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  • 1
    In: Frontiers in Ecology and Evolution, Frontiers Media SA, Vol. 10 ( 2023-1-23)
    Abstract: Sea ice is a key habitat in the high latitude Southern Ocean and is predicted to change in its extent, thickness and duration in coming decades. The sea-ice cover is instrumental in mediating ocean–atmosphere exchanges and provides an important substrate for organisms from microbes and algae to predators. Antarctic krill, Euphausia superba, is reliant on sea ice during key phases of its life cycle, particularly during the larval stages, for food and refuge from their predators, while other small grazers, including copepods and amphipods, either live in the brine channel system or find food and shelter at the ice-water interface and in gaps between rafted ice blocks. Fish, such as the Antarctic silverfish Pleuragramma antarcticum , use platelet ice (loosely-formed frazil crystals) as an essential hatching and nursery ground. In this paper, we apply the framework of the Marine Ecosystem Assessment for the Southern Ocean (MEASO) to review current knowledge about relationships between sea ice and associated primary production and secondary consumers, their status and the drivers of sea-ice change in this ocean. We then use qualitative network modelling to explore possible responses of lower trophic level sea-ice biota to different perturbations, including warming air and ocean temperatures, increased storminess and reduced annual sea-ice duration. This modelling shows that pelagic algae, copepods, krill and fish are likely to decrease in response to warming temperatures and reduced sea-ice duration, while salp populations will likely increase under conditions of reduced sea-ice duration and increased number of days of & gt;0°C. Differences in responses to these pressures between the five MEASO sectors were also explored. Greater impacts of environmental pressures on ice-related biota occurring presently were found for the West and East Pacific sectors (notably the Ross Sea and western Antarctic Peninsula), with likely flow-on effects to the wider ecosystem. All sectors are expected to be impacted over coming decades. Finally, we highlight priorities for future sea ice biological research to address knowledge gaps in this field.
    Type of Medium: Online Resource
    ISSN: 2296-701X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
    detail.hit.zdb_id: 2745634-1
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  • 2
    In: Frontiers in Ecology and Evolution, Frontiers Media SA, Vol. 9 ( 2022-6-17)
    Abstract: In the Southern Ocean, several zooplankton taxonomic groups, euphausiids, copepods, salps and pteropods, are notable because of their biomass and abundance and their roles in maintaining food webs and ecosystem structure and function, including the provision of globally important ecosystem services. These groups are consumers of microbes, primary and secondary producers, and are prey for fishes, cephalopods, seabirds, and marine mammals. In providing the link between microbes, primary production, and higher trophic levels these taxa influence energy flows, biological production and biomass, biogeochemical cycles, carbon flux and food web interactions thereby modulating the structure and functioning of ecosystems. Additionally, Antarctic krill ( Euphausia superba ) and various fish species are harvested by international fisheries. Global and local drivers of change are expected to affect the dynamics of key zooplankton species, which may have potentially profound and wide-ranging implications for Southern Ocean ecosystems and the services they provide. Here we assess the current understanding of the dominant metazoan zooplankton within the Southern Ocean, including Antarctic krill and other key euphausiid, copepod, salp and pteropod species. We provide a systematic overview of observed and potential future responses of these taxa to a changing Southern Ocean and the functional relationships by which drivers may impact them. To support future ecosystem assessments and conservation and management strategies, we also identify priorities for Southern Ocean zooplankton research.
