Population regulation of epibenthic species in coastal ecosystems, with implications for latitudinal patterns

The effect of predation on population regulation among (epi)benthic communities along the Atlantic coasts is reviewed. Population regulation requires density-dependent mortality at some phase in the life cycle, which can occur through predation under certain functional (Type III) and numerical feeding responses. Although the potential to induce regulation has been suggested for some epibenthic predators in the coastal zone, studies linking direct observations of predator–prey responses to observed regulation of the prey population are scarce. The identification of Type III functional response curves is mainly restricted to laboratory or cage studies, and the effect is confined to a limited range of prey densities. Numerical responses, especially predator aggregations, may be more common in the natural environment. The response type seems to be affected not only by habitat structure but also by water temperature. Prevailing temperature conditions can affect the functional response type possibly through changes in predator behavior. The effect of temperature on the response curve appears to be species-specific and hence, predator–prey specific. Therefore, no general effect of latitude on population regulation can be expected. Most likely there is a mosaic of predator–prey interactions that depend on local habitat, temperature conditions, multiple species interactions and predator and prey species types. We surmise that any latitudinal pattern in the overall recruitment variability along species distributional range is more likely to result from a trend in controlling rather than regulating factors.