Efeito das mudanças climáticas sobre a distribuição de cianobactérias no semiárido brasileiro

Abstract

Climate change causes universal challenges and intergenerational impacts. Global climate warming has been observed since the Industrial Revolution and has led to a shortage of natural resources, causing different effects such as changes in precipitation and temperature patterns. These variables are essential for the occurrence of aquatic species, as they affect resource availability and can alter the biogeochemical processes that regulate the life cycle. Empirical evidence indicates a sharp increase in the proliferation of cyanobacteria with climate-related changes. Cyanobacteria are photosynthetic organisms that occur in marine and freshwater environments, grouping around in colonies or filaments, and many species can produce potentially toxic blooms. In the semiarid region of Brazil, the occurrence of cyanobacteria is widely recorded in reservoirs for multiple uses, including public supply, and may affect biodiversity and human health. In this study we tried to understand the current and future distribution of environmental cyanobacteria (colonial and filamentous) that produce toxins in the Brazilian semiarid region using the niche modelling approach to estimate the areas suitable for the establishment of these populations, associating the already known occurrence points with the bioclimatic variables inherent to the ecology of the species and the climate scenarios (moderate and pessimistic) projected by the Intergovernmental Panel on Climate Change (IPCC) focusing on the time interval 2081-2100. Isothermality, annual temperature variation, precipitation volume of the wettest, coldest and driest quarters, plus the elevation were the variables most important for the potential distribution of the species. The projections showed that the Brazilian semiarid region has high climatic suitability for the occurrence of all scientific species, but the models indicated the expansion of habitat suitability in the future, both in the moderate and pessimistic scenarios, only for Microcystis aeruginosa (colonial) and Planktothrix agardhii (filamentous). Therefore, the results obtained suggest a link between temperature and precipitation variability effects on the distribution patterns and adaptive strategies of the species.