Dinâmica Temporal da Estrutura Funcional da Assembleia de Peixes Associada a Bancos de Herbáceas Aquáticas do Lago Catalão, Amazonas

Abstract

Changes in the hydrological periodicity of rivers and their floodplains have significant consequences for biodiversity and overall system productivity, affecting ecosystem processes (ex. Food web control) and services. In this context, the present study aimed to verify the temporal dynamics in the functional role of the assemblage of fish that colonize aquatic herbaceous in the face of variations in hydrological cycles that occurred over a period of 14 years (from 2004 to 2017). The study was developed in the Catalão System located at the meeting between the Negro and Solimões rivers. The fish samples came from collections already carried out in the aquatic herbaceous banks of the long-term Project “Ecology and Conservation of Freshwater Fish”. We considered the collections made during the peak period of the flood of each year analyzed. The functional structure of the assembly was determined through ecomorphological analysis of 96 species. These measures were combined into 12 functional attributes and quantified by applying the functional index CWM (Functional Community level Weighted Means). This index indicates the functional identity of an assembly, and corresponds to the average value of the characteristics of all species present in the community, weighted by their relative abundances. The Euclidean distance was used to generate the functional distance matrix between each pair of species. Subsequently, we performed Principal Coordinate Analysis (PCA) on the functional distance matrix to build a multidimensional functional space. A total of 96 species that appeared during the flood period in the years studied were analyzed. Regression analysis did not indicate significant general changes in the assembly over time. The CWM values remained stable, but with an emphasis on the years 2014 and 2015. Stability in the ecological functions of the assembly is likely to reflect the high diversity of species. Redundant functions can be performed by different species, thus attenuating the effects of disturbances resulting from changes in hydrological cycles.