Does fish size affect trophic cascades?

Understanding the ecological consequences of human activities has become a central issue in ecology. A large number of studies have shown that anthropogenic biodiversity loss is not random, but is biased against large vertebrate consumers at the top of trophic networks, and results in trophic cascades in all of the world major biomes. Moreover, recent studies have demonstrated that anthropogenic perturbations also induce rapid change in morphological traits (in particular rapid body- downsizing) which may be pivotal to ecological functioning, in fact this rapid change could also impact trophic cascades.

However, studies interested in the effects of biodiversity loss are mostly focused on the presence - dependent effects of predators without taking into account the morphology-dependent effects. In our experimental study, we have specifically quantified the respective contributions of predator presence (0 or 1 density) and morphological traits (body size and shape) to the strength of a fish-induced trophic cascade.

Our results show that the strength of size-dependent effects of fish may dominate the strength of their presence-dependent effects in the trophic cascade. Therefore, our study suggests that accounting for rapid anthropogenic body-downsizing is necessary to predict and manage the consequences of biodiversity loss, and further advocates for a better integration of trait-dependent interactions into classical ecological theory.

Clementine Renneville

Comments