Svalbard – marine areas
Five marine ecosystem types on Svalbard are threatened, all due to climate change. Polar sea-ice has been assigned to the highest category and is assessed as Critically Endangered due to a significant decline.
- Natural conditions and marine ecosystem types of Svalbard
- Assessment entities
- Existing knowledge
- Key impact factors
- Jan Mayen
- Group of experts
The current assessments comprise all marine ecosystem types in the coastal and fjord areas of Svalbard, including Bjørnøya (Bear Island) and the island of Hopen. The area covered by the assessments extends to the territorial border (12 nautical miles from land), which corresponds to the area under Norwegian jurisdiction. The assessments include Polar sea-ice I2, Circulating fjord, estuary, lagoon and rock pool waterbody H2, Euphotic marine rock M1, Aphotic marine rock M2, Littoral rock M3, Euphotic marine sediment M4, Aphotic marine sediment M5, Tidal rock pool seabed M9, and Marine cave and overhang M10. The marine ecosystems of Svalbard differ substantially from Norwegian coastal areas and the continental shelf, and a number of major and minor ecosystem types do not exist there. Furthermore, many minor types are less well-delimited, and some do not fit into the current NiN-system (version 2). In cases concerning minor types which are ambiguous or poorly delimited, and which could be under threat, there is scope for adopting a pragmatic approach.
At the major type level, Polar sea-ice (I2) is assessed as Critically Endangered CR due to a significant decline in occurrence (distribution, thickness). The remaining major types are assessed as being of Least Concern LC. Under the major types H2, M1, M3 and M4, eight minor types have been singled out and assessed. Some of these types are combinations in accordance with selection criteria 1.2 (few occurrences) or 1.3 (qualitatively different impact factor than the major type and which can result in a higher Red List category). Four of these eight types are assessed as Endangered EN or Vulnerable VU, and four are placed in the category Data Deficient DD due to insufficient information.
Natural conditions and marine ecosystem types of Svalbard
Under the terms of the Svalbard Treaty, Svalbard comprises the large islands of Spitsbergen and Nordaustlandet, all the surrounding islands, as well as Bjørnøya (Bear Island) and the island of Hopen. These have a combined area of approximately 63 000 km2. Svalbard is bordered in the west by the Greenland Sea (north-eastern Atlantic Ocean), in the north by the Arctic Ocean, and in the east and south by the Barents Sea. The climate is arctic but there are significant differences between Bjørnøya and the west coast of Spitsbergen, which are influenced by northward flowing mild Atlantic waters (the West Spitsbergen Current which is a branch of the Gulf Stream), and the areas in the north and east which are influenced by extremely cold waters from the Arctic Ocean which flow southward. In the west and north of Spitsbergen and Nordaustlandet in particular, there are many large and deep fjords that carve their way inland. As much as 60 % of the land mass is covered by ice. In winter most of the fjords and ocean areas in the north and east freeze over, although there are large variations from year to year. The areas in the north and east are influenced moreover by multi-year ice and pack ice from the Arctic Basin. Bjørnøya lies roughly halfway between Norway and Spitsbergen. There are no fjords on Bjørnoya and the coastline is mostly steep and exposed to waves.
The current assessment comprises marine ecosystems in the fjords and coastal areas of Svalbard. Within these areas there are relatively deep waters both on Svalbard's shelf and in the fjords. Isfjorden fjord has for example depths close to 400 m. This indicates that both shallow and deep ecosystem types are included in the assessments.
Jan Mayen is a part of the Kingdom of Norway and not included in the Svalbard Treaty. Marine ecosystems on Jan Mayen are not included in the current Red List assessment but the natural conditions are described in a separate section below.
