Vertical distribution and population structure of copepods along the northern Mid-Atlantic Ridge

The Mid-Atlantic Ridge (MAR) between 40°N (Azores) and 63°N (Iceland) is the largest topographic feature in the North Atlantic Ocean. Despite generally limited surface production, there is evidence that the mid-ocean ridges are ecologically important for higher trophic levels relative to the surrounding open ocean. Vertical migrations of zooplankton are one of the primary mechanisms for the vertical transfer of carbon from surface waters to the deeper waters and sediments. The complicated topography of the MAR influences local and regional circulation patterns, which in turn are likely to affect the distribution of the zooplankton fauna. The crest of the MAR rises to 1000 m, thus intersecting the meso- and bathypelagic layers. In this paper we explore the vertical distribution and population structure of selected copepod species on the northern MAR, with the goal of better understanding the nature of the interactions between zooplankton and a mid-ocean ridge system. Zooplankton were sampled on the ridge from Iceland to the Azores (~60-41°N, 25-35°W) in June 2004. Depth stratified sampling revealed information on vertical distributions from surface down to 2500 m. The Subpolar Front (SPF) is the major biogeographic boundary in the studied area. Species with a wide vertical range also had a wide geographical distribution, occurring both north and south of the SPF. Several species were observed to change their vertical distributions along the transect, becoming deeper on the southern stations. Factors influencing vertical distributions are evaluated and relationships between zooplankton, water masses, and ridge topography are discusse

Abundance and productivity of the pelagic ecosystem along a transect across the northern Mid Atlantic Ridge in June 2003

A research cruise was conducted into the Irminger Sea west and southwest of Iceland on the Icelandic vessel Árni Friðriksson, from 4-30 June 2003, investigating redfish, Sebastes mentella, other pelagic fishes, zooplankton, phytoplankton and the hydrography of the area. Part of the cruise was devoted to a special study on the physical and chemical factors as well as the abundance of phytoplankton, meso- and macrozooplankton and planktivorous fish on a transect across the northern part of the Mid-Atlantic Ridge (MAR). This research is a part of the MAR-ECO project which aims to study the ecosystem associated with the northern MAR. In this paper we analyse the organisation of the pelagic ecosystem on the transect over the northern MAR, from phytoplankton to fish as apex predators. Keywords: MAR-ECO, Mid-Atlantic Ridge, environmental factors, phytoplankton, zooplankton, fish

Report on surveys of the distribution, abundance and migrations of the Norwegian spring-spawning herring, other pelagic fish and the environment of the Norwegian Sea and adjacent waters in late winter, spring and summer of 1997

The distribution and migrations of Norwegian spring spawning herring in the Norwegian Sea in the spring and summer of 1997 were mapped during 11 coordinated surveys carried out by Faroese, Icelandic, Norwegian, Russian and EU research vessels. After spawning on the banks off the Norwegian coast in February-March, the spent herring migrated out into the Norwegian Sea, and were recorded in international waters in April. In May, the younger part of the spawning stock was distributed in small schools or scattered layers at 25 - 100 m depth over wide areas in the central Norwegian Sea. Older and larger herring formed large schools, generally at 250 - 400 m depth, near the cold front along the eastern border of the Icelandic EEZ ( exclusive economic zone ). The total abundance of herring in the Norwegian Sea was estimated to be about 45 billion individuals or about 9 million tonnes in May