The Norwegian Sea is a transition zone between boreal and Arctic conditions, and thus contains flora and fauna characteristic of both climatic regions. The southern limit of many Arctic species runs through the North Cape, Iceland, and the center of the Norwegian Sea, while the northern limit of boreal species lies near the borders of the Greenland Sea with the Norwegian Sea and Barents Sea; that is, these areas overlap. Some species like the scallop Chlamys islandica and capelin tend to occupy this area between the Atlantic and Arctic Oceans.
Plankton and sea bottom organisms
Most of the aquatic life in the Norwegian Sea is concentrated in the upper layers. Estimates for the entire North Atlantic are that only 2% of biomass is produced at depths below 1,000 metres and only 1.2% occurs near the sea floor.
The blooming of the phytoplankton is dominated by chlorophyll and peaks around 20 May. The major phytoplankton forms are diatoms, in particular the genus Thalassiosira and Chaetoceros. After the spring bloom the haptophytes of the genus Phaecocystis pouchetti become dominant.
Hyperiidea Shrimp Pandalus borealis Lophelia pertusa
Zooplankton is mostly represented by the copepods Calanus finmarchicus and Calanus hyperboreus, where the former occurs about four times more often than the latter and is mostly found in the Atlantic streams, whereas C. hyperboreus dominates the Arctic waters; they are the main diet of most marine predators. The most important krill species are Meganyctiphanes norvegica, Thyssanoessa inermis, and Thyssanoessa longicaudata. In contrast to the Greenland Sea, there is a significant presence of calcareous plankton (Coccolithophore and Globigerinida) in the Norwegian Sea.Plankton production strongly fluctuates between years. For example, C. finmarchicus yield was 28 g/m² (dry weight) in 1995 and only 8 g/m² in 1997; this correspondingly affected the population of all its predators.
Shrimp of the species Pandalus borealis play an important role in the diet of fish, particularly cod and blue whiting, and mostly occur at depths between 200 and 300 metres. A special feature of the Norwegian Sea is extensive coral reefs of Lophelia pertusa, which provide shelter to various fish species. Although these corals are widespread in many peripheral areas of the North Atlantic, they never reach such amounts and concentrations as at the Norwegian continental slopes. However, they are at risk due to increasing trawling, which mechanically destroys the coral reefs.