The nutrient-rich icefjord - animals and plants

^{Freshwater, from melting of ice at the bottom of icebergs, will flow up along the side of the iceberg because freshwater is lighter than the surrounding salt water.}

The rich marine flora and fauna of Kangia are closely connected with the ice and the stranded icebergs at the mouth of the fjord. As noted above this is due to the strong turbulence and up-welling of nutrients into the upper water layers. When the ice at the bottom of icebergs melts, the melt water rises along the sides of the icebergs because fresh water is lighter than the surrounding salt water. The upward currents create turbulence in the whole column of water, and this causes up-welling of relatively warm and nutritious water. The icebergs thus contribute to nourishment of the upper water layers and the flourishing plankton life at the surface. The high primary plankton production culminates in the summer, and provides the food foundation for the fjord’s rich animal life.

^{Tegningen viser, hvordan store isfjelde tilfører overfladevandet næring. Ferskvand, som smelter i bunden af isfjeldene, er lettere end det omgivende saltvand. Derfor bevæger ferskvandet sig opad mod overfladen. Strømmene omkring isfjeldene skaber turbulens i hele vandsøjlen, hvilket bringer varmt og næringsrigt vand med op fra dybere lag til gavn for produktionen af planteplankton.}

Tidal effects, 2 to 3 metres between ebb and flood, ensure an effective exchange of water between the icefjord and Disko Bugt. This also promotes the production of plant plankton, zooplankton and crustaceans, which attract fish, seals and whales.

The tightly packed icebergs and the sea ice have hindered studies of the flora and fauna in Kangia itself. Detailed studies of life have therefore focussed on the more easily accessible areas at the mouth of the fjord.

Knowledge about the occurrence and distribution of marine plankton in the icefjord is sparse. Studies in Disko Bugt show that the concentration of both nutrients and plant plankton rise markedly in the direction of Ilulissat and the mouth of Kangia, and this is without doubt due to the high primary production in the icefjord and the addition of nutrients from subglacial erosion. The Disko Bugt area has a very high primary production of nutrients compared with most of West Greenland. Only a very few other fjord mouths exhibit comparable high concentrations of nutrients and plankton.

Marine plankton have been investigated along a transect from Ilulissat to Qeqertarsuaq on Disko. The local processes in Ilulissat Isfjord, with melting and run-off from the glacier, can be seen to create a transport of freshened surface water that forms a vital foundation for the rich occurrences of plant plankton and zooplankton in the upper water masses.

^{Copepods are planktonic crustaceans that play a central role in the food chain of the oceans in arctic regions. They are being eaten by for example fish and birds, and are also important in the diet of the Greenland whale. (Photos: Torkel Gissel Nielsen)}

Greenland halibut is the dominant fish species in the Kangia eco-system. Unlike other flatfish species, halibut live both at the bottom and at higher levels of the free water masses. Halibut flourish in cold water, in part because they are ousted by cod in warmer water. Halibut live in the whole of the fjord system, but are known for their seasonal migrations. Thus in summer halibut are mostly found in the inner parts of the fjord, while their occurrence is more evenly distributed in winter.

At the mouth of Kangia halibut are subjected to one of the most concentrated types of fishing in the world, in terms of the quantity caught in a small area. Fishing is difficult in the icefjord itself, and the fjord is thus an important ‘protected’ refuge area for halibut, where they can thrive in peace and become up to 25 years old.

^{Greenland halibut is widespread in Kangia and on Isfjeldsbanken at the mouth of the fjord. The halibut can be up to 25 years old, and in rare cases become up to 120 cm long and weigh 45 kg. (Illustration: © Scandinavian Fishing Year Book).}

The low bottom temperatures of the icefjord (< 2°C), suggest that halibut does not spawn in the fjord itself. The stock is therefore probably not self-recruiting, but is thought to derive from a spawning population in Davis Strait. Adult halibut in the icefjord seldom return to their spawning stock, but are believed to remain in the fjord for the whole of their adult lives. Thus, no matter how heavily the stock is fished, fishing has no impact on the spawning stock in the Davis Strait and thus on the recruitment to the icefjord. However, fishing does impact on the composition of the stock in the icefjord, and the average age of the halibut caught has fallen considerably in recent decades in line with the increase in intensity of fishing activity.

Management of fishing off Kangia is thus more a matter of maintaining species diversity than of the sustainability of the halibut resource. The aim of the management is to maintain the annual catch from the stock at a level that will ensure a continued stable catch. At the same time, the authorities put weight on responsible methods of fishing that minimise any damaging effects on the bottom habitat of the fjord and the area off its mouth, through the fishing itself and through the loss of fishing tackle.

