The high Arctic: challenges for European biodiversity research

Research activities beside a calving glacier on the volcanic island of Javen Mayen (71^oN, 8^oE). Photo B. Gulliksen.

The area of interest for European marine biodiversity research extends northwards, beyond the Arctic circle, to approximately 80°N (Dinter, 2001). Seen within a European perspective, the Arctic contains a number of unique habitats and environmental conditions. Arctic marine biodiversity is characterised by a simplicity in upper trophic levels and highly specialised organisms. Such typical Arctic inhabitants are polar bears, seals such as ringed and bearded seals, walrus, whales such as the bowhead, narwhal and white whales and fish such as the polar cod. On the underside of floating ice are specialised communities of sympagic (ice-associated) flora and fauna, including filamentous ice algae and ice-amphipods. The pelagic and especially benthic systems are more complex in terms of both types and function of the organisms present. These environments share many general characteristics with more southerly latitudes, but also contain a variety of taxa that are not found anywhere else in Europe. Research in these areas therefore gives valuable data, but also presents a variety of challenges.

Arctic biodiversity research is by no means a new field, but developed hand-in-hand with Arctic exploration. Some of the earliest biodiversity data are 18th and 19th century records of fish and other organisms caught simply for food. However, by the late 19th and early 20th centuries, scientific expeditions were being carried out for oceanographic and biodiversity research, including both benthic and pelagic organisms. The most well known biodiversity publications of that period include those by M. Sars, G.O. Sars, Malmgren, Krøyer and Nansen. Today, many nations have a committed Arctic biodiversity research programme.

Ocean mixing 

The waters around Svalbard are a mixing area where warm Atlantic water from the south meets colder, Arctic water masses from the north. The precise position of the Polar Front, where these water masses meet, varies from year to year, but also is greatly influenced by cyclical circum-polar wind-driven circulation patterns (Proshutinsky & Johnson, 1997). During warm periods of cyclonic oceanic circulation in the central Arctic, there is thinner ice in the Barents Sea and a greater influx of Atlantic water from the south relative to anti-cyclonic periods, where Arctic water extends further southwards (Polyakov et al., 1999). These fluctuations cause marked changes in the Polar Front and the southern extent of sea ice, which in turn affects productivity and a whole series of biological processes in the water masses and sea floor. The biogeographic distribution of planktonic and benthic organisms varies with these oceanographic fluctuations. Therefore, biodiversity and biogeographic analyses can offer a means of mapping the relative distribution of the various water masses in the Arctic.

Coastal systems 

Coastal areas are highly influenced by glacial processes. Along the Norwegian coastline, most fjörds have deep basins, often with very shallow sills at their mouths. Despite this, Arctic Norwegian fjörds usually are well oxygenated down to the bottom layers all year round. This contrasts with more southerly fjörds, which often have a naturally low oxygen content. From the very north of Norway, above 70^oN and beyond, most fjörds do not have a sill and conditions at their mouths resemble the open sea. At the same time, there are complex systems of islands, skerries and side-fjörds making both the coastline and its resident biodiversity extremely heterogeneous.

Svalbard 

Along the Svalbard coastline, 77^oN to more than 80^oN, most fjörds have actively calving tidal glaciers in their inner parts. This creates a very dynamic marine environment, with often dramatic gradients in temperature, salinity and sedimentation. Most glaciers are retreating, with intermittent periods of surging. Net glacial retreat can be more than a metre per year and in some cases is up to or more than 100 metres per year (see Svendsen, 2002), such that new marine areas continually are appearing. Therefore, colonisation studies offer a means of experiencing and understanding post-glacial events that took place many thousands of years ago in more southerly areas. The marine fauna and flora are exposed to winter darkness, during which time little or no production occurs, alternating with summer periods of 24-hour daylight, during which time intensive production surges occur. Ice-scouring along the shore and gouging by ice-bergs also are regular occurrences. These strong gradients in physical conditions are reflected in strong gradients in biodiversity, from sparse assemblages of organisms that tolerate unstable conditions close to the glacier to rich faunal and floral assemblages in the outer parts. 

The underside of floating ice, showing long strands of ice-algae, mostly comprising Melosira arctica. Photo D. Piepenburg.

