Ecological studies on the coral reef communities in the Gulf of Thailand (The second expedition)

在泰国湾的西昌群岛，对珊瑚带附近沙质底质上的非珊瑚礁珊瑚群落和底栖生物群落进行了深入的实地研究。我们的最终目标是解释为什么即使在热带海域也没有在浑浊的水域建造珊瑚礁。对以Porites为主的珊瑚群落中组成珊瑚的空间排列和大小组成进行了深入的测绘研究，并详细分析了竞争物种之间的相互作用。结果表明，在非礁珊瑚群落结构过程中，捕食性和厌食性动物在群落结构过程中起着重要作用。我们的发现表明，解释为什么在海湾环境中悬浮物丰富的浑浊水域中能够保持Diadema和其他食草动物以及各种讨厌的生物的超级丰富是重要和不可或缺的。在沙质海底，通过野外调查和野外实验，研究了海胆的分布和丰度，分析了海胆在造成环境异质性中的生态作用。令人震惊的是，Spatangoid海胆的持续觅食活动通过制作漏斗(用粗沙和砾石)和土丘(用细沙)来造成底部不规则。这种海胆的作用对于构建支持不同底栖生物群落的底栖微生境非常重要。沙质海底的另一个显著之处是大量自由生活的珊瑚。利用自然自体切割法对其分布、种群结构和无性繁殖进行了研究。

In the Sichang Islands, the Gulf of Thailand, intensive field studies were conducted for the non-reefal coral communities and the benthic communities on the sandy substrates adjacent to the coral zone. Our final target is to explain why the coral reefs have not been constructed in the turbid waters even in the tropical seas. Intensive mapping studies of the spatial arrangements and size compositions of the constituent corals in the Porites-dominated coral communities and detailed analysis of the competitive species interactions were conducted. The results, otgether with the observations of the great abundance of Diadema and boring animals, suggested the important roles of the grazing as well as boring animals in the non-reefal coral community structuring process. Our findings suggest that it is important and indispensable to explain why the super abundance of Diadema and other grazers and a variety of boring organisms can be maintained in the suspension-rich turbid waters in the bay environment. On the sandy bottom, we studied the distribution and abundance, and analyzed the ecological role of the sea urchins in the creation of environmental heterogeneity by field survey and field experiments. it was very striking that the continuous feeding activity of a spatangoid urchin, Brissus latecarinatus, creates bottom irregularities by making a funnel (with coarse sands and gravels) and a mound (with fine sands). The role of this urchin is very important for structuring the benthic microhabitats which were proved to support different benthic communities. The other remarkable point of the sandy bottom is the great abundance of free-living corals. Of these, Diaseris fragilis was studied for its distribution, population structure, and asexual reproduction by means of natural autotomy.