Risco de dispersão de espécies exóticas: similaridade ambiental e mudanças climáticas

Abstract

Climate change and biological invasions represent the most threats to marine biodiver- sity and ecosystem stability. Despite ongoing efforts to reduce the transfer of organisms, the annual rate of new introductions continues to rise, with no signs of saturation in the accumulation of exotic species on a global scale. By the end of the 21st century, it is ex- pected that ocean temperatures may reach critical levels, increasing by up to 3◦C above the global average. This study aims to assess the effect of climate change on the envi- ronmental similarity between the world’s marine ecoregions (MEOW), and to develop a method to identify areas vulnerable to the dispersal of two exotic species to the coast of Brazil: the oyster Saccostrea cuccullata and the vermetid Eualetes tulipa. The environ- mental similarity between the MEOW and the probability of dispersal of S. cuccullata and E. tulipa was evaluated considering a reference period (PR) - (2000-2014) and two climate change scenarios (MC) - RCP2.6 (peak and decline scenario) and RCP8.5 (high warming). A generalized linear model was employed to assess the environmental simi- larity among the MEOW using a dataset of temperature and salinity. A model/classifier based on Random Forest (RF) was trained and validated using georeferenced records of the target species to identify regions vulnerable to potential dispersal events of these species. If climate change scenarios come true, the poles (Arctic and Antarctic), as well as the temperate zones of the Atlantic and Pacific (Northern Hemisphere) would be the regions most susceptible to the impacts of global warming. Hence, the establishment of tropical and subtropical marine species at higher latitudes would be favored. Changes in temperature and salinity patterns resulting from climate change can redefine the geographical distribution limits of species. This is because alterations in environmental characteristics can modify the compatibility between species and their surroundings. Using the exotic species S. cuccullata and E. tulipa as models, the RF-based method developed enabled the identification of areas vulnerable to the introduction/dispersal of exotic species within the maritime zone of Brazil under scenarios. The algorithms showed that 33% of the Brazilian maritime zone is susceptible to the dispersal of S. cuccullata, with a potential reduction in the area due to changes in temperature and salinity. Meanwhile, 4% are susceptible to the dispersal of E. tulipa, with the possibility of an increase. Although the processes of dispersal and extinction of species naturally modulate biogeography, the results indicate possible changes in the distribution patterns of marine organisms as a result of changes in environmental similarity on a global scale. Identifying vulnerable areas for the introduction and dispersal of exotic species under different climatic scenarios can inform the development of strategies for conserving natural resources, including biodiversity hotspots.