Pattern in the Development of a Marine Community1

The development of a community on experimental 1‐m cubes of asbestos board on iron frames placed at 12–14‐m depth off La Jolla has been examined in terms of the processes leading to patterns of distribution. Differences between the cubes in vectorial factors were kept to a minimum. However, vectorial processes affecting them all, especially water movement, were important in forming and maintaining the community. Only one pattern was clearly ascribable to reproductive processes: spread of a budding anemone. Patterns due to social action were seen in the schools of fish that fed around the cubes. There was competition for space between the anemone and a bushy bryozoan. Competition was not evident within several congeneric pairs that were prominent components of the community. Chance processes appeared to be the causes of differences between the cubes in species composition and size of the large brown algae and in the occurrence and abundance of small fish and nudibranchs. The algae were major contributors to the physical structure of the community; the fish and nudibranchs were important in the food web. The similarities of this community with other more complex ones were considerable: the key role of “detritus,” the constant flux of individuals and species, the stability of numbers of many species, and the qualitative and quantitative variations on a basic species list.