora, and Loxocorone allax. Our analyses indicate that (1) the abundance of solitary entoprocts in this region is high in summer and low in winter, (2) most species reproduce by budding all year round, and (3) sexual reproduction is restricted to a short period in summer (July or August).