FEEDING-BEHAVIOR OF BARBUS-BOCAGEI ASSESSED UNDER A SPATIOTEMPORAL APPROACH

The feeding behaviour of Barbus bocagei was assessed in a lowland syst em by a two years survey of two contrasting sites, also taking into ac count, for the first time, diurnal changes of fish diet and benthos av ailability. This barbel feeds more or less continuously during the 24 hours upon the dominant and the most available benthic items, such as Diptera larvae (Chironomidae), Ephemeroptera nymphs (Caenidae), mollus cs and plant material, switching to one or few items when they become common. Such a generalist and opportunistic behaviour was also demonst rated over time by scoring the benthos availability during the second year of this project. In fact, a high spatio-temporal homogeneity of p rey was generally found, whereas significant differences in the gut co ntents occurred by sampling period and site. This lack of correlation may be explained by the existence of intraspecific variation in the fe eding pattern, coupled with the existence of feeding migrations leadin g to exploitation of distinct zones from those prospected.