Fish larval patterns across the Reykjanes Ridge

Abstract

Fish larvae and hydrography were surveyed in summer 2005 in the upper 500 m from the Iceland Basin across the Reykjanes Ridge [as part of the Mid-Atlantic Ridge (MAR)], and into the Irminger Sea. Fish larval abundance was highest in the Iceland Basin, followed by the eastern slope of the ridge. Among 22 identified taxa, larvae of mesopelagic boreal and boreal–subarctic species prevailed, with Maurolicus muelleri contributing 80.9% to the total abundance, followed by Benthosema glaciale and Protomyctophum arcticum. Four subtropical species were first recorded for these latitudes, linked with the positive sea surface temperature anomaly encountered. Furthermore, larvae of demersal species were caught, mainly above the ridge and eastern slope of the Greenland Basin, enhancing species richness there. Changes in fish larval abundances, species richness and vertical distributions of larvae coincided with hydrographic fronts and bottom topography. MAR bottom topography guides currents in midwater. The role of these and surface currents for larval dispersal is discussed.

Keywords:

• CTD hydrography
• currents
• fish larval communities
• Reykjanes Ridge

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

Acknowledgments

We thank the crew and shipmates during Walther Herwig cruise 276 for excellent working conditions and a pleasant cruise. Work was supported through MAR-ECO grant 10331-3 (HF). D. Gloe (Kiel) provided the synoptic horizontal temperature sections from the Irminger Sea.

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