DISTRIBUIÇÃO ESPAÇO-TEMPORAL DAS ASSEMBLEIAS DE PEIXES UTILIZANDO DESCRITORES FUNCIONAIS (GUILDAS TRÓFICAS E CLASSE DE COMPRIMENTO) NO RIO VERÍSSIMO, BACIA DO PARANÁ, GOIÁS, BRASIL CENTRAL.

Abstract

The main objective of this study was to test if fish assemblages along Veríssimo river varied spatially and temporally in relation to the functional descriptors trophic guild and length class. In four stretches of the river, we sampled species quarterly between April/2008 and June/2009 using five traps (minnow-traps) and four sessions with gillnet. We selected sixteen species for the analyses which were present in all sampled points. We constructed a functional matrix for each descriptor considering relative abundance data (%). For each matrix we performed a nonparametric analysis (Kruskal-Wallis) followed by a post hoc analysis (multiple analyses) to verify if there are differences between the four sampling points of the river. We realized a Spearman correlation analysis between each matrix and the river width and, then, a Principal Component Analyses (PCA) to verify if sampling points could be ordered by the functional descriptors. All analyses above were performed using the software Statistica 7. We tested temporal synchrony of the functional descriptors using each functional matrix for a multiple co-inertia analysis (ACOM). These analyses were performed in software ADE-4. Differences between four points sampled were higher than expected by chance for trophic guild and length classes (p<0,0001 for both descriptors). Our post hoc analysis indicated differences higher than expected by chance between points P3 and P4 for trophic guild (p <0,01) and length classes (p<0,001), however, these differences are not correlated with river width. PCA analyses demonstrated that species from length class A (71,22%) and omnivores (30%) were more associated with point P4 while iliophagous fishes (56,17%) and those belonging to length class B (53,64%) are more associated with point P2. ACOM results demonstrated that points P2 (COS2 = 6,425 e 01; COV2 = 4,654 e + 00; RV = 0,82) and P3 (COS2 = 8,156 e - 01; COV2 = 3,186 e + 00; RV = 0,87) have a variation in their temporal pattern similar for what is expected for trophic guild and have a better synchrony. In the case of length classes, points P3 (RV = 0,82) and P4 (RV = 0,81) presents a better synchrony. Starting from the fifth sampling (January), we observed changes in the synchrony of functional descriptors. Spatial and temporal patterns of distribution from fish assemblages in Veríssimo river seems to reflect seasonality and the migratory behavior of the species Steindachnerina insculpta.