Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

Ecology of the Midwater Fish Family Melamphaidae Over the Mid-Atlantic Ridge

Event Name/Location

International Council for the Exploration of the Sea (ICES) Annual Science Conference, Halifax, Canada, September 22-26, 2008

Presentation Date

9-2008

Document Type

Conference Proceeding

ORCID ID

0000-0002-5280-7071

Keywords

Mid-Atlantic Ridge, MAR-ECO, Melamphaidae, Relative abundance, Species composition, Mesopelagic, Bathypelagic

Description

The 2004 MAR-ECO expedition over the northern Mid-Atlantic Ridge aimed, in part, to describe the overlying pelagic macro- and megafauna and their roles in mid-ocean ecosystems. The month-long cruise sampled portions of the ridge between Iceland and the Azores at 36 stations. One of the dominant pelagic fish families along the sampled segment of the ridge was the family Melamphaidae. Melamphaid species abundance and biomass data were examined with respect to depth, altitude above the ridge, and local area (Reykjanes Ridge, Charlie-Gibbs Fracture Zone, Faraday Seamount Zone or Azorean Zone). Highest species numbers and abundances occurred at depths between 750-1500 m. Some individuals were found above 200 m, setting new minimum depth of occurrence records for the family. Large-scale shifts in species composition were observed relative physical oceanographic features; for example, the genus Scopelogadus shifted from S. beanii dominance north of the Subpolar Front to S. m. mizolepis southward. Trawls less than 400 m above the bottom depth showed a trend towards higher melamphaid abundance and biomass in southern stations than northern stations. Given the high relative abundance in this survey, and their reported consumption of gelatinous prey, the Melamphaidae may represent a previously unknown trophic linkage between fishes and gelata in bathypelagic systems. Results of ongoing trophic analyses will be presented to assess the magnitude of this linkage along the northern Mid-Atlantic Ridge.

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