THE SEA

In Svalbard there is a great difference between the biological production in the sea and on land. Whilst the land in Svalbard as a rule is very barren with little vegetation, the Barents Sea is one of the most productive seas in the world. First and foremost the production is connected to the phytoplankton in the open waters. The algae in the ice and the larger algae in the coastal areas are also important local contributors.

PRIMARY PRODUCTION

The Barents sea is one of the most productive oceans in the world. Photo Geir Johnsen

The algae (the primary producers) are able, with the aid of solar energy, to transform inorganic components into energy rich organic ones.

Both, in the sea and on land all primary production is affected by light, temperature and access to nutrition. Temperature is least important for the production in the sea. In winter (October-February) it is dark, at this time no primary production takes place. With the return of the light in February production begins again. At first it is limited to the underside of the ice and the ice-edge. During spring the algal bloom follows the edge of the ice as it retreats northwards in the Barents Sea. Gradually production begins to take place over the entire expanse of the Barents Sea. Fridtjof Nansen was probably the first to observe that the algal bloom along the edge of the ice was much greater than that out in the open waters. This is known as ‘The Ice-Edge Effect’. This is due to the availability of light and the stable upper layer of water that arises as the ice begins to melt. At the same time, an abundance of nutrition-rich salts is present. The stability of the upper layer of water prevents the algae from sinking down into the depths where there is too little light for primary production. The favourable production conditions mean that there will be large concentrations of zooplankton and therefore higher density of seabirds and marine mammals along the ice edge.

The limited and enormous supply of biological nutrients affects and is exploited by all animal life in these seas. Most species have, for example, ‘calculated and planned’ the reproduction period so that they are able to exploit the availability of food as much as possible. This also applies for all the bottom-dwelling organisms that are found in the seas in the Arctic. The Barents Sea is used as a grazing area for many of the large whales, a number of seabirds and several species of fish on their annual migrations in search of nutrition. The bottom fauna is, to a large degree, dependent on the primary production along the ice edge, both in the open waters and under the ice. The forests of sea tangle seldom stretch down deeper than 30 meters. At a depth of 200 meters almost all the sunlight is gone. The bottom fauna below 200 meters is, therefore, dependent on the organic material that sinks to the bottom. If the primary production is high in one area it becomes difficult for the plant-eating zooplankton in the open waters to exploit it all. More falls to the bottom. Areas that lie in almost total darkness year round have a clear seasonal variation since they are influenced by the cycles of primary production.

WARM AND COLD CURRENTS

The west coast of Svalbard has a relatively mild climate. This is due to the steady supply of mild air masses from the south as well as the North Atlantic Current which brings warm water up to the west coast of Spitsbergen.

The Atlantic water is known as the West Spitsbergen Current and is part of the Gulf Stream system. As a result we have a much warmer climate than other areas on corresponding latitude. The drain of warm salt Atlantic water from the West Spitsbergen Current reaching the continental shelf and the western fjords of Svalbard leads to a loss of heat for the waters on their way into the Arctic Ocean. This heat loss in the coastal areas around Svalbard is finally released into the atmosphere around Svalbard and contributes to a warmer climate. The West Spitsbergen Current holds enough heat during the winter to be able to melt around 4 meters of ice should it come into contact with the sheet of ice. As a result of this the west coast of Svalbard is generally free of ice the whole year. The cold surface waters protect the ice in the Arctic Ocean. The masses of water settle under the colder and very stable surface layer, which protects the ice from these large quantities of heat.

The ocean currents from the south also contribute to spreading of organisms. This applies equally to small single celled algae and to larger animals such as salmon and Atlantic cod. One example, of a potential new species that the ocean currents steadily bring with them to Svalbard, is the discovery of common mussels at the entrance to Isfjorden in 2004. These were probably brought with the ocean currents from the coast of Norway a few years before. Few species find favourable conditions on land. The gains for those species that survive the winter are great; the abundance of food in the summer, the lack of competitors, few predators and a rich foundation to prepare for the next winter. Closeness to the sea, the temperature of the different currents, the occurrence and extent of glaciers, as well as the lands height profile, work together and give the large variation in the conditions for life on land in these inhospitable areas.

Freezing and the following release of salt to the underlying water happen on the shallow continental shelfs in the Arctic Ocean and Barents Sea. In Storfjorden, on the east side of Spitsbergen, there occurs intense freezing during the winter. In this fjord there has been observed discharge of heavy, cold and salt waters along the bottom towards the deep basins in the Norwegian Sea and the Arctic Ocean. Storfjorden`s contribution to the deep-water formation is reckoned to be between 5% and 20% of the total production in the continental shelf areas in the Arctic Ocean. The ice production on the shallow continental shelf areas also contributes to maintaining the cold, stable layer of water that protects the ice cover in the Arctic Ocean against the underlying warm Atlantic water.

By scientists from UNIS and NP