Colonization of ephemeral resource patches by vagile consumers: the importance of body size

The potential of ephemeral resource patches (ERPs) to contribute to central ecological issues has been recently acknowledged, in particular for the diversity-function debate. Due to their intrinsic spatial-temporal heterogeneity and dissipative ontogeny influenced by consumers from different trophic levels, ERPs can be used for further testing hypotheses on mechanisms driving the assembly of animal communities. Here, the results of a study on the colonization of decaying leaf detritus patches by vagile macrobenthic invertebrates are presented in the framework of a conceptual model where body size-related constraints on patch use behaviour are explicitly considered. Invertebrate abundance patterns were characterised by short-term, nonrandom fluctuations, showing significant site-dependent variations. Yet, a site-independent covariation was observed between the fractal dimension of abundance patterns and the average body mass of each taxon, indicating that, while the temporal scales characterising ERPs colonization patterns may be highly speciesspecific, cross-species generalizations are possible based on body size. The generality of these results was supported by literature data on i) temporal patterns of carcass colonization by bathyal fish and ii) spatial patterns of detrital patches colonization by terrestrial invertebrates. The importance of size-related mechanisms in regulating the aggregation on ERPs of vagile consumers and, ultimately, their coexistence at both an inter- and intra-specific level, is discussed.