Event Name/Location

MAR-ECO / Census of Marine Life Synthesis Meeting, Kristiansand, Norway, October 18-22, 2009

Document Type

Conference Proceeding

Publication Date

10-2009

Abstract

Few previous studies have focused specifically on the role of the mid-ocean ridges in the ecology of pelagic fishes. This study targets on a dominant nekton component of the mid- Atlantic mesopelagic ichthyofauna - the Stomiiformes - and their food resources including zooplankton and other nekton. Its main goal is to characterize the diets of several species of these midwater fish towards understanding the trophic pathways of the deep-pelagic nekton of the northern MAR. The study material was provided by the G. O. Sars 2004 Expedition under the International project MAR-ECO. On the lab fish were dissected and diet items were identified to the lowest taxonomical level possible. Preliminary results for 8 of the 12 species proposed for this study are presented. Amphipoda and Pteropoda seem to be important in Argyropelecus aculeatus feeding, while in Sternoptix diaphana diet amphipods are clearly the most common prey. Of the identifiable items in the guts of Maurolicus mulleri and Vinciguerria attenuata copepods constitute half of the occurrences but ostracods are also relevant. These four species show more planktivorous affinities when compared with the remaining species. Cyclothone microdon and Sigmops bathyphilum had the fewest identifiable items in the guts. In C. microdon while the stomachs were not completely empty it was very frequent to have a mass of unidentifiable jelly-like material. This may indicate that this species eats gelatinous plankton. Stomias boa reveals a piscivorous behaviour. Malacosteus niger is also a predator but occasionally eats copepods. Future work includes study of the remaining species: Sigmops elongatum, Argyropelecus hemigymnus, Borostomias antarcticus and Chauliodus sloani and more detailed analyses for all the target species, consisting on determination of prey biomass and feeding guilds, calculation of the fish daily ration and predation impact of the midwater fish assemblage on their prey in an attempt to design a food web model of the nekton community associated with the MAR.

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