Influência de fatores locais e regionais na diversidade funcional da ictiofauna de riachos da bacia do Rio de Contas

Abstract

The study of the functional diversity of biological communities allows us to understand how species overlap or complement each other concerning their role in the functioning of the ecosystem to which they belong. Regarding fish assemblages, functional diversity is influenced by local factors such as the physicochemical structure of the environment, as well as regional factors like climatic characteristics and land use. Therefore, understanding the relationship between abiotic factors and the functional characteristics of species is essential for understanding the response of communities to environmental changes, aiding in the management and conservation of aquatic ecosystems. In this perspective, we analyzed the functional diversity of fish assemblages in streams within the Chapada Diamantina and Atlantic Forest regions, in the Contas River basin, based on local and regional variables. We established 18 sampling points for ichthyofauna and for local and regional environmental characterization. The functional diversity of the ichthyofauna in each stream was assessed using the following indices: Functional Richness, Functional Evenness, Functional Divergence, Functional Specialization, and Functional Redundancy. The relationships between the indices and local and regional variables were examined using Generalized Linear Models. We found that the indices of functional diversity did not show significant differences between the two regions studied, but there were significant variations among the streams within each region. The effect of local and regional variables differed among the considered indices, where local variables were more influential for Functional Richness and Functional Evenness compared to regional ones. For Functional Divergence and Functional Specialization, regional variables were more representative than local ones, while Functional Redundancy showed no relationship with the sets of variables included in our study. Thus, our study emphasizes the importance of understanding the functional diversity of fish assemblages in streams, considering both local and regional factors, and underscores the continuous need for studies in this area to mitigate the increasing loss of biodiversity and to create conservation strategies for aquatic ecosystems.