| Budget Amount *help |
¥15,000,000 (Direct Cost: ¥15,000,000)
Fiscal Year 2002: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 2001: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2000: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1999: ¥6,000,000 (Direct Cost: ¥6,000,000)
|
|---|
| Research Abstract |
In the non-coral reef area, Amakusa, the lowest seawater temperatures in February were gradually coming up in these past 50 years. Seaweed beds were gradually decreasing in their habitats and corals and fishes associating coral reefs, so called "tropical" of "subtropical" components, were conversely increasing in the empty underwater-rock reefs especially after 1995.
After the world-wide events of coral bleaching in 1998, about 90% of living corals disappeared in the coral reefs around Okinawa Main Island. As to Sesoko I., settlement of juvenile corals is much less than that before the coral bleaching event. Juvenile corals safely settled were also died within a few years by the attack of crown-of-thorns starfish (Acanthaster planci). It seems hardly to recover the population of corals, especially in Acropora species. In Kerama Islands as a resource of coral larvae, mortality rates of corals, which had not suffer the coral bleaching events, are so high because of the predation by A. pla
… More
nci, and it seems also emergent conditions still now. While, in Sekisei Lagoon where most of corals survived through the coral bleaching event in 1998, another coral bleaching event was observed in 2001 and 10-20% of Acropora species died. Because of the effect of global worming, the seawater temperature in Sekisei Lagoon frequently reached to 30℃ in summer, the coral bleaching becomes into "common event". Perhaps, because of the severe effects by the coral bleaching, the photosynthetic activity of zooxanthella is lower than normal and the growth rate is lower than that in Amakusa and is only the half of the growth rate in ten years ago. The settlement of juvenile corals is also lower in Sekisei Lagoon than the density of juvenile corals in Sesoko I. Before 1998. A. planci was also observed in the lagoon after 2002, it will be anxious about the "outbreak" of the sea star. There is a fear that the living corals in these reefs will disappear in the near future, if there is no improve in the present conditions.
A ceramic instrument was developed based on former results of researches for recovering coral reefs destroyed. The preliminary experiments using the ceramics could obtain good and expected results. We are intending to evaluate and revise the ceramics from several viewpoints for establishing the effective method to recover the coral community and coral reefs. Less
|
