Benthic diversity in the deep Norwegian Sea

The diversity of benthic organisms in the Norwegian Sea is higher than previously known. Ongoing projects reveal species and new knowledge. The first expedition set to explore deep sea diversity in this area was the “Norwegian North Atlantic Expedition 1876-1878”. This expedition was one of the first exploring deep sea diversity in the world. Not until the 1980’s new expeditions aimed at studying the benthic diversity. This is continued with the ongoing MAREANO programme. Polychaete worms from these expeditions are now studied to examine deep sea diversity as such, but also differences in diversity from shelf, slope and deep sea areas.

The Norwegian Sea, and the Nordic Seas. From Oug et al. 2010.
The Norwegian Sea, and the Nordic Seas. From Oug et al. 2010.

In the Norwegian Sea the Norwegian Sea Basin in the south and the Lofoten Basin in the north are areas with depths down to 4000 m. To the west the Norwegian Sea borders to the Greenland Sea and the Iceland Sea. Collectively this area is called the Nordic Seas. In oceanographical terms the Nordic Seas have different characteristics than the North Atlantic south of the ridge stretching from Scotland through the Faeroes and Iceland to the south tip of Greenland. This ridge represents a geographical barrier. Sea water temperatures in the Norwegian Sea below 600-800 m depth are colder than 0 °C. In shelf areas along the Norwegian coast water masses are characterised by an inflow of North Atlantic water across the Scotland-Greenland ridge.

Over the last years we have worked on polychaetes from selected families from the Norwegian Sea deeper than 600 m depth. Material for these studies is available from different expeditions, which most is deposited in collections of the University Museum of Bergen. The main material is large samples collected during 1980-1987. It was Torleiv Brattegard (University of Bergen) and Jon-Arne Sneli (Norwegian University of Science and Technology) who did this sampling, after an initiative from Brattegard. Other important samples available have its origin in the Norwegian North-Atlantic Expedition 1876-1878. In addition, the MAREANO programme provides newly sampled material from the coast to the deep sea.

Species collected in benthic environments collected from these expeditions and programmes are valuable, especially locations in the deep sea. Deep sea samples are expensive and time consuming to get, and are precious. Large quantities of specimens are valuable, and important, when studying diversity. Especially when describing new species. We need to study the variability of specimens representing new species to obtain a good comprehension of the identity of each species and how they differ from closely related species. In this project we have been lucky to have a large number of specimens available. This show how museum collections holding samples collected over centuries along with current sampling programs contribute to science and knowledge on biodiversity.

Since 2009 we have had projects going on to study selected groups of polychaetes. The main has been to study samples from deeper than 600 m depth, ranging to the deepest parts of the Norwegian Sea at 4000 m depth.


Oug E, Gjøsæter J, Anker-Nilssen T, Bakken T, Sneli J-A, Rueness J. 2010. Marine environments. In: Environmental conditions and impacts for red list species. Trondheim: Norwegian Biodiversity Information Centre. Pp 13-26.