Effects of habitat structural complexity on diversity patterns of neotropical fish assemblages in the Bita River Basin, Colombia

Abstract

Several studies have shown that fish assemblages are structured by habitat features, most of them have proposed that there is a positive relationship between habitat structural complexity and species diversity. In this study, we aimed to test this positive-relationship idea in three habitats types (creeks, oxbow lakes and river sandbanks) distributed along the Bita River Basin in South America. Standardized surveys were conducted during January and February of 2016 (low water period) in 30 sites distributed along the entire basin. We recorded 23,092 individuals representing 191 species. To investigate possible relationships between habitat structural complexity and species diversity, we calculated the first three Hill’s numbers, and performed a Non-metric Multidimensional Scaling (NMDS), a Principal Component Analysis (PCA) and a Canonical Correspondence Analysis (CCA). Our results showed that river sandbanks and creeks had the highest species richness. Results from the NMDS analysis (stress = 0.19) showed that fish community composition was different in the assessed habitats (ANOSIM < p = 0.001). According to the results of the principal component analysis, sand percentage, dissolved oxygen, and vegetation width separated river sandbanks from the other habitats. Results from the Hill’s numbers, forward selection procedure, and canonical correspondence analysis suggested that species composition and diversity were significantly influenced by the habitat structural complexity index and conductivity.