Aggregations of Arctic deep-sea scavengers at large food falls: Temporal distribution, consumption rates and population structure

Abstract

Scavenging amphipods were studied at 6 locations in the Fram Strait (Arctic Ocean). At each location a tripod lander equipped with a time-lapse camera, acoustic doppler current profiler and baited traps was deployed at water depths between 1500 and 2600 m. All amphipods, both on photographs and captured, belonged to the superfamily Lysianassoidea or Stegocephaloidea. Differences between the stations occurred in time and number of amphipod maxima, consumption rates, taxonomic composition, size structure and current direction. Scavenger aggregation dynamics and behaviour on carcasses in the Arctic Ocean differ from those in other reported deep-sea areas in arrival time at bait, abundance and length distribution of individuals sampled. The giant amphipod Eurythenes gryllus dominated in our bait experiments; it exceeded numbers counted by other workers by >13-fold, and the first individuals appeared up to 20 times faster than in other reported experiments. Specimen attraction and abundance seem to be directly linked to the organic input of food falls in the area. Relations between scavenger aggregations and trophic conditions are discussed with respect to results obtained under different trophic regimes in the Arabian Sea and in the Pacific and Atlantic Oceans. © Inter-Research 2006.