1.3.6 Current status of freshwater systems in Svalbard
There has recently been published a summary of the available knowledge of freshwater systems in Svalbard. With permission from the authors (John E. Brittain, Ann Kristin Schartau and Martin-A. Svenning), we present the English summary. Pictures are added by us. The full report is in Norwegian, and available here (link).
Freshwater systems on the Svalbard archipelago are vulnerable to several threats such as climate change, eutrophication, local and global pollution, physical changes, harvesting and other human activities. However, our knowledge of Svalbard’s freshwater ecosystems is lacking, and the aim of this report is to describe the status and influences on biological diversity in addition to proposing appropriate localities and methods for future monitoring.
Shallow pools and small lakes formed by permafrost dominate the freshwaters. There are also about a couple of hundred lakes as well as many rivers and streams that only flow 2-4 months a year on account of the permafrost. Most of the water bodies are on the western parts of the archipelago as most of the eastern areas are covered by glaciers. Most of Svalbard was covered in ice during the last Ice Age and represents some of the most isolated islands in the Polar Ocean. Immigration of freshwater organisms has therefore taken place after the Ice Age. The isolation in combination with the High Arctic climate has led to low biological diversity and a dominance of cold adapted organisms.
Glaciers account for 50% of the runoff, but there are many small watercourses, especially along the coast that have precipitation and/or snowmelt as their source. On account of permafrost groundwater is less common, although there are streams that are influenced by groundwater. There are also a few warm springs, especially in Bockfjorden, north on Spitsbergen. Glacial rivers usually have high discharge, very low temperatures and carry high sediment loads during the melt season, while other watercourses have clearer waters and higher temperatures. Most watercourses are poor in nutrients, although those under bird cliffs have higher concentrations of nutrients. Periphyton, especially diatoms and blue-green bacteria, as well as aquatic mosses are common in running waters. The fauna in running water is dominated by Chironomidae, especially the subfamily Diamesinae with many cold-water species, although in non-glacial streams the subfamily Orthocladiinae are abundant.
Lakes on Svalbard are usually very cold and ice covered 9-10 months a year. The ice is thick, but often relatively transparent because of little snow, such that much of primary production occurs under the ice. Somewhat simplified lakes can be divided into two main types. Glacial lakes have glaciers in their catchment and glacial runoff in summer leads to very low temperatures and a Secchi depth of only a few centimetres. Clear water lakes are not, at least to a limited extent, influenced by glacial runoff and have higher summer temperatures and a Secchi depth of several metres. Shallow pools that are not glacially influenced often have relatively high temperatures in summer, but many freeze to the bottom in winter. On account of sedimentary rocks many lakes have a very high ionic content. Small tundra ponds can also have a high content of various salts owing to their closeness to the sea, as well as high phosphorous concentrations on account of high densities of geese that are on Svalbard during summer. The phytoplankton community varies considerably, but Chlorophyta, Chrysophyceae and Bacillariophyceae are common. Charophyta have been recorded in Trollkjeldane, one of the warm springs. Macrophytes have been poorly studied, but they are likely to be rare. Some lakes may have mosses. Svalbard has a relatively rich fauna of rotifers and crustaceans and most species have a circumpolar distribution. Among the insects, chironomids dominate, but no Mollusca have been recorded. The most northerly freshwater fish, Arctic charr, is the sole fish species that lives and reproduces on Svalbard. The charr occur in two main forms, resident that spend their whole life in a lake and anadromous that undertake food migrations out to sea during the summer.
Brittain JE, Schartau AK & Svenning M-A (2020) Biologiske mangfold i ferskvann på Svalbard: kunnskapsgrunnlag, påvirkninger og forslag til framtidig overvåking. Vol. Rapport nr. 13. Norges vassdrags- og energidirektorat, Oslo.