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

在泰国湾泗昌群岛，对珊瑚带附近砂质基质上的非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的浑浊水域也没有建造珊瑚礁。研究人员深入研究了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，并详细分析了竞争物种的相互作用。结果表明，放牧和放牧动物在非礁珊瑚群落构建过程中发挥了重要作用。我们的研究结果表明，解释为什么在海湾环境中富含悬浮液的浑浊水中可以维持Diadema和其他食草动物和各种无聊生物的超丰度是重要和必不可少的。通过野外调查和野外实验，研究了沙质海底海胆的分布和丰度，并分析了海胆在环境异质性形成中的生态作用。非常惊人的是，一种名为Brissus latecarinatus的spatangoid海胆的持续进食活动，通过形成漏斗（含粗砂和砾石）和丘（含细砂），使底部不规则。海胆在构建底栖生物微生境中起着重要的作用，这些微生境已被证明可以支持不同的底栖生物群落。沙质海底另一个引人注目的地方是大量自由生活的珊瑚。利用自然自切法研究了脆弱一水堇的分布、种群结构和无性繁殖。

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.