Species richness and the proportion of predatory animal species in temporary freshwater pools: relationships with habitat size and permanence

The proportion of predatory animal species is often believed not to vary sy stematically across communities. However, we predict that larger temporary freshwater pools, and pools that are more permanent, will contain a higher proportion of predatory animal species. In 24 temporary rockpools in Northe rn Israel (supporting communities dominated by ostracods, copepods, cladoce rans, flatworms, dipterans and amphibians), the mean proportion of macrosco pic predatory species (averaged over a series of samples) increased with in creasing pool area. For the highest possible proportion of predatory specie s (including microscopic species with uncertain diets), the relationship wi th pool area was not statistically significant We did not find significant relationships between permanence and the proportion of either macroscopic o r all possible predatory species. Larger pools and pools that were more per manent had more species. Species richness and the proportion of macroscopic predators mere positively correlated. These patterns imply that species-po or ecosystems are likely to be functionally different from species-rich sys tems.