Diversity and structure of fish assemblages in the wetland, caños and esteros of the Ariporo River floodplain, Casanare, Colombia

Abstract

Flooded savannas are an important biome for the functionality and diversity of the Orinoco fish communities. These savannas have high connectivity and ecosystemic diversity including the configuration of different types of wetlands. Understanding how fish communities are structured is critical for biological conservation. Here we aimed at determining the diversity, composition, and structure of fish assemblages in the caños of the river-floodplain complex and in the esteros in the peripheral system of the Ariporo River flooded savanna in Casanare (Colombia). We sampled seven sites (four in caños and three in esteros) during two hydrometric seasons in descending and low waters. In each site, we collected fish with a 10 x 1.5 m seine net (2 mm mesh). We analyzed the structure and diversity of fish communities using distribution-abundance models, Hill numbers, non-metric multidimensional scaling analysis (NMDS), and the indicator species index (IndVal). Our results evidenced that caños had the highest richness and species diversity. The NMDS analysis (stress=0.00009) showed two fish assemblages depending on the wetland type. In caño fish assemblages we registered specialist indicator species, but not in the esteros. These results suggest that caños have more complex and diverse fish assemblages while esteros assemblages are dominated by generalist species.