Browsing by Author "Mallmann, Antonia Ivone Marieke"
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- Mid-trophic generalists dominate reef fish community impacted by overfishingPublication . Mallmann, Antonia Ivone Marieke; Serrão, Ester; Freitas, RuiOverfishing is one of the most severe threats to oceans globally and predates all other human impacts on the marine environment. A common tool to manage fisheries sustainably are marine protected areas (MPAs). However, to achieve the desired results effective management plans integrating continuous monitoring need to be in place. This study assessed the MPA effect of nine sites within the Santa Luzia marine reserve, by employing diver-operated stereo- video transects along with an assessment of the benthic composition to account for natural variability. Specifically, differences to a previous assessment in 2009 were evaluated in terms of reef fish relative biomass by trophic group, relative densities and frequency of species using multivariate analyses and change of community descriptors (species richness, diversity, and evenness). In 2022, the community was dominated in terms of biomass and density by two pomacentrids of the genus Chromis and three omnivorous sparid species of the genus Diplodus. A pronounced shift from a more specialized community in 2009 with high proportions of the biomass at the lower and upper end of the trophic spectrum, to a more homogenous community dominated by mid-trophic generalists was observed. There was no significant difference between the benthic cover composition and fishing intensity is the only environmental predictor that was weakly related to community composition. In the virtual absence of natural variation accompanied with over 20% loss of species richness and significantly higher evenness, the reef fish community of Santa Luzia exhibits signs that previously have been related to high fishing pressure. The functional redundancy of reef fishes was heavily impacted, and the implementation of more effective management measures is necessary to restore the reef fish community and ensure ecosystem functioning.