Northern shrimps are the favourite prey of halibut. Shrimps are widespread in the whole of Kangia and in the waters off the mouth of the fjord. Shrimps and other crustaceans are important prey for most fish species in West Greenland. The older shrimps seem to live on the bottom during the day, and in the higher free water masses at night.

^{Photo: Jesper Boje}

^{Source: Det kongl. danske videns. selsk.1936, Ad .S. Jensen}

Another important prey species is the small salmonoid fish capelin, which is found locally in large numbers, and gathers in small bays at spawning time. Farther north, capelin is replaced by polar cod, which has become more abundant in Kangia and Disko Bugt in recent years. A number of eelpout species, which live at the bottom of the icefjord, are also important prey for halibut.

New research with electronic marking of halibut shows that halibut forage in deep water as well as close to the surface. The migrations up and down through the icefjord’s c. 1000 m deep water column occur irregularly throughout the day, and are probably connected with the presence of prey. These studies have also shown that the icefjord and the water off its mouth are integrated parts of the foraging territory of the halibut.

Halibut are themselves the prey of the Greenland shark and the ringed seal. The Greenland shark is common in the icefjord, although it has been fished intensively as a secondary catch in long line fishing for halibut. Studies in which Greenland sharks have been marked have shown that the species travels very large distances, and the sharks in the icefjord are believed to form part of the stock common to the coastal waters of the whole of West Greenland

Fin whales and minke whales are often seen in summer along the outer margin of Isfjeldsbanken at the mouth of the fjord. Humpback whales are rare summer visitors, and blue whales and Greenland right whales are rare guests. Beluga and narwhal are found in Disko Bugt in the autumn and winter, and have occasion-ally been seen in Kangia.

^{A humpback whale flicks its tail.}

^{Ringed seals live in the icefjord all the year round. (Photo: Christian Glahder)}

It is said locally that halibut disappear from the fishing catch totally when the beluga arrive. The halibut apparently burrow into the sediment at the bottom of the fjord to avoid the beluga, which prefer to eat halibut. The harp seal is common in open water in summer and the ringed seal lives in the icefjord all year around. The seals feed on fish such as capelin, redfish and polar cod, supplemented by squid and crustaceans. Polar bears, which hunt seals along the coast, are extremely rare visitors to the area.

The bird life at Kangia is generally typ-ical for fjord landscapes in central West Greenland. However, large flocks of northern fulmars and gulls are particularly common around the stranded icebergs at the mouth of the fjord. Bird life on land is sparse and is dominated by snow buntings, Lapland buntings and ravens.

Little has been published about the bird life around Kangia and the following passages are based largely on information from local people and from biologists who have passed through the area in connection with other field activities.

Sea birds:

There are a number of sea bird breeding colonies along the coasts in the Ilulissat area, including colonies of Iceland gull and kittiwake, and a few of cormorants. The most impressive sea birds are the large flocks of northern fulmars, which find their food amongst the grounded icebergs on Isfjeldsbanken. The fulmars come from large breeding colonies on Disko and on the small island Qeqertaq in Disko Fjord, about 100 km west of Ilulissat. The population is thought to number more than 100,000 breeding pairs. Large flocks of Iceland gulls and glaucous gulls forage frequently amongst the stranded icebergs, together with lesser numbers of great black-backed gulls and kittiwakes. The fulmars and the gulls are attracted by the zooplankton in the waters at the mouth of Kangia, as well as discarded fish refuse from the trawlers and boats fishing for halibut.

^{Red-throated diver on its nest.}

^{Moulting ptarmigan.}

Land birds:

The relatively sparse bird life on land includes the widespread Greenland species such as snow bunting, Lapland bunting, redpoll, wheatear and raven. The Greenland white-fronted goose is also found. Geese fitted with small transmitters were traced to the area by satellite in the spring of 1999, and according to local hunters breed on Nunatarsuaq. The breeding area for Greenland white-fronted goose is limited to West Greenland, and is estimated to comprise a total of only 30,000 individuals, which all winter in the British Isles. Other Greenland birds found in the Ilulissat area include peregrine falcon, gyr falcon and ptarmigan, all of which are believed to breed here, at least occasionally. The little arctic redpoll appears as a winter guest from more northerly areas in Greenland. The red-throated diver, the great northern diver, Canada goose, mallard, long-tailed duck, red-breasted merganser, red-necked phalarope and purple sandpiper also probably breed in the area.

