Seabird aggregation around free-drifting icebergs in the northwest Weddell and Scotia Seas

Ruhl, Henry A.; Ellena, Jacob A.; Wilson, Robert; Helly, J.

doi:10.1016/j.dsr2.2010.11.028

Cited by 17 publications

(9 citation statements)

References 52 publications

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“…This strongly suggests that Antarctic petrels use icebergs as platforms to stand on and/or rest during winter, although it was not possible to confirm this with the coarse scale at which petrels were, by necessity, tracked in our study. The exact nature of the interaction between the petrels and the icebergs remains to be elucidated, but recent reports of icebergs being visited by a wide range of foraging seabirds, including Antarctic petrels [16,18], supports the view that these structures constitute important features shaping seabirds' distribution. Icebergs are associated with higher ocean net primary productivity, especially in the SIZ and POOZ, suggesting a role of hotspots of biological activity for these features [8,54,[56][57][58].…”

Section: Discussionmentioning

confidence: 99%

“…Among those, the Antarctic petrel (Thalassoica antarctica) is a wide-ranging species and yearround resident of Antarctic waters [14]. Antarctic petrels generally forage in close association with sea ice, cold water-masses and icebergs [9,[14][15][16][17][18], where they capture primarily pelagic fish and crustaceans [19,20]. As such, any change in the icescape may have immediate consequences for petrel demography [21] and probably for their survival rate, as has been shown in other seabird species [22].…”

Section: Introductionmentioning

confidence: 99%

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Antarctic petrels ‘on the ice rocks’: wintering strategy of an Antarctic seabird

et al. 2020

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There is a paucity of information on the foraging ecology, especially individual use of sea-ice features and icebergs, over the non-breeding season in many seabird species. Using geolocators and stable isotopes, we defined the movements, distribution and diet of adult Antarctic petrels Thalassoica antarctica from the largest known breeding colony, the inland Svarthamaren, Antarctica. More specifically, we examined how sea-ice concentration and free-drifting icebergs affect the distribution of Antarctic petrels. After breeding, birds moved north to the marginal ice zone (MIZ) in the Weddell sector of the Southern Ocean, following its northward extension during freeze-up in April, and they wintered there in April–August. There, the birds stayed predominantly out of the water (60–80% of the time) suggesting they use icebergs as platforms to stand on and/or to rest. Feather δ 15 N values encompassed one full trophic level, indicating that birds fed on various proportions of crustaceans and fish/squid, most likely Antarctic krill Euphausia superba and the myctophid fish Electrona antarctica and/or the squid Psychroteuthis glacialis . Birds showed strong affinity for the open waters of the northern boundary of the MIZ, an important iceberg transit area, which offers roosting opportunities and rich prey fields. The strong association of Antarctic petrels with sea-ice cycle and icebergs suggests the species can serve, year-round, as a sentinel of environmental changes for this remote region.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Antarctic petrels ‘on the ice rocks’: wintering strategy of an Antarctic seabird

et al. 2020

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“…Crabeater swimming pods of juvenile individuals accompanied by a few adults ("rookeries") swimming around icebergs represented half the total number recorded [2]. Free-drifting icebergs constitute sites of high biological production, from phyto-and zooplankton to birds, seals and whales, in this case three birds and crabeater seals [1,2,11,[23][24][25]. Their influence includes areas of open water surrounding them for both seabirds and crabeater seal [1,2,25].…”

Section: Discussionmentioning

confidence: 99%

“…Free-drifting icebergs constitute sites of high biological production, from phyto-and zooplankton to birds, seals and whales, in this case three birds and crabeater seals [1,2,11,[23][24][25]. Their influence includes areas of open water surrounding them for both seabirds and crabeater seal [1,2,25].…”

Section: Discussionmentioning

confidence: 99%

Very Low Density and Biodiversity of Seabird and Marine Mammal at-sea Distribution in the Amundsen Sea, 2010

2021

JMSRO

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Our long-term study on the quantitative at-sea distribution of the upper trophic levels - seabirds and marine mammals - in polar ecosystems aims at quantifying the factors influencing their distribution as well as detecting possible spatial and temporal changes, with special attention to hydrography and global climate changes. During the ANT- XXVI/3 expedition of icebreaking RV Polarstern in February-March 2010, a total of 8,270 seabirds belonging to 15 identified species were recorded in the Amundsen Sea during 1,070 half-hour transect counts, with a mean of eight birds per count. The most numerous species were by far Antarctic petrel, Adélie penguin and snow petrel, which together accounted for more than 80% of all individuals of these species recorded. Substantial hotspots of seabirds perched on three icebergs, representing 44% of all observations: 85% of the Antarctic petrels and 40% of the snow petrels [1]. Without taking into account these data, the mean seabird number becomes five individuals per count, representing the lowest value registered in Antarctic seas. The most numerous pinniped was crabeater seal contributing 98% of the total of 2,350 individuals of four pinniped species [2]. Among cetaceans, the most abundant species were Antarctic Minke whale and fin whale (60% and 25% of the total of 170 individuals, four species). The maps allow for a visual comparison that is sufficient for the purposes of this article, reflecting the influence of hydrological features such as water masses and fronts, pack ice and ice edge, free drifting icebergs.

