Gelatinous zooplankton on the Mid-Atlantic Ridge, Distribution patterns of trawl-collected planktonic cnidarians

Abstract

The Mid-Atlantic Ridge (MAR) between 40˚N (Azores) and 63˚N (Iceland) is the largest topographic feature in the North Atlantic Ocean. However, the fauna and ecological significance of mid-ocean ridges has remained poorly understood. This is especially true for the morphologically fragile gelatinous fauna, which has been poorly studied due to methodological constraints. From 4 June to 5 August 2004 the G.O. Sars expedition along the northern Mid-Atlantic Ridge was a major field study initiative under the MAR-ECO project (www.mar-eco.no), a field project under the Census of Marine Life. An extensive sampling program for pelagic fauna was performed, using a suite of nets, trawls, UVP and ROV observations. Here we present the composition, abundance and vertical distribution of medusae and siphonophores collected with pelagic midwater trawls along the northern Mid-Atlantic Ridge (MAR) June 2004