An interesting phenomenon occurs in many Svalbard fjörds, particularly along the western shores. Above the water, the environment looks very Arctic indeed, with sub-zero temperatures and calving glaciers. Accordingly, the above-water biodiversity members, such as polar bears and walrus, are typically Arctic. However, in the pelagic and particularly the benthic environments, there often is a dominance of Atlantic taxa, transported there by the northernmost extent of the Gulf Stream. In the northern and eastern parts of Svalbard, the Arctic water influence is dominant. 

To further the understanding of this complex environment of contrasts, changes and mixtures, a review of the physical and biological conditions of Kongsfjorden (78°55'N, 11°56'E) recently was compiled (Svendsen et al., 2002, Hop et al., 2002). Kongsfjorden also is the northernmost of the key BIOMARE sites for biodiversity research.

Research 

The questions that Arctic biodiversity research can ask are many. Hypotheses and models may be made of the effects of climatic changes on Arctic processes. Will a shift to a warmer climate regime decrease the role of ice-algae and planktonic organisms in the marine food web and increase the dependence on benthos as a food source? Can temporal data series of benthic organisms tell us about fluctuations in different water masses? Because polar areas are subject to atmospheric deposition of contaminants released from southern areas, effect studies on Arctic organisms are an important tool in encouraging the global population to reduce the release of persistent contaminants into the atmosphere. These and other biodiversity issues are studied in Tromsø and Svalbard by institutes including Akvaplan-niva, the University of Tromsø, the Norwegian Polar Institute, the Norwegian Institute of Fisheries and Aquaculture Research, the Norwegian Institute for Nature Research and the University Courses on Svalbard. Studies of faunal and floral structure, function and biogeography are carried out by numerous institutes both in Norway and internationally.

For each question answered, however, many further issues arise, some of which cannot yet be answered. For example, because of the practical difficulties of sampling through ice-cover, for many areas of biodiversity, there exists almost no winter data at all. The logistics of Arctic research often limits the scope of investigations, which severely limits both the statistical power and representativity of analyses. Therein lie many of the future challenges for Arctic biodiversity research.

The Arctic represents the very northern extent of European marine waters. It is important to document and continue research into its unique fauna and flora, together with the physical environment that influences it. One of the major achievements of the BIOMARE concerted action has been to bring researchers from all over Europe together and to consider the particular challenges and benefits of the different parts of European waters. From the Arctic to the Mediterranean, the Black Sea to the Azores, each area provides unique and valuable information. Developing common goals and common strategies produces integrated European marine biodiversity research that will be better equipped to answer large-scale environmental and biological questions both now and in the future.

References

Dinter, W. P. 2001. Biogeography of the OSPAR maritime area. - BfN-Schriftenvertrieb in Landwirtschaftsverlag.

Hop, H., T. Pearson, E. Nøst Hegseth, K.M. Kovacs, C. Wiencke, S. Kwasniewski, K. Eiane, F. Mehlum, B. Gulliksen, M. Wlodarska-Kowalczuk, C. Lydersen, J.M. Weslawski, S. Cochrane, G.W. Gabrielsen, R.J.G. Leakey, O.J. Lønne, M. Zajaczkowski, S. Falk-Petersen , M. Kendall, S.-Å. Wängberg, K. Bischof, A.Y. Voronkov, N.A. Kovaltchouk, J. Wiktor, M. Poltermann, G. di Prisco, C. Papucci & S. Gerland 2002. The marine ecosystem of Kongsfjorden, Svalbard. - Polar Research 21(1): 167-208.

Polyakov, I.V., A.Y. Proshutinsky & M.A. Johnson 1999. Seasonal cycles in two regimes of Arctic climate. - Journal of Geophysical Research 104 (C11): 25,761-25,788.

Proshutinsky, A. & M. Johnson 1997. Two circulation regimes of the wind-driven Arctic Ocean. Journal of Geophysical Research 102:12493-12512.

Svendsen, H., A. Beszczynska-Møller, J.O. Hagen, B. Lefauconnier, V. Tverberg, S. Gerland, J.B. Ørbæk, K. Bischof, C. Papucci, M. Zajaczkowski, R. Azzolini, O. Bruland, C. Wiencke, J.-G. Winther & W. Dallmann 2002. The physical environment of Kongsfjorden-Krossfjorden, an Arctic fjord system in Svalbard. - Polar Research 21: 133-166.