Patterns of development in the epifaunal community at Portsea, Victoria.

This experiment examined the temporal changes in species composition and diversity of a developing epifaunal community on artificial substrata at Portsea. The substrata used were the bare uncaged panels and cage control panels used in the experiment described in the record 'Effects of predation by fishes on the establishment of the epifaunal community at Portsea, Victoria' (File Identifier: fd9aa0f0-e4c2-11dc-9b6b-00188b4c0af8). There were 4 replicate panels that were immersed for 2, 4 or 7 months on rigs under the Portsea Pier and 6 runs of the experiment from October 1975 to November 1977. At the conclusion of each run of the experiment the panels were fixed in 4% formalin-seawater solution. In the laboratory, the number of individuals and percent cover of colonial species on each panel were recorded.In general, the 3 most abundant colonists (barnacle Elminius modestus, tubicolous amphipods and the colonial ascidian Diplosoma rayneri) in the first 2 months decreased as the experiments proceeded. In the following months the surfaces were invariably dominated by arborescent bryozoans, particularly Bugula dentata and Tricellaria porteli and encrusting bryozoans, particularly Celleporaria fusca. Once arborescent bryozoans exceeded a height of 15mm they frequently escaped overgrowth by most encrusting species. In all runs of the experiment there was an initial and usually rapid increase in diversity followed by a decrease.本实验针对波特西港（Portsea）人工基质上发育的表栖动物群落(epifaunal community)的物种组成与多样性随时间的变化展开研究。实验所用基质取自文献记录《维多利亚州波特西港鱼类捕食对表栖群落建立的影响》（文件标识符：fd9aa0f0-e4c2-11dc-9b6b-00188b4c0af8）中的裸露无笼面板与笼式对照组面板。本实验共设置4组重复面板，将其悬挂于波特西码头下方的实验装置，分别浸泡2、4或7个月；整个实验自1975年10月持续至1977年11月，共计开展6轮实验周期。每轮实验结束后，所有面板均采用4%甲醛海水溶液进行固定。实验室分析阶段，研究人员记录了每块面板上的个体数量以及群居物种(colonial species)的盖度百分比。总体而言，实验前两个月内占比最高的三类拓殖生物——藤壶（*Elminius modestus*）、管栖端足类动物以及群居被囊动物（*Diplosoma rayneri*）——的丰度随实验推进逐渐降低。后续月份中，面板表面始终以树状苔藓虫为优势类群，尤以*Bugula dentata*与*Tricellaria porteli*为代表；同时覆层状苔藓虫也占据重要生态位，典型类群为*Celleporaria fusca*。当树状苔藓虫的高度超过15毫米后，它们通常可避免被多数覆层类物种覆生。所有实验周期中，群落多样性均呈现出初期快速上升、随后逐步下降的变化规律。