Promotion of multi-species coexistence in the community on microatolls of massive coral Porites : a test of Inhabitation-chain hypothesis

1996年至1998年，在冲绳岛古达卡岛护城河的大型珊瑚岩微环礁上对群落进行了维持和促进多物种共存的机制研究。结果表明，随着微环礁的生长，微环礁顶部的面积不仅增大，而且由于水蛭等双壳类的生物侵蚀或棘海胆等海胆的放牧而变得更加不规则。根据藻类、珊瑚、蚓类等各种无根生物的栖息情况，群落的物种丰富度有所增加。各种生物对微生境的提供、创造和调节似乎诱导了新物种的定殖，从而促进了多物种共存。埋在珊瑚骨架里的蛭体树突瘤使珊瑚表面光滑，使珊瑚不易被鹦鹉鱼啃食。蚓类和宿主珊瑚之间的这种关系似乎在强大的捕食者的存在下得到了加强。1998年夏季，库达卡岛护城河发现了珊瑚白化现象，但那些部分白化的大量珊瑚在半年后全部恢复。

Mechanisms by which multi-species coexistence is maintained and promoted were studied for the communities developed on microatolls of massive coral Porites in the moat of Kudaka Island, Okinawa for 1996 to 1998. It was proved that with growth of the microatoll, the area of the top was not only enlarged but also became more irregular due to bioerosion by boring bivalves such as Tridacna or grazing by urchins such as Echinometra. According to the inhabitation of various sessile organisms including algae, corals, vermetids etc., species richness of the community increased. Provision, creation and conditioning of microhabitat by various organisms seemed to induce new species to colonize, thus promoted multispecies coexistence. Dendropoma, a vermatid buried in the coral skeleton make the coral surface smooth, which make the coral difficult to be grazed by parrot fish. This relation between vermetids and host coral seemed to have been strengthened coevolutionarily under the presence of strong predators. In the summer of 1998 , coral bleaching episode was recognized in the moat of Kudaka Island, but those massive corals which were partially bleached all recovered in a half year.