Body-size distribution in a marine metazoan community and the fractal dimensions of macroalgae

Abstract

Habitat architecture has two major components, size and structural variety. Both these attributes are incorporated in measurements of fractal dimensions which are essentially an expression of habitat size in relation to the scale of measurement. Therefore, the fractal dimensions of a habitat, coupled with energy requirements, may be one explanation for the species abundance/body size distribution of the associated animal assemblages. This concept is tested in the marine environment by an analysis of the fractal dimensions and epifaunal assemblages of four species of macroalgae on the Isles of Scilly. It is shown that the slope of the regression of animal abundance against body size (estimated by sieve mesh size) is related to the fractal dimension of each weed. The application of the energetic equivalence rule, however, overestimates the abundance of smaller animals. In general, smaller animals appear to use proportionately less of the community resources. It is suggested that this is a result of unequal availability of resources due to the different feeding and resource partitioning traits between macrofauna and meiofauna.