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
We investigated the role of hydrological features, such as water masses, fronts, eddies, and sea ice, in affecting the distribution of upper trophic level species in the Scotia Sea region during autumn. On board RV Po...We investigated the role of hydrological features, such as water masses, fronts, eddies, and sea ice, in affecting the distribution of upper trophic level species in the Scotia Sea region during autumn. On board RV Polarstern, we performed 365 30-min strip transects recording seabirds and marine mammals along the North Scotia Ridge and the South Sandwich Trench in March--April 2013. Among the 7 identified cetacean species recorded, the humpback whale Megaptera novaeangliae was the most abundant baleen whale （40 individuals）, and noteworthy were sightings of six southern right whales Eubalaena australis. Pinnipeds （3 species, 1650 individuals） were dominated by Antarctic fur seal Arctocephalus gazella （99%）, and seabirds （36 species, 18900 individuals） by Antarctic prion Pachyptila desolata （-50%）. The distribution of these top predators was highly patchy with the majority of observations concentrated in a few counts. This heterogeneity is likely a result of prey availability, and we discuss how hydrological features may have caused the patchiness.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We investigated the role of hydrological features, such as water masses, fronts, eddies, and sea ice, in affecting the distribution of upper trophic level species in the Scotia Sea region during autumn. On board RV Polarstern, we performed 365 30-min strip transects recording seabirds and marine mammals along the North Scotia Ridge and the South Sandwich Trench in March--April 2013. Among the 7 identified cetacean species recorded, the humpback whale Megaptera novaeangliae was the most abundant baleen whale （40 individuals）, and noteworthy were sightings of six southern right whales Eubalaena australis. Pinnipeds （3 species, 1650 individuals） were dominated by Antarctic fur seal Arctocephalus gazella （99%）, and seabirds （36 species, 18900 individuals） by Antarctic prion Pachyptila desolata （-50%）. The distribution of these top predators was highly patchy with the majority of observations concentrated in a few counts. This heterogeneity is likely a result of prey availability, and we discuss how hydrological features may have caused the patchiness.
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.
