| Budget Amount *help |
¥4,080,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2007: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Fiscal Year 2006: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
1. Distribution and abundance of pattotfishes (Scaridae) were investigated on the coral reefs of Iriomote Island, Tokashiki Island, and Sesoko Island, Okinawa. Spawning site was found only on the fringing reef of Iriomote Island where parrotfish were most abundant among the three locations. Observations on their feeding behavior revealed that most of them bit dead coral skeleton to take filamentous algae but did not bite live corals.
2. Spawning of 13 species of parrotfishes was observed at a projection of the reef edge on the north coast of Iriomote Island. Spawning time differed among species: parrotfishes that migrated a long way (ca.500m) to inshore feeding sites tended to spawn only in the early morning (0630-0830hurs), while species that foraged near the reef edge usually spawned at high tide. By contrast, surgeonfish (Acanthuridae), another herbivorous fish, usually spawned at dusk at the same reef edge. Further investigation is now in progress to reveal the reason why spawning time differed among the herbivorous pelagic spawners.
3. Effects of algae and herbivorous fishes on survival and growth of small coral colonies were examined by caging experiments on the reef flat of Iriomote Island. The results suggested that not only parrotfishes but also surgeonfishes affected on the growth and survival of small coral colonies at the study site.
4. Effects of bites on live coral colonies, probably by fishes, were investigated on the fringing reefs of Iriomote Island and Sesoko Island. The growth rate of small branching corals, Acropora spp., decreased when their tips were bit. On the other hand, the growth rate of massive corals, Porites spp., did not differ whether they had many teeth marks or not.
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