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Joiris C.R.,Laboratory for Polar Ecology PolE | Falck E.,University Center in Svalbard | D'Hert D.,Laboratory for Polar Ecology PolE | Jungblut S.,Laboratory for Polar Ecology PolE | And 3 more authors.
Polar Biology | Year: 2014

The distribution at sea of upper trophic levels—seabirds and marine mammals—is depending on their food availability: high concentrations reflect high prey abundance and thus high biological production. Polar marine ecosystems are characterized by low biodiversity and high biological patchiness. The distribution of predators, as a consequence, shows a similar patchiness. During two expeditions of icebreaking RV Polarstern in June–July 2011, biodiversity in the arctic marine zone north of 70°N was very low, with low numbers of species: 20 seabirds, eight cetaceans, five pinnipeds and polar bear. Moreover, a few species accounted for the majority in numbers: four bird species for 95 % of the total of 23,000 seabirds recorded during 700 transect counts: fulmar Fulmarus glacialis, kittiwake Rissa tridactyla, Brünnich’s guillemot Uria lomvia and little auk Alle alle. Among the marine mammals, 250 fin whales Balaenoptera physalus accounted for 80 % of the identified large cetaceans, 270 white-beaked dolphin Lagenorhynchus albirostris for 100 % of the small cetaceans and 180 harp seals Pagophilus groenlandica for 80 % of the identified pinnipeds. Their quantitative distribution was depending on water masses and oceanic fronts, large cetaceans—mainly fin whales—showing an important aggregation on the shelf slope off western Spitsbergen, as well as little auks and Brünnich’s guillemots. So that this zone, shelf slope and front of mixed Arctic/Atlantic Waters, showed unusually high seabird and cetacean concentrations. Seasonal factors possibly influencing their distribution are addressed. © 2014, Springer-Verlag Berlin Heidelberg.

PubMed | Laboratory for Polar Ecology PolE, University of Bremen and Royal Belgian Institute Of Natural Sciences
Type: | Journal: Scientifica | Year: 2016

The at-sea distribution of top predators, seabirds and marine mammals, was determined in the high Arctic pack ice on board the icebreaker RV

Bergmann M.,Alfred Wegener Institute for Polar and Marine Research | Sandhop N.,Alfred Wegener Institute for Polar and Marine Research | Schewe I.,Alfred Wegener Institute for Polar and Marine Research | D'Hert D.,Laboratory for Polar Ecology PolE
Polar Biology | Year: 2015

Although recent reports indicate that anthropogenic waste has made it to the remotest parts of our oceans, there is still only limited information about its spread, especially in polar seas. Here, we present litter densities recorded during ship- and helicopter-based observer surveys in the Barents Sea and Fram Strait (Arctic). Thirty-one items were recorded in total, 23 from helicopter and eight from research vessel transects. Litter quantities ranged between 0 and 0.216 items km−1 with a mean of 0.001 (±SEM 0.005) items km−1. All of the floating objects observed were plastic items. Litter densities were slightly higher in the Fram Strait (0.006 items km−1) compared with the Barents Sea (0.004 items km−1). More litter was recorded during helicopter-based surveys than during ship-based surveys (0.006 and 0.004 items km−1, respectively). When comparing with the few available data with the same unit (items km−1 transect), the densities found herein are slightly higher than those from Antarctica but substantially lower than those from temperate waters. However, since anthropogenic activities in the Fram Strait are expanding because of sea ice shrinkage, and since currents from the North Atlantic carry a continuous supply of litter to the north, this problem is likely to worsen in years to come unless serious mitigating actions are taken to reduce the amounts of litter entering the oceans. © 2015 The Author(s)

Joiris C.R.,Laboratory for Polar Ecology PolE | Falck E.,Geophysical Institute and Bjerknes Center for Climate Research
Polar Biology | Year: 2011

Among the most numerous seabird and pinniped species of the Fram Strait and the Greenland Sea, little auks Alle alle and harp seals Pagophila (Phoca) groenlandica are very abundant in the mixed Polar/Arctic Waters at the front between the two water masses. This must reflect the presence of very high concentrations of their food, Arctic zooplankton and nekton, massively attracting their predators. Such a high biological production seems to be depending on new primary production based on upwelling and high nutrient concentration. This usually takes place at the ice edge (e. g. July 2005), but hydrological conditions such as eddies can modify its position, east of the front in open water as caused by a subsurface eddy (August 2005), or in ice-covered areas if westerly winds push the pack ice to the east, eventually covering an eddy and causing very high concentrations of little auks and harp seals (July 2008). On the other hand, a dramatic decrease of pack ice coverage can move this water mass farther north and west, making it inaccessible to little auks during their breeding season, and apparently causing breeding failure in Jan Mayen in July 2005. In future years, if a much stronger diminution in sea ice coverage will take place, similar to the retreat in 2005 and 2007, the failure might affect the whole Spitsbergen population, as well as other seabird species feeding mainly at the ice edge. © 2010 Springer-Verlag.

