Vulnerability of Brazilian Sharks to Climate Change: An Integrated Risk Assessment

Abstract

Sharks are important species that occupy different niches and trophic levels due to their biological and behavioural variability. It makes them a key element for conservation measures in marine environments. Among several stressors, climate changes put pressure on species in different ways (direct and indirect) and intensities. Understanding how changes may affect shark species is essential to evaluate measures that reduce the impact on shark populations and help them to adapt to a future climatic scenario. The aim was to identify the levels of vulnerability for Northern and Northeastern Brazil sharks to climate change based on a semiquantitative method of ecological risk assessment. Temperature and UV light were, respectively, the most concerning direct and indirect effects for sharks. In general, most of the assessed species have moderate chances of surviving the pressure caused by climate change. Carcharhinus porosus, Mustelus higmani and Isogomphodon oxyrhyncus were the most vulnerable assessed species. Coastal and estuarine sharks had high rates of exposure and high vulnerability indexes to climate change. Coastal and inshore species generally has high habitat specificity and latitudinal limitation, which worsens its ability to adapt to the new climate scenario. Both parameters may be a crucial factor in preserving coastal shark populations. Continental shelf habitats are commonly affected by other human stressors, such as fishing, waste contamination and destruction of tidal vegetation. In this way, region-specific conservation measures can reduce bycatch and increase reproductive efficiency, increasing the likelihood of coastal sharks surviving climate change. There is still little knowledge about the synergistic effect between human pressure and climate change. However, it is necessary to take measures to preserve the coastal and estuarine environments, so that the biota of these areas show favourable conditions for survival.