THE ROLE OF THE BEHAVIOR ON THE INCIDENCE OF TROPHIC CASCADES

Abstract

Trophic cascades are well accepted mechanisms of top-down regulation in food webs, although its ultimate causes are still in debate. Trophic cascades can emerge through direct effects between populations, where predator consume their prey, decreasing the abundance of preys that affect lower trophic levels. However, trophic cascades can also emerge through indirect behaviorally mediated effects, so that the prey alter its foraging regime in response to predation risk. Such behavioral shifts affect prey foraging effort, reducing its impact on resources. This study presents a synthesis of empirical evidences that support behaviorally mediated indirect interactions as ultimate causes of trophic cascades in a wide range of ecosystems. It was observed that behavioral prey responses in the presence of predators are common in a wide array of ecosystems, strongly affecting patterns at the community and ecosystems levels. It's also noticed that the relative contribution of density or behaviorally mediated effects depends on the biotic or abiotic environmental context. As a conclusion, based on the empiral and theorectical data gathered until now, the use of the behavioral perspective on the food web theory is necessary as an attempt to elucidate the mechanisms that rule trophic cascades and the functioning and structure of ecological communities