Papel do impacto do clima na distribuição de Cianobactérias em ambientes aquáticos neotropicais de água doce

Abstract

Neotropical freshwater environments are among the most productive ecosystems and provide many ecological products and services to humanity. In neotropical freshwater aquatic environments, climate change is a threat to global water security, and extreme hydrological periods such as extreme precipitation or extreme drought will undoubtedly restructure food chains, generating new communities composed of new combinations of species. In freshwater bodies, extreme events in climate change can intensify the bloom of toxic cyanobacteria (CyanoHABs). In general, the geographic distributions of cyanobacteria are poorly known and present numerous information gaps (Wallacean deficit) often related to the lack of collection efforts. In this thesis the available data on the geographic distribution of cyanobacterial species in freshwater environments are far from complete and have obvious geographic biases. Many of the records of cyanobacteria in aquatic environments were not accessible, which may have reduced the ability to assess species distribution. The results presented here can provide relevant information about sampling gaps in regions that need further research to improve distribution data on the occurrence of these species and support monitoring practices for these species. In general, our maps present available data on the areas with suitability for toxic cyanobacteria and our sampling effort was invested in South America. In chapter 1, we present a scientific dissemination article, containing information and scientific concepts about cyanobacteria and their blossoms. In chapter 2, we describe the number of publications collected in the scientific literature that documented the occurrence of cyanobacterial blooms over the years, as well as the responsible orders and the records of the Brazilian states where they occurred. In addition, we used the occurrence data obtained in this scientometric investigation to estimate climatically suitable areas for the occurrence of cyanobacterial flowering events. In chapter 3, we use ecological niche modeling tools from occurrence records collected from available databases to predict the susceptible areas in South America for the present and future scenario of the Phylum Cyanobacteria represented by: Microcystis aeruginosa (Kützing) Kützing 1846, Planktothrix agardhii (Gomont) Anagnostidis & Komárek 1988 and Raphidiopsis raciborskii (Woloszynska) Aguilera, Berrendero Gómez, Kastovsky, Echenique and Salerno 2018. We consider three different modeling methods: Generalized Linear Model (GLM); Gaussian Model (GAU) and Maximum Entropy (MXS). In the results, the distributions for the current scenario were consistent with the known distributions and, for the future scenario, we identified new areas of research. We conclude that the modeled species respond to current and future environmental changes and that the Phylum must occur in areas that are currently not detected in our ENM analysis.