Nachtsheim D.A.,Laboratory for Polar Ecology PolE | Joiris C.R.,Laboratory for Polar Ecology PolE | Joiris C.R.,Royal Belgian Institute Of Natural Sciences | D'Hert D.,Laboratory for Polar Ecology PolE
Polar Biology | Year: 2015

The ivory gull Pagophila eburnea is an Arctic seabird species whose distribution is tightly coupled to the availability of sea ice. During the last decades, strong declines have been reported for breeding colonies in Canada and Greenland, which are usually located on nunataks or remote coastal islands. Here, we report the observation of a colony of ivory gulls breeding on a gravel-covered iceberg 70 km off Northeast Greenland in August 2014. It concerned approximately 60 adults, including two ringed individuals, and many chicks. This represents an unusual breeding site for the species, to be compared with a few cases of colonies on gravel-covered sea ice. Breeding on an offshore iceberg may be advantageous since it provides ultimate protection from predators. Furthermore, the proximity to the productive North East Water polynya may have been attractive to these gulls. As a consequence of this and previous observations, colony surveys should not solely focus on inland and coastal breeding habitats, but should be extended towards the ocean. © 2015 Springer-Verlag Berlin Heidelberg

Joiris C.R.,Laboratory for Polar Ecology PolE | Joiris C.R.,Royal Belgian Institute Of Natural Sciences
Polar Biology | Year: 2016

Our long-term study on top predator (seabirds and marine mammals) distribution in polar marine ecosystems aims at detecting possible temporal and spatial population changes, especially in the context of global changes in temperature and ice cover. Quantitative data on the seabird distribution were collected in the northern Greenland Sea and Fram Strait onboard the icebreaker RV Polarstern between 1988 and 2014, applying 30-min transect counts from the bridge, without width limitation (n = 7320). A drastic decrease in numbers by a factor of seven was detected for the ivory gull Pagophila eburnea from 2007 on. These data confirm the decrease of ivory gull previously detected in North Canada and North Greenland, leading to the conclusion that the species is “endangered” or “near threatened”. These changes are discussed in relation to the decreasing Arctic pack ice coverage leading to the opening of the Northwest and Northeast Passages in 2007, at the time the year with the lowest ice coverage ever recorded. On the other hand, the decrease was even stronger for Ross’s gull Rhodostethia rosea after 1993, apparently reflecting changes in migratory habits. The third high Arctic gull, Sabine’s gull Xema sabini, was only tallied in very low numbers, without any clear temporal evolution in numbers. © 2016 Springer-Verlag Berlin Heidelberg

Joiris C.R.,Laboratory for Polar Ecology PolE | Humphries G.R.W.,University of Otago | De Broyer A.,Royal Belgian Institute Of Natural Sciences
Polar Biology | Year: 2013

The first aim of our long-term study on the at-sea distribution of the upper trophic levels-seabirds and marine mammals-in polar marine ecosystems is to identify the main factors affecting their distribution: water masses and pack ice, fronts and ice edge as defined on the basis of water temperature, salinity and ice overage. In this study, seabird at-sea distribution was determined in the south-eastern Atlantic Ocean in summer along four return transects between Cape Town, South Africa, and Queen Maud Land, Antarctica: two on board icebreaking MS Ivan Papanin and two on board icebreaking RV Polarstern between December 2007 and January 2012. During a total of 1,930 half-an-hour transect counts devoted to seabird recording, 69,000 individuals were encountered, belonging to 57 species (mean: 36 individuals per count, all species and expeditions pooled). In comparison, the adjacent Weddell Sea shows a lower seabird biodiversity (30 species and 150 individuals per count) than in the area covered by this study. European Arctic seas reflect an intermediate biodiversity, with 30 species and 60 individuals per count; the major difference is observed in closed pack ice, almost empty in the Arctic but showing a very high biomass in the Antarctic. On the other hand, following the same route in different years allowed to compare results: density and abundance were found to be homogenous and reproducible between years for some species, while very important patchiness was detected for others, causing large heterogeneities and differences between expeditions. © 2013 Springer-Verlag Berlin Heidelberg.

