Seabird and marine mammal at-sea distribution in the western Bering Sea and along the eastern Kamtchatka(Kamtsjatka)Peninsula was determined during 114 transect counts,lasting 30 min each,in September 2018.A total of ...Seabird and marine mammal at-sea distribution in the western Bering Sea and along the eastern Kamtchatka(Kamtsjatka)Peninsula was determined during 114 transect counts,lasting 30 min each,in September 2018.A total of 58000 seabirds were tallied,i.e.a mean value of 510 per count.The most abundant species was short-tailed shearwater:43250 individuals representing 74%of the total.Fulmar and kittiwake represented 13%and 8%of the total.Important geographical differences were noted,concerning both the number of seabird species and their abundance.The following species were tallied mainly in the northern zone(North of 60°N):fulmar(light morphs),short-tailed shearwater,Vega(herring)gull and horned puffin.In the southern zone,including Commander(Komandorski)Islands,observed species included fulmar(dark morphs),pelagic cormorant,glaucous-winged gull,red-legged kittiwake and black guillemot.The vast majority of the 100 cetaceans and 40 pinnipeds were tallied in the southern area,mainly porpoises,killer whale and humpback whale,and Largha(spotted)seal.展开更多
This article is part of our long-term study on the quantitative at-sea distribution of the marine "upper trophic levels"—seabirds and marine mammals—in polar ecosystems, aiming at quantifying the factors i...This article is part of our long-term study on the quantitative at-sea distribution of the marine "upper trophic levels"—seabirds and marine mammals—in polar ecosystems, aiming at quantifying the factors influencing their distribution as well as detecting possible spatial and temporal changes, with special attention to hydrography and to global climate changes. During an expedition of icebreaking RV Polarstern in February 2010, along the North–South transect between New Zealand and the Ross Gyre, off the Ross Sea, 3200 seabirds belonging to 22 identified pelagic species were recorded during 338 half-hour transect counts. Four major hotspots were identified. These were in Sub-tropical Water off New Zealand(up to 300 birds per count), and at the main Southern Ocean fronts: the Sub-Antarctic Front(up to 240 per count), the Antarctic Front(up to 150 per count) and the Polar Front(up to 200 per count), representing the vast majority of recorded seabirds. The most numerous species in the three frontal zones were: prions—mainly slender-billed Pachyptila belcheri—and Salvin’s albatross Thalassarche [cauta]salvini. The eight more abundant species represented 2650 birds, i.e. more than 80% of the total. A random forest clustering method identified four groups of seabird species occupying similar oceanographic niches.展开更多
During the ARK-XXIII/3 expedition of icebreaking RV Polarstern in the high Arctic Ocean(partim north of 73°N)from 25 August to 10 October 2008,550 transect counts lasting 30 min were devoted to seabird and marine...During the ARK-XXIII/3 expedition of icebreaking RV Polarstern in the high Arctic Ocean(partim north of 73°N)from 25 August to 10 October 2008,550 transect counts lasting 30 min were devoted to seabird and marine mammal counts from the bridge.In the whole area,the three most numerous species,kittiwake Rissa tridactyla,fulmar Fulmarus glacialis and Brünnich’s guillemot Uria lomvia represented 90%of the total of 12000 individuals registered,followed by ivory gull Pagophila eburnea,black guillemot Cepphus grylle and Ross’s gull Rodostethia rosea.Four geographical zones were recognized on the basis of number of species and density.Both were especially low in the deeper areas(mean depth of 3000 m),both ice-free and heavily ice-covered:0.3 birds per 30 min count belonging to three and four species respectively.The most numerous species was kittiwake with 0.25 per count(50 individuals)in the ice-covered area.Pinniped numbers were very low as well,the most numerous of the four species tallied being 20 harp seals Phoca groenlandica and 10 ringed seal Pusa hispida.Seven polar bears Ursus maritimus were encountered.These observations were basically confirmed during 12 helicopter flights lasting one hour each with very low numbers:50 kittiwakes and 13 harp seals,almost none in the ice-covered deep zone.A comparison between data obtained from ship and from helicopter seems however to reflect the importance of seabird followers including for long distances.The only cetaceans were two adult belugas Delphinapterus leucas tallied from helicopter.展开更多
The at-sea summertime distribution of marine mammals between South Africa and Antarctica was determined along eight transects surveyed between December 2007 and January 2012. During 1930 30-minute transect counts, 139...The at-sea summertime distribution of marine mammals between South Africa and Antarctica was determined along eight transects surveyed between December 2007 and January 2012. During 1930 30-minute transect counts, 1390 marine mammal individuals were attributed to 19 species： eight toothed whales （Odontoceti）, six pinnipeds, and five baleen whales （Mysticeti）. An additional two toothed-whale species were encountered ＇out of effort＇. The four most numerous species accounted for 85% of the total number of individuals encountered： crabeater seal （Lobodon carcinophagus）, humpback whale （Megaptera novaeangliae）, Antarctic Minke whale （Balaenoptera bonaerensis） and fin whale （B. physalus）. The distribution of these species was related to oceanographic features, such as water masses and fronts, pack ice and ice edge： These differences were statistically highly significant. Biodiversity was compared with other polar marine ecosystems.展开更多
文摘Seabird and marine mammal at-sea distribution in the western Bering Sea and along the eastern Kamtchatka(Kamtsjatka)Peninsula was determined during 114 transect counts,lasting 30 min each,in September 2018.A total of 58000 seabirds were tallied,i.e.a mean value of 510 per count.The most abundant species was short-tailed shearwater:43250 individuals representing 74%of the total.Fulmar and kittiwake represented 13%and 8%of the total.Important geographical differences were noted,concerning both the number of seabird species and their abundance.The following species were tallied mainly in the northern zone(North of 60°N):fulmar(light morphs),short-tailed shearwater,Vega(herring)gull and horned puffin.In the southern zone,including Commander(Komandorski)Islands,observed species included fulmar(dark morphs),pelagic cormorant,glaucous-winged gull,red-legged kittiwake and black guillemot.The vast majority of the 100 cetaceans and 40 pinnipeds were tallied in the southern area,mainly porpoises,killer whale and humpback whale,and Largha(spotted)seal.
