[Capture and selectivity of zooplankton by Utricularia foliosa (Lentibulariaceae) in the Ciénaga de Paredes, Santander, Colombia].

Utricularia is a genus of carnivorous plants that capture a wide range of aquatic organisms. Most of these plants grow in environments with nutrients deficiency and have the ability to change the conditions of their microenvironment. The aim of this research was to study the selectivity in the zooplankton capture by Utricularia foliosa in the Ciénaga de Paredes. Our study was undertaken between February and November, 2014. We tried to determine if there is selection in the plant’s food resources by the Czekanowski’s index, and the selection degree by the Savage and Ivlev’s indexes. Additionally, we studied the possible relationship between the patterns of zooplankton capture and selection, with physicochemical variables in the swamp. The Czekanowski’s index showed a food selection in plant resources throughout the flood pulse, with values between 0.28 and 0.41. We also found a significant positive selection with Savage's index for Lecane sp., Alona sp., Ceriodaphnia sp., and Bosmina sp. (p < 0.05); similar results were obtained with Ivlev’s index. The intensity in the selection of each captured genus varied significantly between hydrological periods and between high and low water levels in the swamp. It was possible to identify some changes in the ammonia and nitrate concentration and some variability in the electric conductivity of the swamp, which influenced the captures made by U. foliosa. This is the first paper that allows an approach to understand the selection of food resources for the species, using a selectivity index, and one of the few for the genus.