Feeding Ecology and Carbon Transport of Diel Vertically Migrating Myctophids from the Northern Mid-Atlantic Ridge

Myctophids are among the most abundant vertically migrating fishes in the world’s ocean, however little is known regarding their contribution to carbon export. We quantified diel depth distribution and analyzed the diet of myctophids from the northern Mid-Atlantic Ridge (MAR) between Iceland and the Azores in order to elucidate their role in the MAR food web and carbon export. The myctophid Benthosema glaciale was the numerically dominant fish from the MAR, constituting 35% by number of the total fishes caught. This species was largely zooplanktivorous, with copepods and euphausiids comprising 59% and 15% of the diet by weight, respectively. By consuming zooplankton in surface waters and metabolizing their food at depth, myctophids may contribute to the biological pump, although, carbon actively transported to depth by migrating myctophids at the MAR varied along the ridge and was lower than export by vertically migrating zooplankton in the North Atlantic estimated in other studies. Due to their high abundance, myctophids not only directly contribute to carbon export, but also may exert top-down control on zooplankton communities, potentially affecting zooplankton-mediated carbon export.