Gut evacuation in barbel (Barbus sclateri G., 1868) and nase (Chondrostoma willkommi S., 1866)

Abstract

Abstract– In this study we estimated the rates of summer gut evacuation for two cyprinids with detritivorous‐omnivorous feeding habits, Barbus sclateri, Günther 1868 (barbel) and Chondrostoma willkommi, Steindachner 1866 (nase). This study was performed at two sampling stations in the upper Guadalete River (south Spain). A previous study reported differences in the natural diet of both species. The gut evacuation rate was estimated from the regression of gut contents weight against time. Linear and exponential models best described the pattern of gut emptying in the two species. There was no significant difference in the gut evacuation rate between both sampling stations for barbel. However there was a discrepancy related to the model that provided the best fit to empirical data. In contrast, the same model provided the best fit to the empirical data for nase in both sampling stations, but the gut evacuation rate was significantly different in both sampling stations. The results of these study provide the first data of evacuation rates for Iberian freshwater fish species directly measured in the field.