Studies on feeding and reproductive ecology of parrotfishes, key species for recovery of corals

1.调查了日本冲绳西表岛、十敷岛和濑子岛珊瑚礁中鲷科鱼类的分布和丰度。产卵场仅在西表岛的边缘礁上发现，在这三个地点中，鹦嘴鱼最丰富。对它们摄食行为的观察显示，它们大多咬死珊瑚骨架以摄取丝状藻，而不咬活珊瑚.在西表岛北海岸礁缘的投影处观察到13种鹦嘴鱼的产卵。产卵时间不同的物种：鹦嘴鱼迁移了很长的路（约500米），近岸觅食地点往往只在清晨（0630- 0830 hurs）产卵，而觅食的珊瑚礁边缘附近的物种通常在涨潮时产卵。相比之下，另一种食草性鱼类（Acanthuridae）通常在黄昏时在同一个珊瑚礁边缘产卵。目前正在进一步研究草食性中上层产卵鱼产卵时间不同的原因。在西表岛礁滩进行了小型珊瑚的网箱实验，研究了藻类和草食性鱼类对小型珊瑚群体生存和生长的影响。结果表明，在研究地点，不仅鹦嘴鱼，而且外科鱼也影响小珊瑚群体的生长和存活.在西表岛和濑子岛的边缘礁上调查了可能是鱼类叮咬活珊瑚群落的影响。小分枝珊瑚，鹿角珊瑚，当他们的指尖被咬时，另一方面，大型珊瑚，滨珊瑚属，没有区别是否他们有很多牙印或没有。

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.