Abundancia relativa y dieta de Grundulus bogotensis (Characiformes: Characidae) en el altiplano Cundiboyacense, Colombia

Abstract

To compare the relative abundance of Grundulus bogotensis in two river basins and the diet of the populations of three basins in the Cundiboyacense plateau, we sampled 10 localities using electrofishing equipment between March and June 2006. The relative abundance in each locality was expressed as the number of fish caught per hour on a 100m stretch; any significant differences in relative abundance among basins were identified via a Kruskal-Wallis test. To quantify the diet, we used the volumetric method. Similarities between the basins were determined using three multivariate analyzes: nonmetric multidimensional scaling, analysis of similarity and similarity percentages. In the end, we collected a total of 675 individuals during 600 minutes of capture effort. The abundance of this species in the Bogotá river basin was significantly lower compared to that of the Suárez basin. The dietary composition, of autochthonous origin, primarily immature insects and microcrustaceans and the volume of items proved similar between the basins. In conclusion, the dietary analysis indicated a similarity exceeding 60% in the feed resource use for the three basins. The relative abundance of populations of G. bogotensis in the Bogotá river basin was lower than in the Suárez river basin, the latter having, possibly, the greatest abundance of this species throughout its range. The data suggests the most favorable conditions for the survival of the species in Lake Tota.