Abstract

GUTIERREZ-C, Angela L  and  PINILLA-A, Gabriel A. Effects of the local connectivity on fish assemblages in a tropical floodplain. Caldasia [online]. 2016, vol.38, n.2, pp.300-313. ISSN 0366-5232.  https://doi.org/10.15446/caldasia.v38n2.60920.

Lagoons of tropical floodplains harbor high levels of biological diversity, play a fundamental role in the life cycles of many organisms and are of great economic importance to local people. This study evaluated the effect of local connectivity on fish assemblages of the San Silvestre (altered connectivity) and El Llanito (unaltered connectivity) lagoons of the Sogamoso River floodplain (Magdalena River basin, Colombia). Samples were collected at three different times during the course of the hydrological cycle and abundance, richness and evenness of fish assemblages were analyzed, along with physicochemical aspects of the lagoons. A total of 37 species were recorded, 28 in El Llanito and 31 in San Silvestre. None of the richness and evenness indices showed statistically significant differences; however clear trends towards higher dominance, lower diversity, and less evenness in San Silvestre compared to El Llanito were observed. There was no significant difference in abundance between the lagoons, but it was greater with lower variation in San Silvestre, while in El Llanito there was a peak in the last round of sampling. Abundance in the two lagoons was concentrated in a few taxa and showed moderate variation over the sampling periods. Temperature, pH, and conductivity values were higher in El Llanito lagoon, while the San Silvestre lagoon had greater depth and flow velocity. This study provides useful information for the conservation of fish resources in the Magdalena River basin, a region of great social and ecological importance that is under considerable pressure from human activities.

Keywords : Sogamoso River; San Silvestre; El Llanito; swamps fish; flood pulse.

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