Abyssal Megafaunal Necrophages: Latitudinal Differences in the Eastern North Atlantic Ocean

Abstract

AbstractA pop‐up time‐lapse camera system (BATHYSNACK) was used to study megafaunal organisms attracted to bait at three abyssal localities in the eastern North Atlantic Ocean, a northern site on the Porcupine Abyssal Plain and two sub‐tropical sites on the Madeira Abyssal Plain. Fish and decapod crustaceans appeared on 47% of photographs taken during deployments of up to seven days duration. The fishes Coryphaenoides (Nematonurus) armatus and Pachycara bulbiceps and the decapod Munidopsis spp. dominated appearances at the northern locality whereas over 95% of records at the two subtropical localities were of the decapod Plesiopenaeus armatus.Cyclical variations in necrophage abundance did not correlate with tidal cycles of near‐bottom currents, although high P. armatus numbers were inversely related to current speed. Most of the frequently recorded entities showed contagious intraspecific distributions. In contrast, many of the interspecies relationships were non‐random, with co‐occurrences lower than expected, probably as a result of physical disturbance or potential predation. Population densities based on times of first arrival were calculated.Assemblages dominated by fish at higher latitudes and crustaceans at lower latitudes are discussed in terms of organic carbon supply to the deep sea and pelagic community structures.