Winter foraging success of Southern Ocean predators in relation to stochastic variation in sea-ice extent and winter water formation
Metadata record for data from ASAC Project 2794 See the link below for public details on this project. Public: This study will use innovative technology to measure the winter spatial foraging patterns and net energy gain of adult female elephant seals (and potentially Weddell seals), while simultane...
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Australian Antarctic Data Centre
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| Online Access: | https://researchdata.ands.org.au/winter-foraging-success-water-formation/700029 https://doi.org/10.4225/15/554AACBF0C998 https://data.aad.gov.au/metadata/records/ASAC_2794 http://nla.gov.au/nla.party-617536 |
| Summary: | Metadata record for data from ASAC Project 2794 See the link below for public details on this project. Public: This study will use innovative technology to measure the winter spatial foraging patterns and net energy gain of adult female elephant seals (and potentially Weddell seals), while simultaneously providing high-resolution data on the physical nature of the water column in which the seals live. By combining biological and physical data with satellite derived sea-ice information, this study will improve our understanding of predator foraging success (and therefore mechanisms which regulate population trajectories) and provide physical oceanographers with fundamental data on the importance mechanisms that determine the winter ice and bottom water formation that under-pin the Antarctic marine ecosystem. Project objectives: The extent and nature of Antarctic winter sea ice is thought to have profound impacts on biological productivity, the recruitment of Antarctic krill, and the flow-on effects through the Antarctic marine food web. 1. Winter sea-ice formation is also hypothesised to play an important, yet highly-variable role in ocean circulation patterns through the production of cold, dense winter bottom water. 2. The mechanisms determining the inter-annual variation in winter ice formation are poorly understood, as are the complex feedback processes involved, but they are nonetheless recognised as being vulnerable to human-induced climate change. 3. Given the dynamically-linked nature of winter-ice and biological productivity, long-term climatic changes will have broad scale influences on Antarctic biota. This study will use innovative technological developments to quantify the response of one of the major Antarctic marine predators, the southern elephant seal (Mirounga leonina), to inter-annual variation in winter ice conditions. We will measure the winter spatial foraging patterns and net energy gain of adult female elephant seals while simultaneously providing high-resolution data on the physical nature of the water column in which the seals are living. The combination of these biological and physical data with satellite-derived sea-ice information will relate variation in the winter-ice to broad scale biological production through the foraging success (maternal investment and therefore demographic performance) of a top Antarctic marine predator, as well as providing physical oceanographers with fundamental data on the important mechanisms that determine the winter ice and bottom water formation that under-pin the Antarctic marine ecosystem. The specific objectives are to: 1. Measure the foraging performance of the seals in terms of spatially-specific net energy gain while at sea, in relation to intra- and inter-annual variation in sea-ice and oceanic processes. 2. Use newly-developed (and tested) animal-borne satellite-linked Conductivity-Temperature-Depth Satellite Relay Data Loggers (CTD-SRDLs) to provide oceanographic quality data on local physical characteristics (temperature and salinity). 3. Record fine-scale foraging parameters (dive depth, duration, swimming speed) using "Dead-Reckoning" Data Loggers (DRDLs) and feeding events using Stomach Temperature Sensors (STSs). 4. Integrate these data collected in years and regions of different winter ice extent and conditions. 5. Assess diet during the winter months using stable isotope and fatty acid signature analysis. 6. Combine the biological and physical information to refine current models of predator performance based on annual climatic features. These models will be used to examine a range of climate-change scenarios, initially for elephant seals but with a view to broadening the species application at a later stage. Taken from the 2008-2009 Progress Report: Progress against objectives: Due to logistic constraints, no satellite telemetry was conducted at Casey or Macquarie Island this year, but preliminary surveys of the region were conducted for both elephant and Weddell seals (see report for 2753). However we did deploy CTD satellite tags on elephant seals at Isles Kerguelen and Elephant Island to contribute to the IPY MEOP program. These animals either traversed the Southern Ocean to forage over the Antarctic continental shelf, or remained very close to their breeding island, indicating that even within a population there are markedly different foraging strategies. Taken from the 2010-2011 Progress Report: Public summary of the season progress: Due to pre-departure accident for one of the field team leaders we were unable to reach Casey this year to complete that component of the program. Forty CTD satellite tags were successfully deployed at Vestfold Hills in January and February 2011. These tags are currently still transmitting from foraging locations along the Antarctic continental shelf and the ice edge. Project 2695 (ASAC_2695) was incorporated into this project. An Access database containing data from this project is available for download at the provided URL. The data have also been loaded into the Australian Antarctic Data Centre's ARGOS tracking database. The database can be accessed at the provided URLs. |
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