    Type of Medium: Online Resource
    ISSN: 2296-701X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2745634-1
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  • 3
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 4 ( 2017-09-26)
    Type of Medium: Online Resource
    ISSN: 2296-7745
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2017
    detail.hit.zdb_id: 2757748-X
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  • 4
    In: Polar Biology, Springer Science and Business Media LLC, Vol. 31, No. 7 ( 2008-6), p. 837-851
    Type of Medium: Online Resource
    ISSN: 0722-4060 , 1432-2056
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2008
    detail.hit.zdb_id: 1478942-5
    detail.hit.zdb_id: 584850-7
    SSG: 12
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  • 5
    In: Global Change Biology, Wiley, Vol. 20, No. 10 ( 2014-10), p. 3004-3025
    Abstract: Antarctic and Southern Ocean ( ASO ) marine ecosystems have been changing for at least the last 30 years, including in response to increasing ocean temperatures and changes in the extent and seasonality of sea ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species changing differently in different regions. This article reviews current and expected changes in ASO physical habitats in response to climate change. It then reviews how these changes may impact the autecology of marine biota of this polar region: microbes, zooplankton, salps, Antarctic krill, fish, cephalopods, marine mammals, seabirds, and benthos. The general prognosis for ASO marine habitats is for an overall warming and freshening, strengthening of westerly winds, with a potential pole‐ward movement of those winds and the frontal systems, and an increase in ocean eddy activity. Many habitat parameters will have regionally specific changes, particularly relating to sea ice characteristics and seasonal dynamics. Lower trophic levels are expected to move south as the ocean conditions in which they are currently found move pole‐ward. For Antarctic krill and finfish, the latitudinal breadth of their range will depend on their tolerance of warming oceans and changes to productivity. Ocean acidification is a concern not only for calcifying organisms but also for crustaceans such as Antarctic krill; it is also likely to be the most important change in benthic habitats over the coming century. For marine mammals and birds, the expected changes primarily relate to their flexibility in moving to alternative locations for food and the energetic cost of longer or more complex foraging trips for those that are bound to breeding colonies. Few species are sufficiently well studied to make comprehensive species‐specific vulnerability assessments possible. Priorities for future work are discussed.
    Type of Medium: Online Resource
    ISSN: 1354-1013 , 1365-2486
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 2020313-5
    SSG: 12
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  • 6
    In: Human Reproduction, Oxford University Press (OUP), Vol. 36, No. 3 ( 2021-02-18), p. 624-635
    Abstract: What are the cohort trends of women undergoing oocyte cryopreservation (OC)? SUMMARY ANSWER There has been a dramatic increase in OC cycles undertaken each year since 2010, and the demographics of women accessing OC has shifted to a younger age group, but so far very few women have returned to use their cryopreserved oocytes in treatments. WHAT IS KNOWN ALREADY Although OC, as a method of fertility preservation, is offered around the world, global data are lacking on who is accessing OC, who is returning to thaw oocytes and whether these trends are changing. STUDY DESIGN, SIZE, DURATION A trinational retrospective cohort study was performed of 31 191 OC cycles and 972 oocyte thaw (OT) cycles undertaken in the USA (2010–2016) and 3673 OC and 517 OT cycles undertaken in Australia/New Zealand (Aus/NZ; 2010–2015). PARTICIPANTS/MATERIALS, SETTING, METHODS Data were obtained from the USA Society for Assisted Reproductive Technology (SART) national registry and the Australian and New Zealand Assisted Reproduction Database (ANZARD). De-identified data were requested on all autologous oocyte freeze-all cycles and all cycles where autologous oocytes were thawed to be used in a treatment cycle for the time periods of interest. MAIN RESULTS AND THE ROLE OF CHANCE In both the USA and Aus/NZ, there has been a dramatic rise in the number of OC cycles performed each year (+880% in the USA from 2010 to 2016 and +311% in Aus/NZ from 2010 to 2015). Across both regions, most women undergoing OC were aged in their late 30s, but the average age decreased over time (USA: 36.7 years vs 34.7 years in 2010 and 2016, respectively). The number of women returning for thaw cycles was low (USA: 413 in 2016, Aus/NZ: 141 in 2015) and most thaw cycles (47%) across both regions involved oocytes that were frozen for & lt;6 months. In the USA, a higher proportion of cycles resulted in a live birth when only thawed oocytes were used, compared to cycles that combined thawed oocytes with fresh oocytes (25% vs 11%, respectively; P  & lt; 0.001). Age at retrieval influenced live birth rate in the USA; 38% of thaw cycles started in women who stored oocytes when aged ≤35 years resulted in a live birth, whereas only 16% resulted in a live birth for women who stored oocytes when aged ≥36 years. Similar data were unobtainable from Aus/NZ. LIMITATIONS, REASONS FOR CAUTION There were limitations associated with both the SART and ANZARD data outputs received. The format in which the ANZARD data were provided, and the inconsistencies seen amongst cycle reporting in the SART dataset, restricted data interpretation. For example, both datasets did not provide a clear indication as to why women were undergoing OC and it was not possible to accurately calculate duration of storage for thaw cycles in the USA. We also did not obtain details on embryo quality from either database and acknowledge that embryo quality and subsequent outcome (embryo freezing or discard) would be of interest, especially when considering the efficacy of OC. WIDER IMPLICATIONS OF THE FINDINGS The data show that there is widespread demand for OC, and it is increasingly undertaken by younger women; however, the limitations encountered in the dataset support the need for a shift to a more uniform approach to data collection and presentation by large databases, worldwide. STUDY FUNDING/COMPETING INTEREST(S) This study received funding from the Fertility Society of Australia to support the ANZARD data extraction. M.J. is supported by an Australian Government Research Training Program Scholarship stipend. The authors declare no competing interests. TRIAL REGISTRATION NUMBER N/A.
