HAGIHARA Akio University of the Ryukyus, Faculty of Science, Professor (90126889)
IZAWA Masako University of the Ryukyus, Faculty of Science, Professor (10192478)
TOKUYAMA Akira University of the Ryukyus, Faculty of Science, Professor (50045001)
MAEKADO Akira University of the Ryukyus, Faculty of Law and Letters, Professor (60190287)
FUJITA Yoko University of the Ryukyus, Faculty of Law and Letters, Associate Professor (70315456)
Integrated analyses including ecosystem function, animal ecology, forest ecology, environmental chemistry, geology, environmental economy, and environmental philosophy were conducted to evaluate the function of island and coral reef ecosystems in Okinawa. Food sources of benthic animals were identified using biomarkers of fatty acid profiles of tissue, which accumulated characteristic sources in a habitat affected by human activities.
Habitat change and direct effects by human activities negatively affected the ecology and population trend of felid species, Iriomote cat. On the other hand, the Ryukyu flying-fox could extend their distribution by utilizing the urbanized environments.
A subtropical evergreen broadleaf forest in the northern part of Okinawa Island consisted of four architectural layers. The lower layers contained many species of smaller height High species diversity of the forest depended on the small trees in the lower layers. Therefore, it may be concluded that the conservation of the small trees in the lower layers, especially the bottom layer, is indispensable to maintain the high diversity of Okinawan evergreen broadleaf forests.
When a huge amount of red soil flows into the river water and seawater, pH of the solutions decreases, Al dissolves from the red soil and concentrations of Na, K, Ca and Mg decrease in the solutions and other chemical characteristics in the system were clarified.
Economic value of coral reef as natural breakwaters was estimated to be about \83,270,000,000 per year by Replacement Cost Method. A fact-finding research on some site for marine recreation showed that people who engage in marine leisure activities and tourists coming to Okinawa to join these recreations are highly oriented to environmental conservation, and they are willing to pay for protection of coral reefs. Also, geological aspects and philosophical aspects were useful for the discussion on the effect of human activities on coral reef and island ecosystems.