文摘This article is part of our long-term study on the quantitative at-sea distribution of the marine "upper trophic levels"—seabirds and marine mammals—in polar ecosystems, aiming at quantifying the factors influencing their distribution as well as detecting possible spatial and temporal changes, with special attention to hydrography and to global climate changes. During an expedition of icebreaking RV Polarstern in February 2010, along the North–South transect between New Zealand and the Ross Gyre, off the Ross Sea, 3200 seabirds belonging to 22 identified pelagic species were recorded during 338 half-hour transect counts. Four major hotspots were identified. These were in Sub-tropical Water off New Zealand(up to 300 birds per count), and at the main Southern Ocean fronts: the Sub-Antarctic Front(up to 240 per count), the Antarctic Front(up to 150 per count) and the Polar Front(up to 200 per count), representing the vast majority of recorded seabirds. The most numerous species in the three frontal zones were: prions—mainly slender-billed Pachyptila belcheri—and Salvin’s albatross Thalassarche [cauta]salvini. The eight more abundant species represented 2650 birds, i.e. more than 80% of the total. A random forest clustering method identified four groups of seabird species occupying similar oceanographic niches.
文摘During the ARK-XXIII/3 expedition of icebreaking RV Polarstern in the high Arctic Ocean(partim north of 73°N)from 25 August to 10 October 2008,550 transect counts lasting 30 min were devoted to seabird and marine mammal counts from the bridge.In the whole area,the three most numerous species,kittiwake Rissa tridactyla,fulmar Fulmarus glacialis and Brünnich’s guillemot Uria lomvia represented 90%of the total of 12000 individuals registered,followed by ivory gull Pagophila eburnea,black guillemot Cepphus grylle and Ross’s gull Rodostethia rosea.Four geographical zones were recognized on the basis of number of species and density.Both were especially low in the deeper areas(mean depth of 3000 m),both ice-free and heavily ice-covered:0.3 birds per 30 min count belonging to three and four species respectively.The most numerous species was kittiwake with 0.25 per count(50 individuals)in the ice-covered area.Pinniped numbers were very low as well,the most numerous of the four species tallied being 20 harp seals Phoca groenlandica and 10 ringed seal Pusa hispida.Seven polar bears Ursus maritimus were encountered.These observations were basically confirmed during 12 helicopter flights lasting one hour each with very low numbers:50 kittiwakes and 13 harp seals,almost none in the ice-covered deep zone.A comparison between data obtained from ship and from helicopter seems however to reflect the importance of seabird followers including for long distances.The only cetaceans were two adult belugas Delphinapterus leucas tallied from helicopter.
文摘The at-sea summertime distribution of marine mammals between South Africa and Antarctica was determined along eight transects surveyed between December 2007 and January 2012. During 1930 30-minute transect counts, 1390 marine mammal individuals were attributed to 19 species： eight toothed whales （Odontoceti）, six pinnipeds, and five baleen whales （Mysticeti）. An additional two toothed-whale species were encountered ＇out of effort＇. The four most numerous species accounted for 85% of the total number of individuals encountered： crabeater seal （Lobodon carcinophagus）, humpback whale （Megaptera novaeangliae）, Antarctic Minke whale （Balaenoptera bonaerensis） and fin whale （B. physalus）. The distribution of these species was related to oceanographic features, such as water masses and fronts, pack ice and ice edge： These differences were statistically highly significant. Biodiversity was compared with other polar marine ecosystems.
