Estrutura e distribuição espacial de assembleias de peixes sob influência de ressurgência costeira

Abstract

In the current climate change scenario understanding how fish assemblages respond to meteo-oceanographic processes is essential for assessing future impacts on reef environments and their biodiversity. In upwelling zones, the high variability in water temperature and primary productivity can alters composition and distribution patterns of benthic and pelagic marine communities. However, its effects on brazilian subtropical reef fish distribution are still poorly understood. For this purpose, 69 baited remote underwater stereo-video (stereo-BRUVS) samples were distributed between regions of high (external) and low (internal) influence of upwelling waters inside the Arraial do Cabo Marine Extractive Reserve. The upwelling-induced environmental variability added to the physical characteristics of the environment (habitat type and depth) give rise to two distinct fish assemblages in composition, structure and functioning. The internal region has an assemblage composed mostly by species of tropical origin, more abundant, richer and with biomass distributed more homogeneously among trophic groups. In contrast, the external region presents an assemblage dominated by species of subtropical origin in lower abundance, richness and with biomass concentrated in groups of higher trophic levels. It has also been observed that internal reefs act as developmental areas for some of the most abundant species, probably in response to the greater refuge availability and lower abundance of predators and adult fish. In the short term, this information is useful to elaboration of strategies for conservation of local ecosystem resources and services, such as areas where human activities are prohibited and scientific research encouraged. In the long term, they can serve as comparative baselines for future climate change scenarios, where the intensity of meteooceanographic processes and divergences between regions tend to be more pronounced.