The coastal areas of Svalbard are to a large degree characterised by two factors that have little significance on the Norwegian coast; ice and discharges of glacial mud. The sea-ice on Svalbard can be divided into three types: annual ice that is formed in the fjords; multi-year ice in the Arctic Ocean and the Barents Sea; and annual ice in the Arctic Ocean and the Barents Sea. Annual ice in the fjords is generally quite stable, with few ice floes, and an even surface. The maximum distribution of ice in the fjords usually occurs in the period from April – June. Annual ice in the Arctic Ocean and Barents Sea forms between channels in the ice and along the edges of the multi-year ice. It can also form channels in the ice and pressure ridges. Multi-year ice (polar sea-ice) is several metres thick (3 – 5 m) and to a large degree is broken up in ice floes that can also form pressure ridges. In the 1980s and 90s it was estimated that 50-90 % of the ice was older than five years. Both annual ice and multi-year ice have decreased considerably in recent years. While the majority of fjords on Spitsbergen froze over each winter in the 1970s and 80s, and annual ice could remain for the entire year in the northeast; in recent years the largest fjords in the the west have generally been ice-free. Satellite observations since 1979 indicate that there has been a decline in multi-year ice of around 30 %. In addition to sea-ice, the fjords are exposed to ice bergs that calve from glaciers.
Discharges of glacial mud occur in the summer half-year and are transported with meltwater from glaciers and precipitation over land. These discharges lead to reduced visibility in the fjords; in the most exposed areas down to some few centimetres, at the same time as particles are deposited on the seafloor where they can form a layer of several centimetres. The discharge of glacial mud is a dynamic and predominantly seasonal impact factor on the flora and fauna. Particles which are deposited on marine rock substrate areas can be washed away with currents and/or waves, dependent on the depth and degree of exposure to water currents and waves.
Marine ecosystem types on Svalbard differ in several respects from the ecosystem types on the Norwegian mainland and in the ocean areas beyond the Norwegian coast. For example, the major types Coral reef seabed M6, Seagrass bed M7, Tidal swamp M8, Anoxic marine sediment M13 and Anoxic marine waterbody H3 are not represented. Within the commonly occurring major types of marine rock, marine sediment and marine waterbody systems there are many minor types that do not exist due to the special environmental conditions created by factors such as low temperature, ice, and particle sedimentation. Examples of this are found under Littoral rock M3 where it is most likely that there are only a few minor ecosystem types and where brackish types probably do not exist. Correspondingly there appear to be many minor types under Euphotic marine rock M1 and Euphotic marine sediment M4 which do not exist. With regard to the littoral zone and very shallow waters, four characteristic organism communities on Svalbard are described; Fucus-Balanus communities on marine rock substrates and in rocky littoral zones; Gammarus (Amphipoda) communities on sheltered shorelines; Onisimus (Amphipoda) communities on mudflats with brackish water in estuaries and lagoons, and Oligochaeta communities on exposed sand and gravel substrate (Weslawski et al. 1993, Moe et al. 2000, Ravolainen et al. 2018).
With regard to the assessment entities, it is a challenge that the delimitation of ecosystem types using the environmental gradients (LECs) in NiN2 is based on the ecosystem types found on the Norwegian mainland. In addition to the fact that many minor types do not exist on Svalbard, a consequence of this is that a number of minor types are less well-delimited and in many cases ambiguous. An example is Ice-scoured boulders M1-29 which on Svalbard also needs to be interpreted so as to include crags and rock faces. Likewise there are ecosystem types on Svalbard that do not fit into the current NiN system (version 2.0). In cases with ambiguous or poorly delimited minor types that could be under threat, there is scope for adopting a pragmatic approach, e.g. by suggesting adjustments to the segmentation of relevant LECs. Examples include Arctic fjord waterbody which has been defined by adjusting segments in the LEC "SA" (marine salinity: salt-enriched), and Arctic lagoons which have been placed under the major type Circulating fjord, estuary, lagoon and rock pool waterbody H2 but which differ in size, formation, and environmental conditions from the ecosystem types on the mainland.
At the major type level a total of nine major types are assessed. These are Circulating fjord, estuary, lagoon and rock pool waterbody H2, Polar sea-ice I2, Euphotic marine rock M1, Aphotic marine rock M2, Littoral rock M3, Euphotic marine sediment M4, Aphotic marine sediment M5, Tidal rock pool seabed M9 and Marine cave and overhang M10. All major types that comprise seabed systems can be found across Svalbard in its entirety, whilst Circulating fjord, estuary, lagoon and rock pool waterbody H2 is primarily found on Spitsbergen, and Polar sea-ice I2 is particularly frequent in the areas in the north and east. In strict terms Oceanic waterbody H1 also exists within the territorial border surrounding Svalbard, but it is a very narrow zone that is unnatural to assess separately from the general assessment of the ocean areas and is therefore not included here.
