Cephalopods of the northern Mid-Atlantic Ridge

Abstract

A two-leg cruise of R/V G. O. Sars in summer of 2004 along the Mid-Atlantic Ridge explored the diversity and distribution patterns of pelagic and non-hydrothermal bottom communities in the vicinity of the northern Mid-Atlantic Ridge. In total, 1295 cephalopods were caught, representing 56 species. Differences in species composition and size were apparent among the various types of trawls used. The Aakra trawl and bottom trawl caught the largest numbers of species (38 and 34, respectively); size of cephalopods was directly related to the size of the net. Many more species were caught in the southern part of the study area than farther north. The most abundant species was Gonatus steenstrupi, found mostly in the northern part of the study area. A few abundant species, such as Mastigoteuthis agassizii, were found throughout the region, with no clear indication that their northern or southern distributional limits occur within the area sampled. Several benthic and one pelagic species, all taken in small numbers, were captured only in the region of the Charlie Gibbs Fracture Zone. We found many species at very low numbers (i.e. 37 species with <10 specimens in all gear types combined).

Keywords:

• Bathypelagic
• deep sea
• distribution
• epibenthic
• mesopelagic
• octopods
• squids
• trawling-gear comparisons
• zoogeography

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Acknowledgements

We thank the participants in the MAR-ECO project, and especially Odd Aksel Bergstad, without whom this research could not have been accomplished. We also thank the captain and crew of the R/V G. O. SARS for making both legs of the cruise pleasant and productive. Annie Lindgren assisted us with taxonomic difficulties by analyses of DNA. Martin Collins helped greatly with the difficult identification of cirrate octopods.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark