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

在泰国湾的四昌群岛，对非礁珊瑚群落和邻近珊瑚区的桑迪底质上的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珊瑚礁没有在浑浊的沃茨中建造，即使在热带海域。对Porites占主导地位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绘图研究，并详细分析了竞争物种的相互作用。结合大量的迪亚德马和钻蛀动物的观察结果，说明了食草动物和钻蛀动物在非礁珊瑚群落结构形成过程中的重要作用。我们的研究结果表明，这是重要的和必不可少的，以解释为什么超级丰富的迪亚德马和其他食草动物和各种钻孔生物可以维持在悬浮物丰富的混浊沃茨的海湾环境。在桑迪底质上，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。令人惊讶的是，一只匙形海胆（spatangoid urchin）--这种海胆的作用是非常重要的结构底栖微生境，证明支持不同的底栖群落。桑迪海底的另一个显著特点是大量的自由生活的珊瑚。本文对其中的脆弱盾蚧的分布、种群结构和自然自断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.