At the minor type level the following have been created: three assessment entities of type 1.2 (few occurrences) and five assessment entities of type 1.3 (an impact factor that is qualitatively different from the major type and which can result in a higher Red List category than that which applies to the major type). The three entities of type 1.2 are Arctic fjord waterbody under the major type H2, Sheltered brackish littoral rock under the major type M3, and Shell sand substrate under the major type M4. The assessment entities of type 1.3 are Ice-scoured boulders under major type M1 and Ice-scoured littoral rock under the major type M3 where ice-scour is a factor for both; Brackish sand and gravel substrate under major type M4 where erosion due to climate change is a factor; Maerl beds under major type M4 where ocean acidification is a factor; and Estuarine inlet and lagoon under major type H2 where climate change is a factor.
Arctic fjord waterbody H2-2, H2-3, H2-7, H2-8 refers to cold water bodies in sill fjords where the basin waters are characterised by very low temperatures (minimum temperature -1.86° C at 35 ppt but which can fall below – 2 ° C with higher salinity) and higher salinity than in the waters above the sill basin. Water renewal ("bottom water formation") occurs with the local formation of very cold and salty water (brine) at the surface during ice formation. This heavy, hypersaline water sinks and forms bottom water. The oxygen conditions are good as a result of frequent water renewal and because cold water can contain a large amount of oxygen. The fjord basins are characterised by a benthic community with high species richness and often a high biomass, as well as a characteristic element of high Arctic species (Weslawski 2010, Ravolainen et al. 2018). Arctic fjord waterbodies can be found in Magdalenefjorden, Wijdefjorden and Billefjorden among others. It is assumed that the number of 10 x 10 km grid cells with Arctic fjord waterbodies is less than 20 on Svalbard.
Sheltered brackish littoral rock M3-11, M3-12, M3-13, M3-18 can be found in river outlets where discharges of freshwater create an estuarine area with reduced salinity. In the meantime it is uncertain whether the ecosystem type exists on Svalbard. This is due to large discharges of terrigenous matter which form a sediment substrate in the river outlet, at the same time as there is a significant probability of ice-scour on rock substrate. If the ecosystem type exists, which can be the case at the outlet of small watercourses in sheltered areas, it is expected that these will be rare. It is assumed that the number of 10 x 10 km grid cells with possible occurrences of the ecosystem type will not exceed 20.
Shell sand substrates M4-10, M4-19, M4-37 are not common on Svalbard. It is likely that smaller occurrences could exist in areas with maerl beds which are assumed to be the most important source material of shell sand along with the shells of snails and bivalves (mussels, scallops etc.), and the skeletons of sea urchins and bryozoans. The delimitation with the ecosystem type maerl beds is therefore somewhat ambiguous. In areas without a significant influence of currents, it is assumed that possible occurrences are occasionally covered by terrigenous sedimentation, especially during the meltwater season. Shell sand substrates will be threatened by ocean acidification which can lead to a future loss of calcareous organisms and the bottom substrates that these create. Shell sand substrates are selected as an assessment entity of type 1.2 as it is presumed that only a few, patchy occurrences can exist on Svalbard.
Ice-scoured boulders M1-29 and Ice-scoured littoral rock M3-19 consist of marine rock substrates in shallow waters and the littoral zone that are exposed to annual ice-scour. Ice-scour is caused by drifting polar sea-ice (multi-year ice in coastal areas in the north and east), icebergs calving from glaciers (marine-terminating glaciers) and ice that forms each year (annual ice in fjords, coastal areas and between floes of multi-year ice). Ice-scour is generally deeper on the north side of Svalbard, due to ice drift and discharges of multi-year ice from the north and north-east. The multi-year ice is usually thicker than the annual ice. Both annual ice and multi-year ice become compacted along the coast by wind and water currents and deeply scour the seabed, not uncommonly down to depths of approximately 10 m along the northernmost islands (Sjuøyene). The ice does not gouge as deeply in fjords that only have annual ice. Ice from glaciers has little significance for flora and fauna in the broader context, but ice-scour tracks on the sea bed due to icebergs are not infrequently observed near glaciers, also at depths greater than 10 m. Ice-scoured rock substrates are characterised by clean surfaces without organisms, but sessile species can survive in crevices, hollows, and cavities between cobbles on boulder substrates. Ice-scoured substrates are in decline due to reduced polar sea-ice and less annual ice in the fjords of Svalbard.
