Degradation mechanism on coastal ecosystems in shallow water as open multi-coupling systems and their conservation strategy

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1) Conducting field surveys in the fringing reef of the east coast of Ishigaki Island, we found characteristic features of advective diffusion process of red-silt and spatio-temporal variations of nutrients and phytoplankton. 2) Based on the results of field surveys and numerical simulations for the Shiraho reef of Ishigaki Island, we found the formation mechanism of coral slicks around the reef, and the release timing and density distributions in the water column of blue coral (Heliopora coerulea) larvae and their dependence on the tidal phase. 3) We developed a numerical 3-D current model incorporated with a coral canopy layer model and thereby found that the coral larvae may retain longer in the reef when released around neap tide. 4) We conducted long-term continuous measurements of terrestrial environmental loads from the Todoroki watershed adjacent to the above mentioned reef and developed a basic model for evaluating the land-based environmental discharge. 5) Developing microsat … More ellite markers and conducting genetic population analyses of crown-of-thorns starfish specimens taken from 23 sites in the Indo-Pacific regions including the Ryukyu Islands, we found that the gene flows are strongly governed by the magnitude of the ocean currents in the area concerned. With the numerical simulations of larval dispersal around the Kuroshio area, we reproduced the asymmetrical dispersal process along the area covering the Philippines, the Ryukyu Islands, Kyushu, Shikoku and Kii Peninsula, and clarified also with genetic population analyses that the Kuroshio may induce the secondary outbreaks. 6) We have indicated that coral cores may provide environmental fluctuation information over the past thousands years with the time resolution of 100 years, mangrove clay cores may provide information over the past 100 years with several years resolution, and coral annual rings may provide information of environments and terrestrial runoff in the past 100 years with 1 month resolution. Less