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Background: Sooty (Puffinus griseus) and short-tailed (P. tenuirostris) shearwaters are abundant seabirds that range widely across global oceans. Understanding the foraging ecology of these species in the Southern Ocean is important for monitoring and ecosystem conservation and management. Methodology/Principal Findings: Tracking data from sooty and short-tailed shearwaters from three regions of New Zealand and Australia were combined with at-sea observations of shearwaters in the Southern Ocean, physical oceanography, nearsurface copepod distributions, pelagic trawl data, and synoptic near-surface winds. Shearwaters from all three regions foraged in the Polar Front zone, and showed particular overlap in the region around 140°E. Short-tailed shearwaters from South Australia also foraged in Antarctic waters south of the Polar Front. The spatial distribution of shearwater foraging effort in the Polar Front zone was matched by patterns in large-scale upwelling, primary production, and abundances of copepods and myctophid fish. Oceanic winds were found to be broad determinants of foraging distribution, and of the flight paths taken by the birds on long foraging trips to Antarctic waters. Conclusions/Significance: The shearwaters displayed foraging site fidelity and overlap of foraging habitat between species and populations that may enhance their utility as indicators of Southern Ocean ecosystems. The results highlight the importance of upwellings due to interactions of the Antarctic Circumpolar Current with large-scale bottom topography, and the corresponding localised increases in the productivity of the Polar Front ecosystem. [ABSTRACT FROM AUTHOR]

Abstract: Seabird surveys in January – March 2006 of a poorly known area of the Southern Ocean adjacent to the East Antarctic coast identified six seabird communities, several of which were comparable to seabird communities identified both in adjacent sectors of the Antarctic, and elsewhere in the Southern Ocean. These results support previous proposals that the Southern Ocean seabird community is characterised by an ice-associated assemblage and an open-water assemblage, with the species composition of the assemblages reflecting local (Antarctic-resident) breeding species, and the migratory routes and feeding areas of distant-breeding taxa, respectively. Physical environmental covariates such as sea-ice cover, distance to continental shelf and time of year influenced the distribution and abundance of seabirds observed, but the roles of these factors in the observed spatial and temporal patterns in seabird assemblages was confounded by the duration of the survey. Occurrence of a number of seabird taxa exhibited significant correlations with krill densities at one or two spatial scales, but only three taxa (Arctic tern, snow petrel and dark shearwaters, i.e. sooty and short-tailed shearwaters) showed significant correlations at a range of spatial scales. Dark shearwater abundances showed correlations with krill densities across the range of spatial scales examined. [Copyright &y& Elsevier]

The article presents three ecological scenarios which demonstrate the influence of cetaceans on the structure and dynamics of the food web in the Southern Ocean. It notes the impact of killer whales on the K-selected prey populations and the fur seal populations' extreme sensitivity to predation by leopard seals. It indicates that cetaceans' population fluctuations appear to play an important role in the changes seen in the Antarctic marine ecosystem in the past and in the present.

Investigations in recent years of the ecological structure and processes of the Southern Ocean have almost exclusively taken a bottom-up, forcing-by-physical-processes approach relating various species' population trends to climate change. Just 20 years ago, however, researchers focused on a broader set of hypotheses, in part formed around a paradigm positing interspecific interactions as central to structuring the ecosystem (forcing by biotic processes, top-down), and particularly on a "krill surplus" caused by the removal from the system of more than a million baleen whales. Since then, this latter idea has disappeared from favour with little debate. Moreover, it recently has been shown that concurrent with whaling there was a massive depletion of finfish in the Southern Ocean, a finding also ignored in deference to climate related explanations of ecosystem change. We present two examples from the literature, one involving gelatinous organisms and the other involving penguins, in which climate has been used to explain species' population trends but which could better be explained by including species interactions in the modelling. We conclude by questioning the almost complete shift in paradigms that has occurred and discuss whether it is leading Southern Ocean marine ecological science in an instructive direction. [ABSTRACT FROM AUTHOR]

