Effect of human impact on coral reef herbivorous fish niche

Abstract

The lower abundance, biomass, and homogenization of sizes of herbivorous fish caused by overfishing may lead to a disproportionate loss of functions. The present work explores to which extent fishing affects species niche and functions by comparing the isotopic niche breadth and redundancy and resource use in a herbivorous fish community. While the video analysis was not able to discriminate large differences in feeding preferences, all ate preferentially the epilithic algal matrix (EAM), the SIA suggests that within the marine protected area (MPA) fish may be feeding on more diverse sources (greater amplitude of isotopic niche) and have more overlapping niches (greater redundancy). Corroborating with works that claim that the delimitation of MPAs can contribute to the redundancy of functions and resilience of coral reefs. For clarifying if fish are using (preying on or digesting) different resource species or same, the species in different environments with different basal SI values would definitively need to have a better isotopic characterization of resources within the MPA. Our work contributes to new discoveries that have implications for the conservation of coral reefs, as fishing appears not only to affect the biomass and body size of herbivorous fish but also reduces the trophic niche of fish species, compromising many of their ecological functions.