The food composition of the shrimp Crangon allmanni from the Helgoland Trench (North Sea) and Onega Bay (White Sea) is described. The main food items (>60%) include detritus, representatives of about 30 benthic species, dominated by polychaetes, malacostracans, ophiuroids, bivalves and ophistobranchs (Cylichna, Diaphana spp.) as well as plant remains. In the North Sea, C. allmanni is closer to an attacking predator than to a predator-gatherer like in the White Sea. This difference may be caused by diverging habitat- and community characteristics and dissimilar size composition of the two studied shrimp populations. Moreover, C. allmanni changes its foraging mode (grazing, gathering, attacking) during ontogenesis. A comparison of the obtained food composition data of C. allmanni with literature data on six other species of the same genus showed all to be benthos feeders, predator-gatherers with elements of detrito- and necrophagia, using grains of sand as millstones in their gastric mill.
Modelling the effects of fishing on the North Sea fish community size composition