Climate change is a factor for the assessment entity Brackish sand and gravel substrate M4-38, M4-40. Brackish sand and gravel substrate includes larger flat, sandy beaches and mudflats in river outlets that dry out at low tide (Onisimus community sensu Weslawski et al. 1993). These areas freeze in winter, but temperature increases due to climate change will lead to less ice formation. This provides an opportunity for perennial species to become established, while the areas become simultaneously vulnerable, and more exposed to erosion from waves at times of the year with rough weather conditions (Weslawski et al. 2011, Ravolainen et al. 2018). Increased freshwater discharges in the summer half-year can also lead to increased erosion of dried-out surfaces.
Ocean acidification is a factor for the assessment entity Maerl beds M4-11 and M4-20. Maerl beds are occurrences of coralline algae (red algae) that grow on sand, mud or gravel in areas with moderately strong water movement, but protected from powerful waves. On the coast of Svalbard the species Lithothamnion glaciale and Phytmatolithon tenue are the most frequent examples (Teichert 2013). Maerl beds are known to exist in Floskjæret, Krossfjorden, Moselbukta, Nordkappbukta, Rijpfjorden, Duvefjorden and around the Sjuøyene islands (Teichert 2013, Gulliksen pers. comm.). Ocean acidification is thought to be severe in the Far North. Brodie et al. (2014) estimate that in 2100 there will be a significant loss of dead maerl (gravel as well as living algae) due to lower pH-values in the ocean, but there is considerable uncertainty associated with this and the degree to which the species will be able to adapt to gradual changes (AMAP2018).
Artic lagoons are a characteristic ecosystem type on Svalbard that are defined as being shallow, saline waterbodies that are completely or partially separated from the sea by a barrier of sediments (Haug and Myhre 2016). The salinity varies according to the degree of freshwater discharge and can vary considerably throughout the year. Wind and currents contribute to the waterbodies often being homogenous and with little separation of layers, in contrast to the situation in estuarine inlets which have permanent contact with the ocean. Large parts of the water masses in Arctic lagoons can freeze solid during winter. There is very little knowledge about the organism communities in Svalbard's lagoons, but in general, Arctic lagoons are often characterised by pioneer communities with a small number of tolerant and robust species (Haug and Myhre 2016). The lagoons will be threatened by climate change in the future, both as a result of changes in freshwater discharges, contact with the sea and processes that can influence the sediments that delineate the lagoons.
In general, the knowledge about ecosystem types on Svalbard is deficient. The areas which have been researched best are Bjørnøya (Bear Island), and the west coast of Spitsbergen, especially the fjord areas at Hornsund, Isfjorden and Kongsfjorden where scientific research has been conducted since the 1800s. The areas on the east side of Spitsbergen and around Nordaustlandet are much less familiar. There are still ocean areas that have not been adequately surveyed and for which detailed nautical charts are unavailable. Information on bathymetry and seabed types is therefore of varying quality and coverage. For ecosystem types that require registration in the field, either by taking samples or direct observation, the information is scattered and patchy. This applies in particular to areas that are inaccessible for research vessels due to the unavailability of nautical charts. This is also an important reason for the significant uncertainty regarding the existence of a number of ecosystem types (minor types), apart from those that are most common, or where the delimitation of these when divided into minor types is poor.
