Due to the low temperatures and low precipitation, lake ice on Svalbard is very compact and transparent, and little snow settles on it. The relatively clear black ice, together with low snowfall, means that a lot of the light penetrates through and contributes to relatively high primary production under the ice.
In lakes with catchments containing significant glaciers (glacial lakes), increased summer solar radiation causes large volumes of glacial sediments to be transported out into the lakes.
Annual production in Svalbard lakes varies strongly with climatic conditions, primarily temperature and snowfall. However, it is the lack of nutrients, rather than sunlight and temperature, that is considered to be the most significant single factor limiting primary production in Arctic lakes. The exception is lakes that receive large quantities of nutrients from external sources, such as seabirds nesting in the lakes’ catchment basins
Svalbard’s extreme isolation, in combination with its Arctic climate, has produced freshwater sites with very few species of plankton and benthic animals. Char is the only freshwater fish. Stoneflies, dragonflies, black flies and predaceous diving beetles are among the species found in most of the lakes of Northern Norway, but which have not yet been observed in Svalbard.
The dominant bodies of water are shallow (<2 m) ponds and small lakes created by permafrost. These often have a high production of insects and crustaceans, may be significant biotopes for birds, and are highly vulnerable to permafrost thawing. These permafrost-dammed pools do not normally support fish since they freeze through to the bottom in winter, whereas Arctic char live in effectively all the lakes on Svalbard below the marine limit that do not freeze through (are deeper than 2 m).