    Type of Medium: Online Resource
    ISSN: 0268-1161 , 1460-2350
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2021
    detail.hit.zdb_id: 1484864-8
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  • 7
    In: Journal of Climate, American Meteorological Society, Vol. 37, No. 7 ( 2024-04-01), p. 2157-2178
    Abstract: A main source of regional climate change uncertainty is the large disparity across models in simulating the atmospheric circulation response to global warming. Using the latest suite of global climate models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6), a storyline approach is adopted to derive physically plausible scenarios of Antarctic climate change for 2070–99, according to Shared Socioeconomic Pathway SSP5-8.5. These storylines correspond to differences in the simulated amount of seasonal sea ice loss and either (i) the delay in the summertime stratospheric polar vortex (SPV) breakdown or (ii) wintertime SPV strengthening, which together constitute robust drivers of the response pattern to future climate change. Such changes combined are known to exert a strong control over the Southern Hemisphere midlatitude jet stream, which we quantify as collectively explaining up to 70% of the variance in jet response in summer and 35% in winter. For summer, the expected strengthening and displacement of the tropospheric jet stream varies between a ∼1 and 2 m s −1 increase and ∼2°–4° poleward shift, respectively, across storylines. In both seasons, a larger strengthening of the jet is correlated with less Antarctic warming. By contrast, the response in precipitation is more consistent but still strongly attenuated by large-scale dynamics. We find that an increase in high-latitude precipitation around Antarctica is more pronounced for storylines characterized by a greater poleward jet shift, particularly in summer. Our results highlight the usefulness of the storyline approach in illustrating model uncertainty and understanding the processes that determine the spread in projected Antarctic regional climate response. Significance Statement Uncertainty in future climate predictions for the Antarctic is dominated by the unknown response of the large-scale (global) atmospheric circulation. In characterizing such uncertainty, plausible outcomes of climate response (storylines) are generated from the organization of model projections according to the amount of simulated seasonal sea ice loss and the delay in summertime breakdown/winter strengthening of the stratospheric westerly circulation (polar vortex). The intensity and location of the tropospheric jet stream is strongly dependent on both factors, which strongly influences the near-surface climate response over Antarctica. We find that the simulated amount that Antarctic air temperatures increase by in the future (to the end of the century) is intrinsically related to the projected intensification of the Southern Hemisphere tropospheric jet, varying by a factor of 2 or more across storylines for summer. Storylines with greater jet strengthening are associated with less Antarctic warming (reduced poleward advection of air masses from lower latitudes). Similar differences are found for changes in jet position, which we note has a much stronger control on mid- to high-latitude precipitation response. This includes both an enhanced wetting response around Antarctica and drying response farther equatorward, for storylines characterized by a greater poleward jet shift.
