Establishment and maintenance of coral communities on sandy-muddy bottom: Studies based on "Inhabitation-chain hypothesis"

本研究研究了岛内岛Amitori湾、冲绳岛Oura湾和Kin湾砂泥底珊瑚群落的建立和维持机制。在Amitori湾，珊瑚群落沿着海湾口到海湾底的环境梯度变化。在泥泞的底部，分枝Acropora， Anacropora和Millepora丰富。在这些珊瑚的内部和周围，有许多碎片。较大的碎片比较小的碎片存活得更好。碎片化似乎对斑块的扩展和新地点的殖民化很重要。在这些珊瑚的骨骼碎片上，我们发现了许多附着的珊瑚种类。各种珊瑚的附着基质的提供和浮藻的沉降对珊瑚群落的建立和维持以及多物种在这些栖息地的共存至关重要。在冲绳岛的欧拉湾，赤腹油螺通过在成年蜗牛的壳中定居，将其分布范围扩大到泥底。在金湾沙底，独居珊瑚Heterocyathus和Heteropsammia通过与sipunculan Aspidosiphon的栖息共生建立了高密度种群。

We studied mechanisms of establishment and maintenance of coral communities on sandy-muddy bottoms, in Amitori Bay of Iriomote Island, Oura Bay and Kin Bay of Okinawa island.In Amitori Bay, coral communities changed along the environmental gradient from bay mouth to bay bottom. On the mudy bottom, branching Acropora, Anacropora and Millepora were abundant. In and around patches of these corals, there were many fragments. The larger fragments survived better than smaller ones. Fragmentation seems important for extension of the patch and colonization of new site. On the skeletal debries of these corals, we found many attaching coral species. Provision of attachment substrate and settlement of planulae of various corals seem important for establishment and maintenance of coral communities and multi-species coexistence in such habitat.In Oura Bay of Okinawa Island, Oulastrea crispata expanded its distribution range to muddy bottom by colonizing shells of adult Strombus snail. On the sandy bottom in Kin Bay, solitary corals Heterocyathus and Heteropsammia established high density populations by inhabitation-symbiosis with a sipunculan Aspidosiphon.