^{Location of sea-bird colonies in the Ilulissat area.
Colony number 1 is a great cormorant (Phalacrocorax carbo) and Iceland gull (Larus glaucoides) colony. In 1976 there were 170 pairs of Iceland gulls, while the number of cormorant nests was unknown. Cormorants were noted at colony number 2 in 1995, but breeding was not confirmed. Colony number 3 is a kittiwake (Risa tridactyla) colony, with in 1976 a total of 15 pairs in company with 100 pairs of Iceland gulls. The two cliff colonies, numbers 4 and 5, are probably Iceland gulls. Colony number 6 is probably a breeding colony of Iceland gulls. Colony number 7 on a steep cliff also comprises Iceland gulls, and further colonies of gulls have been reported at sites 8 and 9.}

Visiting birds:

A large number of bird species are found as more or less regular guests in the area, either on migrations in the spring and autumn or as summer guests. These include, for example, brent goose, harlequin duck, eider, pomarine skua, arctic skua, arctic tern and Brünnich’s guillemot.

Available information about mammals on land in the Ilulissat area is limited, but the arctic fox is quite common. The arctic fox is one of the warm-blooded animals that have adapted best to the cold. In winter they can keep warm in temperatures as low as minus 40°C without moving, due to their highly insulating fur. The arctic fox eats anything and everything, and has an amazing ability to adapt. It catches fish in the tidal zone, takes birds, eggs and insects, feeds on carrion and it also eats abundant berries in the autumn.

^{The arctic fox eats anything and everything, and has an amazing ability to adapt.}

The arctic hare is fairly rare in the area and is mainly found in the higher-lying areas near the margin of the Inland Ice. It eats a broad range of plants, and survives the arctic winter by burrowing its way down to plants in areas with little snow cover.

^{Adult arctic hares can weigh up to five kilograms, more than a fully grown fox, which does not usually hunt them. Arctic hares are often seen in flocks in winter.}

Reindeer are found locally in the area south of Kangia. However, they have not been recorded from the areas on the north side of the fjord in modern time. Some place names indicate that they have lived there in the past, and this is supported by finds of reindeer bones from the Dorset and Thule cultures in the midden at Sermermiut. Reindeer are the only mammals that regularly eat lichens. In winter the reindeer reach the lichen by scraping through the snow with their hooves.

^{Reindeer on the run.}

The flora in the Ilulissat area is low arctic and reflects the nutrient-poor, silica-rich rocky ground. About 160 species of flowering plants, three species of club-mosses, two species of horsetails and four species of ferns are known from the area, and the plants colonise new areas as the ice margin retreats. Some species are seen nearly everywhere, while others are only found at a few locations. However, even the most common species have their preferred growing sites in one or several characteristic plant communities.

The dominant plant communities are heath, fell-field, snow-patch, herb slope, willow-scrub, fen, riverbank and seashore vegetation. In addition there are a number of plants that grow in lakes and ponds.

^{Arctic plants are growing in cracks in the bedrock.}

Heath:

As in many other parts of Greenland, the most widespread plant community is heath, dominated by dwarf-shrubs which form a uniform growth over large areas. Dwarf birch, crowberry and arctic blueberry are the typical species, of which the last two give a good yield of berries in the late summer. Arctic bell-heather is common on north-facing slopes. In the most sheltered areas, mountain heath can form dense growth with thousands of red-lilac, bell-shaped flowers. Other common heath plants are the strongly aromatic, stunted bush Labrador-tea and fir club moss, which stretch their curved, green fingers up from the moss. The little white-flowered herb, long-stalked stitchwort, is rarely absent. Grasses such as the arctic meadow grass and Alpine sweet grass often stand out among the stunted bushes. Rock cranberry is also found, but is rare.

The bushes are more widely spaced where the heath is subject to strong drying winds. This gives room for herbs such as the beautiful hairy lousewort, which stands out with its light red inflorescence and the white tomentose Labrador cat’s-paw. Lapland rose-bay, with leathery leaves and large blue-lilac flowers, is found on the more nutritious places, and fits in well with entire-leafed mountain avens, which also grow here with their large, whitish-yellow flowers.

Most ferns avoid dry conditions such as sunny rock crevices, although the fragrant shield-fern does grow at such sites. Brown, withered leaves several years old protect the new dark-green leaves. Three-toothed saxifrage, which is one of the few prickly plants in Greenland, also prefers dry rock cracks.

^{Arctic poppy}

^{White Arctic bell-heather (Cassiope tetragona).}

Fell-field:

Plants are more scattered on the fell-fields. The distance from one green tussock to the next can be long, either because it is too dry or too windy, or because the soil is so coarse-grained that it cannot retain moisture. Nevertheless, flowers can nearly always be found if one looks for them, and there are often many species, because the competition between species is minimal. Snow whitlow-grass and Lapland diapensia are common, both with white flowers, in addition to the yellow-flowered arctic poppy and the butter-yellow snow cinquefoil with white undersides to its leaves. The small, dark head of the northern wood-rush is also frequent on the fell-fields.

