Plasticity in feeding selectivity and trophic structure of kelp forest associated fi shes from northern Chile
One of the primary ways in which species interact with their environment is through foraging; thereby directly consuming some fraction of their surrounding habitat. The habitat itself, in turn, may dictate the types of foraging opportunities that are available to the inhabitants. To investigate the relationship between habitat availability and diet composition of habitat-associated fi shes, we estimated the relative abundance of the potential sessile and mobile prey items and the diet of the fi sh species assemblage associated to kelp forest. Specifi cally, diet and feeding selectivity of the kelp-forest associated fi sh assemblage were determined by calculating Manly’s alpha selectivity index. We determined the diet of kelp forest associated fi shes and their foraging behavior by comparing prey availability with those items present in the stomachs of fi shes captured by gill net and spear gun. We calculated the degree of dietary overlap among fi shes from four locations along the northern coast of Chile. Results indicate that utilization of prey by predators is predominantly affected by potential prey availability. With the exception of the two carnivorous species such as Pinguipes chilensis (Valenciennes, 1883) and Paralabrax humeralis (Cuvier & Valenciennes, 1828), whose diet did not change among sites, all other kelp-associated fi shes changed their dietary habitats to consistent with the availability of local resources. Benthic resources changed among the different study sites, which led to differing diets even in the same species from different locations. Eleven of the 12 kelp forest fi shes also showed some selectively for benthic prey. We conclude that the ability of fi shes to be plastic in their feeding preference and, therefore, partition the benthic resources may set adaptations to co-exist in a dynamic environment such as kelp forest.