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“…Raiswell et al, 2006). Murray et al, 2011); ii) higher grazing pressure on enhanced stocks of phytoplankton by zooplankton within 2 km of icebergs (Vernet et al, 2011); iii) algal communities attached to icebergs comprising mainly of diatoms (Robinson et al, 2011); iv) macrozooplankton and microplankton communities around icebergs that are qualitatively and quantitatively different reflecting enhanced biological activity adjacent to ice free waters (Kaufmann et al, 2011); v) and higher sea bird densities and different composition within a few hundred meters of icebergs (Ruhl et al, 2011).…”

Section: Iron From Icebergsmentioning

confidence: 99%

Aeolian Iron and Its Contribution to Phytoplankton Production in McMurdo Sound, Southwest Ross Sea, Antarctica

Winton¹

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<p>Each summer the waters in McMurdo Sound (Lat. 77.5ºS; Long. 165ºE), south-western (SW) Ross Sea encounter vast phytoplankton blooms. This phenomenon is stimulated by the addition of bio-available iron (Fe) to an environment where phytoplankton growth is otherwise Fe-limited. One possible source of such Fe is aeolian sand and dust (ASD) which accumulates on sea ice and is released into the ocean during the summer melt season. The amount of bio-available Fe (i.e. the amount of Fe immedately accessible to phytoplankton) potentially supplied to the ocean by ASD depends on a number of factors including; the ASD flux into the ocean, its particle size distribution and Fe content. However, none of these parameters are well constrained in the SW Ross Sea region and, as a result, the significance of this Fe source in the biogeochemical cycle of phytoplankton growth remains to be quantified. This study focuses on an area (7400 km²) of Southern McMurdo Sound, one of the few areas where direct sampling of ASD that has accumulated on sea ice is possible. To evaluate the flux and solubility of Fe contained in ASD into McMurdo Sound, the mass accumulation rate and particle size of 70 surface snow samples and 3 shallow (3 m) firn cores from the nearby McMurdo Ice Shelf covering the period 2000 - 2008 have been analysed. Selected samples were also measured for total and soluble Fe, Sr and Nd isotopic ratios and mineralogy as a guide to Fe-fertilisation potential and provenance, respectively. Mass and particle size data show an exponential decrease in mass accumulation rate (from 26.00 g m⁻² yr⁻¹ to 0.70 g m⁻² yr⁻¹) and a decrease in modal particle size (from 130 to 69 μm) over a distance of 120 km from Southern McMurdo Sound northwards to Granite Harbour. Both these trends are consistent with ASD being dispersed northwards across the sea ice by southerly storms from an area of the McMurdo Ice Shelf, where submarine freezing and surface ablation have resulted in a surface covered with debris from the sea floor, known as the 'dirty ice' or 'debris bands' (Lat. 77.929ºS; Long. 165.505ºE) in Southern McMurdo Sound. This assertion is further supported by the Sr and Nd isotopic signature of ASD matching local source rocks and the presence of vesicular glass of Southern McMurdo Sound in all samples which also points to the debris bands as the origin of ASD in McMurdo Sound. Bio-available Fe is extremely difficult to quantify hence Fe solubility was used as an approximation in this thesis. Analysis of both total (i.e. particulate and soluble) and the percentage of soluble Fe in the 0.4 - 10 μm dust size fraction (i.e. the fraction most likely to become bio-available) by solution ICP-MS shows a narrow range of values; 3.84 ± 1.99 wt % and 9.42 ± 0.70 % respectively. Combining these values with mass accumulation rate estimates for the particles 0.4 - 10 μm in size, gives an annual soluble Fe flux for the region 500 km² north of the debris bands in McMurdo Sound of 0.55 mg m⁻² yr⁻¹ (9.89 μmol m⁻² yr⁻¹), with spatial variability largely determined by differences in mass accumulation rate. These fluxes are at least an order of magnitude greater than predicted in global dust deposition models for the Southern Ocean and measured in snow samples from East Antarctica. Furthermore, these values exceed the Fe threshold, estimated as 0.2 nM (Boyd and Abraham, 2001), required for phytoplankton growth following the simple dust-biota model of Boyd et al. (2010) and assuming the release of captured ASD in snow is instantaneous. Whilst not constrained in the present study, ASD sourced from the debris bands may be sufficiently widely dispersed, particularly during storm years, to contribute to Fe-fertilisation up to 1200 km from Southern McMurdo Sound. Short, ~10 year long, firn core records of mass accumulation and methylsuphonate concentration, a proxy for phytoplankton productivity, shows a close correspondence between the two during particularly stormy years. Whilst not demonstrating a cause-and-effect relationship, this observation suggests coastal ice cores may contain an important record of the interplay between climate, dust supply, Fe-fertilisation of near shore waters and phytoplankton productivity on decadal and longer timescales.</p>

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Seabird aggregation around free-drifting icebergs in the northwest Weddell and Scotia Seas

Cited by 17 publications

References 52 publications

Antarctic petrels ‘on the ice rocks’: wintering strategy of an Antarctic seabird

Antarctic petrels ‘on the ice rocks’: wintering strategy of an Antarctic seabird

Very Low Density and Biodiversity of Seabird and Marine Mammal at-sea Distribution in the Amundsen Sea, 2010

Aeolian Iron and Its Contribution to Phytoplankton Production in McMurdo Sound, Southwest Ross Sea, Antarctica

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