With regard to determining ecosystem type areas, there is reasonably good data available for the total area of certain ecosystem types that are visible from the surface, such as polar sea-ice, lagoons and to some degree seabed types in the littoral zone. For sublittoral ecosystem types there is no existing mapping that gives exact data for either distribution or total area. However, for the major types Euphotic and Aphotic marine rock and Euphotic and Aphotic marine sediment (M1, M2, M4, M5) a rough estimate has been made based on the Norwegian Mapping Authority's bathymetric data for Svalbard and an expert opinion of the ratio between marine rock and sediment substrates. For areas within the territorial border (12 nautical miles outside the baseline) around Svalbard, Bjørnøya, Hopen, Kong Karls Land and Kvitøya, and with a selected dividing line of 40 m between shallow and deep ecosystem types, (roughly the lower limit of the euphotic zone), it is estimated that 20 % of the areas are shallow and 80 % are deep, based on the bathymetric data. The ratio of marine rock to sediment substrates is set at 60/40 % for shallow areas and 40/60 % for deep areas according to an expert opinion. For Norwegian coastal areas the ratio of marine rock to sediment substrate is modelled on water depth and the angle of the bottom substrate (erosion bottom versus accumulation bottom), but the basemap data for large parts of Svalbard, especially on the east side, is unsuitable for the application of this method. It is presumed here that the same ratio between seabed types can be used for all ocean areas around Svalbard.
For most of the more widely distributed ecosystem types there is no basis on which to estimate the total area. In practice therefore only the distribution area is estimated for a large number of the assessment entities, using convex polygons around known and presumed occurrences. For more rare occurrences, where the number of 10 x 10 km grid cells is important for establishing assessment entities, there is also significant uncertainty in many cases, not least for ecosystem types that do not perhaps exist. In such cases an expert-derived assessment is used.
At the major type level Polar sea ice I2 is assessed as Critically Endangered CR. All other major types are assessed as being of Least Concern LC. For the major types Euphotic marine rock M1, Littoral rock M3, Euphotic marine sediment M4 and Aphotic marine sediment M5 the assessment of Least Concern LC is dubious due to future developments that can exceed the threshold values for Near Threatened NT or a threat category. It is changes in climate, invasion of alien species, bottom trawling, and ocean acidification that can impact the ecosystem types at the major type level in particular.
Polar sea-ice with ice fauna I2 is assessed as Critically Endangered CR due to a considerable decline in multi-year ice in the Arctic. This is determined on the basis of criterion A (reduction in geographic distribution) with the highest category obtained under subcriterion A2 (future) due to a projected reduction of more than 80 % of the present-day total area over the next 50 years. At the same time the ice is getting thinner and ice-free periods in summer are becoming longer which also leads to a qualitative change with reduced fauna (criterion C) (Arndt et al 2009). For this assessment the distribution of polar sea-ice in the 1970s and the amount which lay within the territorial border of Svalbard was used as a starting point (Den Norske Los 1988, Lønne 1992). The distribution of polar sea-ice has decreased by about 30 % in 30 years (Meier et al. 2014). The reduction is greatest in the outer areas and with a continued decline the loss in the Svalbard area, in terms of a percentage, will increase in the future. The current total area is roughly estimated to be 14 000 km2 within the territorial border. There are large variations in the area covered by ice both throughout the year and between years. In this case it was decided to estimate the ice-covered area as a maximum distribution in seven or more months per year.
At the minor type level Arctic fjord waterbody is assessed as Endangered EN, while Ice-scoured boulders, Ice-scoured littoral rock and Brackish sand and gravel substrate are assessed as Vulnerable VU. Arctic fjord waterbody is threatened by climate-driven temperature increases due to reduced local ice formation in the fjords and subsequent decreased renewal of bottom water (Weslawski et al. 2010). Over time the decreased water renewal (reduced bottom water formation) will lead to poorer oxygen conditions, perhaps also a temperature increase with loss of species as a consequence (criteria B and C). Ice-scoured boulders and Ice-scoured littoral rock are in decline due to a reduced distribution of polar sea-ice and a decrease in sea-ice formation in the fjords. Polar sea-ice affects the areas at Nordaustlandet and east of Spitsbergen, and is estimated to comprise about a third of the ice-scoured areas. In fjords and coastal areas the formation of annual ice is also in decline, while calving from glaciers will probably continue for quite some time. It is therefore estimated that areas where ice-scour is in decline total more than 50 % of the ice-scoured area. The decline is assessed as somewhat less than for polar sea-ice (around 1 % per year) and is set at 30 % over a 50 year period (criteria A and C). Brackish sand and gravel substrate will be exposed to increased erosion with reduced sea-ice formation in the winter season. There is significant uncertainty concerning both the extent and degree of severity but it is expected that both a reduction in area and changes in the composition of organisms can occur. The assessment entity is categorised as Vulnerable VU based on criterion B2 that the number of occurrences in 10 x 10 km grid cells is limited.
