Towards the Wise Use of Coral Sea: Biological and Social Scientific Research about Optimal Use ＆ Resource Management of Marine Environmental Resources

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1. Our research aims to study actual human impacts, e.g. by economic activity in land area, or by leisure diving, on coral community and the related ecosystem, and implementing social/economic/legal mechanism that make sustainable use of marine natural resources possible. To achieve these goals, we chose 2 main fields : one is the Kashiwajima Island in the Kochi Prefecture where conflicts and overuse in coral sea are at issue, the other is the Yoron Island in the Amami Archipelago that is suffering from serious coral bleaching events. 2. The Yoron Is. : Local residents started Um (= coral) project to promote the restoration of coral. The results of the surveys for supporting this are as follows: (1) Ecological survey: Northwest coral reef was covered at about 50% by living corals. Newly settled juvenile corals were very few except for here where 71 species were recognized. The amount of settlement in 2007 was 107 juveniles on 140 plates (10cm square) and was not so much. Most of juveni … More le corals are Porites, subordinately genus Acropora and Pocilloporidae. Highest density of newly settlement was observed at the northwest reef and it was very rare at other outer-reefs. Ceramics for settlement of coral larvae was also set at the northwest reef and juveniles settled about 17 % of the ceramics. These show a possibility of recovering living corals by the ceramic transplantation in the reef. (2) Water quality survey : As results, in some sampling sites, DIN and DIP concentrations were often over 10-20 μm and 1-2 μM, respectively. These values are significantly high compared with other coral reef. The amounts of water volume flowing into the coastal areas were not so much, but these concentrations in inflow land waters were sometimes extremely high. It was suggested that inflow of highly eutrophic land water to the coastal environment would be possibly causative to the coral reef damage. (3) Legal study : The effect of Law Concerning the Appropriate Treatment and Production of Utilization of Livestock Manure, to correct inappropriate management of livestock manure, was not enough to protect the environment of a small island like Yoron. The government and the people made a unique standard about treatment and utilization of livestock manure and constructed the compost center. Yoron's challenge gives us the key to what policy can be enforceable to realize general protection and reproducing of coral reef. Next, there is the probability that eutrophicated groundwater outflow to sea and damage coral reef. Then about the possibility of regulating groundwater utilization, regulation of groundwater overdraft does not necessarily mean the taking of landownership, but just limiting the exercise of it, not only risk regulations (pollution control and prevention of land subsidence) but permit system of ground water extraction can be introduced through ordinances if it is proved that the regulations is necessary and there is no less restrictive alternatives. 3. The Kashiwajima Is.: It has been reported 884 fish species belonging to 143 families occurred by 1996. Such high fish diversity might have close relation with the development of hermatypic coral community. But the coral community was given severe damage by the increasing number of divers, corallivorous gastropods and frequent typhoon attacks. (1) Compared with the difference of fish fauna at the 2 experimental sites where coral community is present and absent, the fish individual numbers are significant different in chaetodontids, pomacanthids, pomacentrids, labrids, scarids and acanthurids. (2)The hermatypic coral community was destroyed by typhoons in 2003-4. In 2005, the rate of coverage was 1-3 %. The daily growth rate of young corals after typhoon attacks are 1.09% (Ushironohama), 0.48% (Ryunohama) a day. (3) By CVM and CB, we evaluated the benefits of biodiversity in this coral sea and analyzed factors determined WTP. 4. To conclude, we classified the factors of deteriorating coral sea by the difference of human involvements' pattern, and considered environmental means/policy to mitigate such deteriorations through the case studies. So I clarified that the key to wise use is held by the point whether local community/association of traditional/present sea user, represented by fishermen's group, take the initiative to make good order of utilizing coral sea. Less