Conservation of the high seas marine environment poses a significant challenge to policy-makers and managers. Marine conservation efforts are often hindered by the lack of data and the difficulties in addressing multiple, and typically conflicting uses. The majority of extant Marine Protected Areas (MPAs) are in coastal or tropical regions within national jurisdiction. Conservation of high seas MPAs has emerged on the international agenda as a critical issue requiring the application of novel approaches, international cooperation and political will. Knowledge and understanding of the marine environment and data on marine biodiversity are all typically limited for the high seas, and the use of surrogates to assist in the identification of areas of high conservation value is one possible mechanism to address and potentially overcome these limitations. Drawing upon a database spanning more than 20 years and containing approximately 140 000 records of seabird sightings at sea, this study assesses the potential use of seabirds as surrogates for marine biodiversity in the Indian sector of the Southern Ocean. At-sea ranges, species diversity and the distributions of endangered species may be appropriate selectors or filters to identify areas with high conservation values. Integrating policy with science provides an appropriate mechanism to identify and prioritise MPAs in the Southern Ocean. [ABSTRACT FROM AUTHOR]

The relationships between behaviour and synoptic-scale weather patterns and wind speeds for wandering (Diomedea exulans), black-browed (D. melanophrys) and light-mantled sooty (Phoebetria palpebrata) albatrosses were examined using observations collected from ships in the Southern Ocean south of Tasmania, Australia. Wandering albatrosses were found in high-pressure systems in significantly higher numbers than expected than in low-pressure systems. Wandering albatrosses were also found more frequently at lower latitudes than were black-browed and light-mantled sooty albatrosses. Light-mantled sooty and black-browed albatrosses showed no significant association with high- or low-pressure systems, suggesting that they can use either pressure system for travel. High-pressure systems may act as "traps" for wandering albatrosses, due to the lower wind speeds generally associated with these systems. [ABSTRACT FROM AUTHOR]

Abstract: Waters off the western Antarctic Peninsula (i.e., the eastern Bellingshausen Sea) are unusually complex owing to the convergence of several major fronts. Determining the relative influence of fronts on occurrence patterns of top-trophic species in that area, therefore, has been challenging. In one of the few ocean-wide seabird data syntheses, in this case for the Southern Ocean, we analyzed ample, previously collected cruise data, Antarctic-wide, to determine seabird species assemblages and quantitative relationships to fronts as a way to provide context to the long-term Palmer LTER and the winter Southern Ocean GLOBEC studies in the eastern Bellingshausen Sea. Fronts investigated during both winter (April–September) and summer (October–March) were the southern boundary of the Antarctic Circumpolar Current (ACC), which separates the High Antarctic from the Low Antarctic water mass, and within which are embedded the marginal ice zone and Antarctic Shelf Break Front; and the Antarctic Polar Front, which separates the Low Antarctic and the Subantarctic water masses. We used clustering to determine species'' groupings with water masses, and generalized additive models to relate species'' densities, biomass and diversity to distance to respective fronts. Antarctic-wide, in both periods, highest seabird densities and lowest species diversity were found in the High Antarctic water mass. In the eastern Bellingshausen, seabird density in the High Antarctic water mass was lower (as low as half that of winter) than found in other Antarctic regions. During winter, Antarctic-wide, two significant species groups were evident: one dominated by Adélie penguins (Pygoscelis adeliae) (High Antarctic water mass) and the other by petrels and prions (no differentiation among water masses); in eastern Bellingshausen waters during winter, the one significant species group was composed of species from both Antarctic-wide groups. In summer, Antarctic-wide, a High Antarctic group dominated by Adélie penguins, a Low Antarctic group dominated by petrels, and a Subantarctic group dominated by albatross were evident. In eastern Bellingshausen waters during summer, groups were inconsistent. With regard to frontal features, Antarctic-wide in winter, distance to the ice edge was an important explanatory factor for nine of 14 species, distance to the Antarctic Polar Front for six species and distance to the Shelf Break Front for six species; however, these Antarctic-wide models could not successfully predict spatial relationships of winter seabird density (individual species or total) and biomass in the eastern Bellingshausen. Antarctic-wide in summer, distance to land/Antarctic continent was important for 10 of 18 species, not a surprising result for these summer-time Antarctic breeders, as colonies are associated with ice-free areas of coastal land. Distance to the Shelf Break Front was important for 8 and distance to the southern boundary of the ACC was important for 7 species. These summer models were more successful in predicting eastern Bellingshausen species density and species diversity but failed to predict total seabird density or biomass. Antarctic seabirds appear to respond to fronts in a way similar to that observed along the well-studied upwelling front of the California Current. To understand fully the seabird patterns found in this synthesis, multi-disciplinary at-sea investigations, including a quantified prey field, are needed. [Copyright &y& Elsevier]