PASSING THE GUT OF JUVENILE FLOUNDER, PLATICHTHYS-FLESUS - DIFFERENTIAL SURVIVAL OF ZOOBENTHIC PREY SPECIES

We studied the resistance of benthic prey organisms (Ostracoda, Hydrob ia spp., Macoma balthica) to digestion by juvenile flounder, Platichth ys flesus (L.), in a series of aquarium experiments. Results showed th at some food species are able to survive the gut passage (Ostracoda 53 to 75%, Hydrobia spp. 46 to 92%). This has ecological implications, a s increasing eutrophication of the Baltic Sea favours prey species tha t are nondigestible for the juvenile flounder. Thus, seemingly small c hanges in food-web structure may have unpredictable effects for the pr edatory fish.