Four assessment entities are categorised as Data Deficient DD due to insufficient knowledge. This applies to Sheltered brackish littoral rock, Shallow shell sand substrate, Maerl beds, and Estuarine inlet and lagoon. Sheltered brackish littoral rock and Shallow shell sand substrate are assigned to DD because their existence is uncertain. If they should exist, both would be threatened by factors that are expected to impact all occurrences; altered freshwater runoff and ocean acidification. Maerl beds will be threatened by ocean acidification which is presumed to be severe in the Far North. It is uncertain how Maerl beds have evolved in the past 50 years and neither is it possible to predict the degree of degradation that can be expected in a future 50 year period. Maerl beds can also be threatened by bottom trawling for scallops. The category DD is selected because the uncertainty is too great to determine a threat category. For Estuarine inlet and lagoon the knowledge about the organism community is extremely poor. The lagoons are affected by many processes that are completely or partially dependent on climate but it is very uncertain what this can lead to, both in terms of the geodynamic processes that form the lagoons and the hydrological conditions that shape the physical environment (Haug and Myhre 2016). A shorter ice season and varying glacier dynamics can impact lagoons both positively and negatively. The category DD is selected because both the minor types in lagoons are unknown and the consequences of climate change are unknown.
Key impact factors
Climate-driven temperature increase is the most important factor that influences Svalbard. In reality, all marine ecosystems on Svalbard can be more or less influenced by climate change. In shallow waters reduced ice cover and increased precipitation in the form of rain will lead to less ice-scour, yet simultaneously increase erosion due to longer ice-free periods, increased particle sedimentation from mud discharged in freshwater runoff and altered water exchange dynamics in fjords (Weslawski et al. 2011, Quillfeldt and Øseth 2016). Communities of algae and fauna associated with ice (ice algae in fjord ice, ice fauna in polar sea ice) will experience a severe decline. At the same time, increased sea temperatures provide better conditions for boreal and low Arctic species which are expanding their distributions ('borealisation' of organism communities). Species that are currently found on the Norwegian coast will be able to become established on Svalbard, as is already the case for blue mussel Mytilis edulis. Biotic interactions in communities can also change, where a possible scenario on marine rock substrates is increased grazing of sea urchins in kelp forests if 'alien species' of sea urchins invade the coastal areas of Svalbard.
In deeper waters the effects of climate change will be less pronounced, but increased particle sedimentation and increased temperatures may impact the communities. New northern distribution limits for motile species such as Atlantic cod Gadus morhua and other types of fish are reported on a regular basis (Quillfeldt and Øseth 2016) In the fjords, the formation of sea-ice can lead to a decrease in local bottom water formation, threatening the presence of high Artic species in Arctic fjord waterbodies.
A future threat is the introduction of alien species. The two most likely species for the current situation are snow crab Chionoecetes opilio which is established in extensive areas north and east in the Barents Sea and red king crab Paralithodes camtschaticus which is established in the coastal areas of Finnmark and northern Troms. The snow crab is expected to establish a population on Svalbard within a few years, while the future of the red king crab is more uncertain. Both species are so-called 'ecosystem engineers' that influence communities of natural organisms to a considerable degree. Climate change leads moreover to more favourable conditions for the establishment of alien species in shallow waters. This applies first and foremost to alien species which are currently spreading in northern Europe, but even local species from the Norwegian coast, with limited abilities to self-disperse, will be alien on Svalbard if they are transported either intentionally or unintentionally (see Alien Species list).
Another future risk factor with widespread impact is ocean acidification. Ocean acidification is expected to have more pronounced effects in Arctic areas than in boreal and southern areas (Brodie et al. 2014, AMAP 2018). Ocean acidification will threaten all calcareous organisms such as maerl; molluscs, crustaceans, bryozoans, and echinoderms. The acidification threatens maerl beds but can also lead to considerable changes on rock substrates, where flat maerl (smooth) and crustose maerl (calcareous crusts) form a hardened layer on stone and bedrock.