    Type of Medium: Online Resource
    ISSN: 0894-8755 , 1520-0442
    RVK:
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2024
    detail.hit.zdb_id: 246750-1
    detail.hit.zdb_id: 2021723-7
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  • 8
    In: Frontiers in Ecology and Evolution, Frontiers Media SA, Vol. 9 ( 2021-10-14)
    Abstract: Globally important services are supported by Southern Ocean ecosystems, underpinned by the structure, function, and dynamics of complex interconnected and regionally distinctive food webs. These food webs vary in response to a combination of physical and chemical processes that alter productivity, species composition and the relative abundance and dynamics of organisms. Combined with regional and seasonal variability, climate-induced changes and human activities have and are expected to continue to drive important structural and functional changes to Southern Ocean food webs. However, our current understanding of food web structure, function, status, and trends is patchy in space and time, and methods for systematically assessing and comparing community-level responses to change within and across regional and temporal scales are not well developed. Insights gained from food web modelling studies—ranging from theoretical analyses of ecosystem resilience and adaptation, to qualitative and quantitative descriptions of the system—can assist in resolving patterns of energy flow and the ecological mechanisms that drive food web structure, function, and responses to drivers (such as fishing and climate change). This understanding is required to inform robust management strategies to conserve Southern Ocean food webs and the ecosystem services they underpin in the face of change. This paper synthesises the current state of knowledge regarding Southern Ocean pelagic food webs, highlighting the distinct regional food web characteristics, including key drivers of energy flow, dominant species, and network properties that may indicate system resilience. In particular, the insights, gaps, and potential integration of existing knowledge and Southern Ocean food web models are evaluated as a basis for developing integrated food web assessments that can be used to test the efficacy of alternative management and policy options. We discuss key limitations of existing models for assessing change resulting from various drivers, summarise priorities for model development and identify that significant progress could be made to support policy by advancing the development of food web models coupled to projected biogeochemical models, such as in Earth System models.
    Type of Medium: Online Resource
    ISSN: 2296-701X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2745634-1
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  • 9
    Online Resource
    Online Resource
    Wiley ; 1999
    In:  Journal of Animal Ecology Vol. 68, No. 5 ( 1999-09), p. 893-905
    In: Journal of Animal Ecology, Wiley, Vol. 68, No. 5 ( 1999-09), p. 893-905
    Type of Medium: Online Resource
    ISSN: 0021-8790 , 1365-2656
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 1999
    detail.hit.zdb_id: 2006616-8
    SSG: 12
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  • 10
    Online Resource
    Online Resource
    The Royal Society ; 2007
    In:  Philosophical Transactions of the Royal Society B: Biological Sciences Vol. 362, No. 1488 ( 2007-12-29), p. 2187-2189
    In: Philosophical Transactions of the Royal Society B: Biological Sciences, The Royal Society, Vol. 362, No. 1488 ( 2007-12-29), p. 2187-2189
    Abstract: The Antarctic biota has evolved over the last 100 million years in increasingly isolated and cold conditions. As a result, Antarctic species, from micro-organisms to vertebrates, have adapted to life at extremely low temperatures, including changes in the genome, physiology and ecological traits such as life history. Coupled with cycles of glaciation that have promoted speciation in the Antarctic, this has led to a unique biota in terms of biogeography, patterns of species distribution and endemism. Specialization in the Antarctic biota has led to trade-offs in many ecologically important functions and Antarctic species may have a limited capacity to adapt to present climate change. These include the direct effects of changes in environmental parameters and indirect effects of increased competition and predation resulting from altered life histories of Antarctic species and the impacts of invasive species. Ultimately, climate change may alter the responses of Antarctic ecosystems to harvesting from humans. The unique adaptations of Antarctic species mean that they provide unique models of molecular evolution in natural populations. The simplicity of Antarctic communities, especially from terrestrial systems, makes them ideal to investigate the ecological implications of climate change, which are difficult to identify in more complex systems.
    Type of Medium: Online Resource
    ISSN: 0962-8436 , 1471-2970
    RVK:
    Language: English
    Publisher: The Royal Society
    Publication Date: 2007
    detail.hit.zdb_id: 1462620-2
    SSG: 12
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