Algae (primary producers) use energy from the sun to transform inorganic compounds to energy-rich organic compounds.

All primary production – on land or in water – is affected by light, temperature, and accessibility of nutrients. Temperature is least important for productivity at sea. In winter (October–February) it is dark, and there is no primary production. When the light returns in February, production begins, initially only on the underside of the ice and along the ice edge. As spring progresses, algal blooms follow the ice edge northward into the Barents Sea. Eventually production is underway in the entire sea. Fridtjof Nansen was probably first to observe that algal blooms along the ice edge were considerably more dramatic than those in the free water column. This phenomenon, called the ‘ice edge effect’, arises because when the ice begins to melt, local light availability increases and a stable top layer of water forms. At the same time, nutrients are available in adequate amounts. The stability of the top layer also prevents the algae from sinking into the depths, where a lack of light prevents primary production. Under these favourable conditions, primary production supports high concentrations of zooplankton, which in turn attract large numbers of seabirds and marine mammals to the ice edge.

Although limited in time and space, this enormous spike in the supply of nutrients is utilised by all the animals that live in the surrounding seas. It also influences them in other ways. For example, most species have ‘timed’ their reproductive cycles to make optimal use of peak food accessibility. This is true also of organisms that live in and on the Arctic seabed. Many of the great whales graze in the Barents Sea, and numerous seabirds and fish species pass through it on their annual migrations. Bottom-dwelling species largely depend on the primary production that takes place in the water column and under the ice. Kelp forests rarely grow at depths greater than 30 metres. At 200 metres, all sunlight is gone. Animals living at greater depths must therefore rely on organic material that sinks to the bottom. If primary production in an area is high, herbivorous zooplankton in the underlying water column cannot make use of it all, and more will settle to the bottom. Areas so deep that they are dark year-round can nonetheless show distinct seasonal variations because they are influenced by a brief period of primary production.

The west coast of Svalbard has a relatively mild climate. This is due to the constant stream of mild air masses from the south, combined with warm Atlantic water flowing north along the west coast.

Heat comes from the Atlantic with the West Spitsbergen Current, which is part of the Gulf Stream system. The current contributes to Svalbard having a much warmer climate than other areas at the same latitude. Some of the warm, salty Atlantic water from the West Spitsbergen Current is diverted onto the continental shelf and into the fjords on Svalbard’s west coast. This means that heat is lost from the water that continues northward into the Arctic Sea. Heat lost along Svalbard’s coast ultimately warms the atmosphere above Svalbard, contributing to a warmer climate. In winter, the West Spitsbergen Current carries enough heat to melt ice about four metres thick if it comes in direct contact with the ice cover. Because of this, the west coast of Svalbard is essentially ice-free all year round. After passing Svalbard, the warm water masses sink below the colder, extremely stable layer of water at the surface; the cold surface water protects the Arctic Sea ice from melting.

Ocean currents from the south also help spread organisms northward – everything from tiny single-celled algae to big animals such as salmon and Atlantic cod. An example of the currents’ potential for bringing new species to Svalbard was the discovery of mussels at the mouth of Isfjorden in 2004. Currents had probably transported these molluscs from the coast of Norway a few years earlier. Few species find favourable conditions on land, but the benefits for those that manage to survive the winter are significant: abundant food in summer, no competitors, few predators, and ample opportunity to prepare for the next winter. Proximity to the ocean, the temperatures of the different currents, the presence and distribution of glaciers, and the archipelago’s topography all work together to provide a wide variety of living conditions on land in this inhospitable region.

Ice freezes and excludes salt, which ends up in the surrounding water. This happens throughout the shallow shelves around the Arctic Ocean and the Barents Sea. In Storfjorden, east of Spitsbergen, winter brings intense freezing of ice. There, heavy, cold, salty water has been observed flowing out along the bottom toward the deep basins of the Norwegian Sea and the Arctic Ocean. It has been estimated that Storfjorden contributes between 5% and 20% of total deep water formation on the shelves of the Arctic Ocean. Ice formation over the shallow shelves also helps maintain the cold, stable layer of water that protects the sea ice cover of the Arctic Ocean from the warm Atlantic water below.