Community organization of associates of the scleractinian coral Pocillopora damicornis

本文研究了大角短尾轮虫专性共生体--黄蟹(Trapezia app.)、斑节对虾(Alpheus Lottini)和虎鱼(Paragobiodon app.)专性共生体对珊瑚群落结构的影响，以及它们的群体大小和种内相互作用。物种丰富度和多样性(H‘)及伴生动物数随群体大小增加而增加，而均匀度(J’)不变且较高。在分枝间隙体积小于1.5 cm~3的菌落中，未发现专性共生体。专性共生体的种类和数量随着种群规模的增大而增加：1.5-12cm3--1个斜长藻或Cymo；15-23cm3-2种，每种1个；24-71cm3-2种，其中包括1个异性对；74-264 cm3-2或3种，包括2 6R3个异性对；331cm3--形成复杂群落的4种以上物种(在1,980 cm3的种群中，最多10种)。雌性斜纹夜蛾能驱逐所有引进的较小的斜纹夜蛾个体，但经常被较大的引进蟹排出。Alpheus lottini有时会驱逐引进的Trapezia，但Trapezia很少对A.lottini表现出攻击性行为。洛蒂尼天牛对同性别的同种入侵者的攻击性最强，导致每个群体出现一对异性对。栖息地的承载能力与种群大小有关，居民和入侵者之间的物种相互作用是相关动物群落组织过程中的重要因素。

Colony size and the inter and intraspecific interactions of the obligate symbionts of Pocillopora damicornis, i. e. xanthid crabs(Trapezia app.), a snapping shrimp(Alpheus lottini)and gobies(Paragobiodon app.), are examined in terms of their effects on the community structure of the coral associates. Species richness and diversity(H')and the number of associated animals increased with colony size, while eveness(J')was constant and high. In colonies with less than 1.5 cm3 interbranch space volume, no obligate symbionts were found. Obligate symbiont species and numbers increased with colony size : 1.5-12 cm3 --one individual of Trapezia or Cymo ; 15-23 cm3 --2 species, one individual each ; 24-71 cm3 --2 species including one heterosexual pair pf Trapezia or Paragobiodon ; 74-264 cm3 -- 2 or 3 species including 2 6r 3 heterosexual pairs ; . 331 cm3 --more than 4 species forming complex communities(maximum of 10 species in a colony of 1, 980 cm3). Females of Trapezia cymodoce expelled all introduced smaller individuals of Trapezia spp., but were frequently expelled by larger introduced crabs. Alpheus lottini sometimes expelled introduced Trapezia, but Trapezia rarely showed aggressive behavior toward A. lottini. A. lottini is most aggressive against conspecific intruder of the same sex, resulting in the occurrence of one heterosexual pair per colony. Carrying capacity of the habitat which is related to colony size, and species interactions between the residents and intruders are important factors in the organizing process of the associated animals community.