Patterned ground and other interesting soil phenomena caused by frost action are common. Polygonal patterns are developed in stony soil, with the coarser grained material along the edges of the polygons and finer material in the centres. During the thaw, the centres of the polygons are soft and sticky because the melt water cannot seep down into the permanently frozen soil. Later in the summer the upper soil dries out. Plants that can survive on this type of ‘living’ soil need special abilities. For example, grained saxifrage forms scores of small leaf buds instead of flowers, which detach from the inflorescence and sprout in the soft soil.

Snow-patch:

Places where the snow remains for most of the summer are called snow-patches. Here the growing season for plants is only four to six weeks long. For the rest of the year the plants are covered by a thick, protective layer of snow. Mosses, lichens and dwarf willow are found in snow-patches. The branches of dwarf willow are often hidden in the soil, with only the leaves and inflorescence protruding above the surface. The male plants have yellow inflorescence, while those of the female plant are red. Moss heather is found in the more heath -like snow-patches. Other characteristic herbs are the annual pigmy buttercup, with small, yellow flowers, dandelion and mountain sorrel. It is possible to make a nourishing fruit soup using mountain sorrel:

"by boiling a large bunch of stems in a pot until tender, straining the juice and adding sugar to taste".

^{Mountain sorrel.}

^Willow.

Herb-slopes:

The most lush plant community in the area is the herb-slope, or ‘urteli’, which carries a vegetation very rich in species on strongly sloping areas. ‘Urte’ means herb in Danish and Norwegian, and ‘Li’ is a ‘slope’ in Norwegian. Herb-slopes develop on the south or south-west facing slopes beneath high, steep mountains, where they receive meltwater throughout the summer and receive the maximum amount of light from the sun; this creates a warm and mild microclimate. At the same time they are fully protected in winter by a thick layer of snow. Thirty different species of flowering plants can grow on such slopes, including species such as Alpine bistort, Unalaska fleabane and Alpine bartsia, with dark-red flowers and bracteoles. Between the higher herbs one can be lucky to find the little thick-leafed whitlow-grass with its light-yellow flowers.

Willow scrub:

Willow scrub around Kangia can grow to considerable heights in the most lush valleys, in some cases up to 1.5 m. In most places the willow scrub is only knee high, but for the plants at the bottom of the scrub this is of little importance as long as they have shade and shelter. Here one can find interrupted club-moss and common horsetail and, in the drier scrub, round-leafed wintergreen with large flowers.

Seashore:

Seashores have their own vegetation, with sandy shores having the characteristic species sea sandwort and lyme-grass. Gravel sedge, sea plantain, Greenland scurvy grass and low stitch-wort are found on coasts with rocks and gravel. On clayey coasts grassy veget- ation develops, that is dominated by creeping saltmarsh-grass, with Pacific silverweed with its yellow flowers brightening the upper part of the shore.

Stony riversides:

Stony riversides are widespread in the area. Here seasonal variations in the water supply result in frequent flooding. In this unstable environment the most conspicuous species is the broad-leafed willow-herb with its pink flowers. This is Greenland’s national flower, and the poetic Greenlandic name ‘niviarsiaq’ translates as ‘young girl’.

Fen:

The richest fens and mires have a thick vegetation of grass-like plants, often dominated by arctic water sedge with its thick straw and upright female spikes, and loose-flowered Alpine sedge which carries beautiful hanging female spikes. Arctic marsh willow, which has branches that creep through the vegetation, is rarely absent; the beautiful red catkins can be up to 10 cm long. The yellow ‘candlesticks’ of flame-tipped lousewort are also common, while the frail Lapland buttercup is rarer.

^{Cottongrass..}

^{Broad-leaved willow plant.}

Lakes and ponds:

Mares-tail is the most common of the proper aquatic plants. The characteristic green ‘Christmas trees’ stand half-covered by water along the banks of many ponds, small lakes and slowly flowing rivers. Northern bur-reed has long ribbon-like leaves that float on the surface of the water and are aligned by the prevailing wind; only the inflorescence is above the water-surface. Completely covered by water is the small pondweed, white water-buttercup and, here and there, a very small green leaf rosette of water awlwort, which only flowers if the pond dries out. Freely floating in the water may be found the quite rare autumnal water-starwort. In many places there is marsh-like vegetation on the banks of lakes and ponds, where one can see plants such as bleaked sedge and arctic cotton-grass. Where water trickles throughout the summer the insect-eating butterwort grows, whose sticky, enzyme-rich leaves hold and decompose small animals. The little mudwort thrives in rock puddles, even if the puddle dries up.

^{Phytogeographical zonation of Greenland.}