Pollution, noise and rubbish associated with human activity will mostly have local effects in the vicinity of human settlements. In general physical encroachments will also be local, but possible dredging of sea lanes and removal of sills will influence the water exchange in affected fjords (Ravolainen et al. 2018). Oil spillage from shipping traffic or shipwrecks can threaten extensive areas in the littoral zone but the impact will generally be of limited duration.
Fishing with bottom trawl gear for resources such as shrimp and cod, as well as other demersal fish and Iceland scallop Chlamys islandica can impact areas with sediment substrates to a considerable degree. Currently, the effects of bottom trawling on Svalbard (Isfjorden and northeast in Hinlopen) appear to be slight (Øseth et al. 2016) but this can change in the future if shrimp fishing increases and other commercial demersal fish species migrate further north with continued rising temperatures. This activity can be expected to grow with longer ice-free periods and increased stocks of commercial species.
Jan Mayen island lies 550 km north of Iceland in a fault zone on the Mid-Atlantic Ridge. It is 53 km long, 16 km at the widest point, and has an area of 373 km2 and no fjords. The island primarily consists of alkaline lava and volcaniclastic rocks. The surrounding seabed is predominantly sand of volcanic origin and a mixed bottom substrate with coarse gravel and bedrock. There is no pronounced continental shelf around the island, but in a few places the lava has flowed out from the mountainsides and built up shallow lava plateaus. Otherwise there are depths of 2000 – 3000 m in the immediate vicinity of the island, especially on the northern side. South of the island there are somewhat shallower areas. There is relatively little discharge of freshwater and terrigenous particles from the island into the sea.
Jan Mayen is situated in a boundary area between the Arctic and Atlantic waters and is therefore influenced by both the cold southward flowing East-Greenland Current and the northward flowing Atlantic Ocean current. The Polar Front is usually localised south of the island, something that indicates that there is a predominance of Arctic water masses around the island (Østerhus and Gammelsrød 1999). In the 1970s and 1980s Jan Mayen was surrounded by pack ice in the period January/February to April, but the reduced ice sheet in the Arctic has in recent years has also influenced and reduced the amount of sea-ice around Jan Mayen.
The littoral zones of Jan Mayen consist of volcanic lava which weathers quickly under the influence of frost, precipitation, wave action and ice scour. The algal vegetation along the shoreline is therefore sparse and exists only in protected inlets. Ice scour and strong wave action, which ensures that cobbles and gravel are in constant motion, limits the development of rich algae communities in the depth range from 0 to approximately 6 metres deep.
Nevertheless, on bedrock from approximately 10 m and deeper there can be well-developed kelp forest dominated by the brown algae Alaria pylaii. The lower limit for sessile algae lies at a depth of around 30 metres.
In marine rock substrate areas in the immediate vicinity of the island, a rich fauna has been registered with sponges, cnidarians, molluscs, echinoderms and ascidians (Gulliksen 1974, Gulliksen et al. 1980). The mussel which is most frequently observed, the wrinkled rock-borer Hiatella arctica, can have a density of greater than a thousand individuals per m2. In bottom areas with elements of more fine particulate matter, the amount of polychaetes and crustaceans increases. Commercially important fishing species have at times included Iceland scallop Chlamys islandica and the northern prawn Pandalus borealis. With regard to the ecosystem types in NiN it is to be expected that only a few major types and a limited number of minor types are represented on Jan Mayen. The degree to which the minor types fit into the current NiN system is unknown.
A volcanic eruption occurred on the northern part of Jan Mayen in 1970 and lava flowed out into the ocean and formed a new coastline of almost 4 km. Studies of the colonisation and succession on the 'new' lava areas in the period 1972-1999 (Gulliksen et al. 2004) show that in shallow waters there are greater similarities between the 'old' and 'newly established' areas after a few years, while in deeper waters (> 15 m) it takes at least 30 years for the development of a community that resembles established communities in 'old' areas. In shallow waters the living conditions are determined to a large degree by the harsh physical conditions, that lead to the organism communities being characterised by small and motile organisms. In deeper waters the conditions are more stable and favour sessile slow-growing species that have a long lifespan.
Group of experts
The expert group for Svalbard – marine areas was composed of Hege Gundersen (chair), Trine Bekkby, Eivind Oug and Bjørn Gulliksen. In addition, a number of persons and institutions contributed to the work. Stein Fredriksen provided valuable input.
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