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.