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On the maintenance mechanisms of scleractinian coral community in a peripheral area.

周边地区石珊瑚群落的维持机制研究.

基本信息

批准号：
02640511
负责人：
NOJIMA Satoshi
金额：
$ 1.22万
依托单位：
Kumamoto University (1992)Kyushu University (1990-1991)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1992
项目状态：
已结题

项目摘要

In comparison with the coral communities of Sesoko Island of Okinawa (in coral reef area). some features of the coral communities in Amakusa have been made clear.1) In spite of the long coast line, suitable shallow area for coral growth is narrower than that of coral reef area. However in several areas in Amakusa, coverages of corals sometimes reached 75%, and were not so much differed from that of Okinawa. However, total number of eggs spawned in Amakusa was quite fewer than in okinawa. 2) Presumably for this reason, density of larval settlement in Amakusa was quite low, only 1/10000 of Sesoko Is. 3) Effect of grazer such as Echinometra seemed as a distinct mortality factor of young corals. Density of this grazer is lower in Amakusa than Sesoko. Consequently, the discrepancy of both areas decreased relatively and the density of young corals in Sesoko Is. reached only 5 times of that in Amakusa. 4) During the growing season, the growth rate of corals in Sesoko Is. was 1.5 times higher … More than in amakusa. If the 5 times density is continuously maintained, rapid increment of coverage is expected in Sesoko Is. However, such rapid change in coverage have been not reported. This fact shows that some powerful predators such as Acanthaster and other influential mortality factors cause the reduction in the density. However, such influential factors lowering the density were raltively rare in Amakusa. According to the general survey on the distribution of corals by manta-method carried out in 1990, feeding scars and colonies partially died were rare in Amakusa. 5) It reported that most of corals in Amakusa died during the severe cold wave of 1962/63 winter. Diameter of table type corals, such as Acropora soliataryensis, sometimes reaches up to 2 m in Amakusa. If annual growth rate of 9 mm in diameter, measured in the present study, continues for 30 years, the maximum size of table type corals now present agree with the above report. This fact shows that scleractinian corals in Amakusa are growing under good conditions after the cold wave. Size frequency data of A. solitaryensis showed a successive pattern from small to large size. This successive size structure suggests a continuous settlement of young colonies. 6) In Amakusa where there is no powerful predator, effective mortality factors seem to be low temperature in winter, high temperature in summer and wave action during typhoon season. Many borers associated with corals also seems to contribute this reduction of corals during typhoon. Less

与冲绳雪子岛（珊瑚礁区）的珊瑚群落比较。天草珊瑚群落的一些特征已经很清楚了。1)虽然海岸线较长，但适合珊瑚生长的浅水区比珊瑚礁区窄。然而，在天草的一些地区，珊瑚的覆盖率有时达到75%，与冲绳没有太大的不同。然而，天草产卵的总数量比冲绳少得多。2)可能是由于这个原因，天草的幼虫沉降密度很低，只有雪子岛的1/10000。3)食腐动物如棘足虫的影响似乎是幼珊瑚死亡的一个明显因素。这种食草动物在天草的密度比雪子低。因此，两个地区的差异相对减小，小珊瑚的密度在Sesoko Is。4)在生长季节，雪子湖的珊瑚生长速率为。比天草高出1.5倍。如果持续保持5倍的密度，预计Sesoko is的覆盖率将迅速增加。然而，覆盖面如此迅速的变化并没有报道。这一事实表明，一些强大的捕食者，如棘羚和其他有影响的死亡因素导致了密度的减少。然而，这种降低密度的影响因素在天草地区相对少见。根据1990年蝠鲼法对珊瑚分布的普查，天赤洲的珊瑚很少有进食伤痕和部分死亡的现象。5)据报道，天赤洲的大部分珊瑚死亡是在1962/63年冬季的强寒潮期间。表型珊瑚，如Acropora soliataryensis，在天赤草的直径有时可达2米。如果本研究所测得的9毫米直径的年增长率持续30年，那么目前存在的表型珊瑚的最大尺寸与上述报告相符。这说明寒潮过后，天草的硬核珊瑚在良好的条件下生长。孤杉的尺寸频率数据显示出由小到大的连续模式。这种连续的大小结构表明年轻的殖民地是连续定居的。6)在没有强力捕食者的天草，冬低温、夏高温和台风季节的波浪作用是有效的致死因素。许多与珊瑚有关的蛀虫似乎也促成了台风期间珊瑚的减少。少