Joiris C.R.,Laboratory for Polar Ecology PolE | Joiris C.R.,Royal Belgian Institute Of Natural Sciences | D'Hert D.,Laboratory for Polar Ecology PolE
Polar Biology | Year: 2015

During the PS75 expedition of ice-breaking RV Polarstern in the Amundsen Sea, in February–March 2010, we studied the at-sea quantitative distribution of the “upper trophic levels,” seabirds and marine mammals. In the Amundsen Sea Embayment, 14,200 pinnipeds belonging to four species were recorded (2100 during 670 half-hour transect counts from the bridge and 12,100 during 50 h of helicopter flight). Crabeater seal Lobodoncarcinophaga represented more than 97 % of the total. Two types of major aggregations of crabeaters were noted: on the one hand, very large groups hauled out on the pack ice, composed mainly of adults/bachelors and very few calves. On the other hand, swimming pods of calves were accompanied by one or two leading adults around icebergs. Our interpretation is that, after the beginning of the reproduction period with trios (cow, calf and future father) scattered on pack ice, such pods can be considered the last step of the breeding cycle. © 2015 Springer-Verlag Berlin Heidelberg

Joiris C.R.,Laboratory for Polar Ecology PolE | Dochy O.,Laboratory for Polar Ecology PolE
Polar Biology | Year: 2013

The main aim of our long-term study on the at-sea distribution of the upper trophic levels in polar marine ecosystems is to deepen the understanding of the basic mechanisms affecting their distribution, i.e. hydrological factors such as water masses and fronts, pack ice and ice edge, eddies. A second goal consists in detecting spatial and temporal changes, with special attention to global climate changes, as well as possible consequences of (krill) fisheries. Seabirds and marine mammals were recorded during an autumn expedition of icebreaking RV Polarstern between Punta Arenas and the South Shetland Islands, Antarctica in March/ April 2012. During a total of 333 half-an-hour transect counts without width limitation, 113,500 seabirds were encountered, belonging to 40 species. The vast majority were southern fulmars and grey-headed albatross around the South Shetland Islands, with 76,800 and 7,000 individuals, respectively. Fin whale was by far the most abundant cetacean with 300 identified individuals in the same area, of which 100 in one count. These exceptional concentrations of fin whale seem to reflect an autumn pre-migration feeding aggregation. For most species, the majority was concentrated in very few counts, reflecting a very high patchiness and, as upper trophic levels, an important prey availability-mainly krill, nekton and small fish. Low biodiversity was reflected by both the low number of species and the fact that a few species represent the vast majority in numbers. It is suggested that the area deserves future biological studies, especially in autumn, and a special protection management. © 2013 Springer-Verlag Berlin Heidelberg.

Joiris C.R.,Laboratory for Polar Ecology PolE
Polar Biology | Year: 2011

In the frame of our long-term study of the distribution of seabirds and marine mammals in polar seas, observers from this team participated in the European Arctic expeditions of icebreaking RV Polarstern during summer 2008. The main aims were to obtain more information on the mechanisms underlying the at-sea distribution of the 'higher trophic levels' and to detect possible temporal and spatial changes in numbers, especially in function of climatic changes and decreasing ice coverage in the Arctic. In total, 1,175 half-an-hour transect counts were devoted to seabird and marine mammal distribution in the Greenland and Norwegian Seas, from 14 June to 15 August, 2008. A major feeding ground for cetaceans and seabirds was detected in the south-western Greenland Sea and the Denmark Strait in the Polar Front between Polar and Arctic Water masses. For the main cetacean and seabird species, almost all individuals recorded during the whole expedition were encountered in this limited zone of 33 counts: 135 humpback whales Megaptera novaeangliae and 1,940 common guillemots Uria aalge. Moreover, 4,400 fulmars Fulmarus glacialis light morph were observed in this zone, i. e. close to half of the total. All were actively feeding, making this zone the major feeding ground for the higher trophic levels in the European Arctic Seas and so confirming the great importance of fronts (upwellings) for the biological productivity of the oceans. Such data are essential for a successful conservation and management of the Denmark Strait and adjacent areas. © 2011 Springer-Verlag.

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