The paper investigates tolerance to UV-radiation (UVR) in 3 amphipod species from the Arctic Kongsfjord, Spitsbergen: the herbivore Gammarellus homari (0-5 m water depth), the strictly carnivore scavenger Anonyx nugax (2-5 m water depth) and the detritivore/carnivore species Onisimus edwardsi (2-5 m water depth). In previous radiation exposure experiments, both carnivore species displayed elevated mortality rates already at moderate UVR levels. Therefore the concentrations of sunscreening compounds (mycosporine-like amino acids, MAAs, and carotenoids) and two antioxidant enzymes (superoxide dismutase, catalase) were studied in the animals under control conditions and following moderate as well as high UVR exposure.In both carnivore amphipods elevated sensitivity to experimental UVR exposure went along with a degradation of the tissue carotenoid and MAAs and a decrease of the enzymatic antioxidant defence, which resulted in increased lipid peroxidation in exposed animals. In contrast, the herbivore G. homari seems well protected by high concentrations of MAAs absorbed from its algal diet, and no oxidative stress occurred under experimental UVR. The species-specific degree of UV tolerance correlates well with the animals′ typical vertical distribution in the water column.