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Henry Elderfield - One of the best experts on this subject based on the ideXlab platform.
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controls on stable isotope and trace metal uptake in neogloboquadrina pachyderma sinistral from an antarctic sea Ice Environment
2009Co-Authors: Katharine R Hendry, Rosalind E M Rickaby, Michael P Meredith, Henry ElderfieldAbstract:article The polar foraminifera Neogloboquadrina pachyderma (sinistral) dominates assemblages from the high latitude Southern Ocean, which plays a key role in determining past climate due to the tight linkage between Antarctic temperature and atmospheric CO2. Here, we use N. pachyderma (s.) harvested from sediment traps off the West Antarctic Peninsula to construct a seasonal time series for the calibration of calcite proxies in a high latitude seasonal sea-Ice Environment where temperature is decoupled from other Environmental parameters. We have used a combination of δ 18 OCaCO3 and δ 13 CCaCO3 to decipher the calcification temperature and salinity, which reflect that N. pachyderma (s.) live in surface waters throughout the year, and at the Ice-water interface in austral winter. Further, our results demonstrate that the uptake of trace metals into N. pachyderma (s.) calcite is influenced by secondary Environmental conditions in addition to temperature during periods of sea-Ice cover. We propose an elevated carbonate ion concentration at the Ice- water interface resulting from biological utilisation of CO2 could influence calcification in foraminifera. Our calculations suggest that for N. pachyderma (s.) Mg/Ca, Sr/Ca ratios and Li/Ca ratios are linear functions of calcification temperature and (CO3 2� ). N. pachyderma (s.) Mg/Ca ratios exhibit temperature sensitivity similar to previous studies (~10-20%/°C) and a sensitivity to (CO3 2� ) of ~1%/μmol kg �1 . Sr/Ca ratios are less sensitive to Environmental parameters, exhibiting ~5% increase/°C and ~0.5%/10 μmol kg �1 . The relationship between Li/Ca ratios and both temperature and (CO3 2� ) is less significant with ~10% increase in Li/Ca ratio/°C and 10 μmol kg �1 . We show how a multi-proxy approach could be used to constrain past high latitude surface
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controls on stable isotope and trace metal uptake in neogloboquadrina pachyderma sinistral from an antarctic sea Ice Environment
2009Co-Authors: Katharine R Hendry, Rosalind E M Rickaby, Michael P Meredith, Henry ElderfieldAbstract:The polar foraminifera Neogloboquadrina pachyderma (sinistral) dominates assemblages from the high latitude Southern Ocean, which plays a key role in determining past climate due to the tight linkage between Antarctic temperature and atmospheric CO2. Here, we use N. pachyderma (s.) harvested from sediment traps off the West Antarctic Peninsula to construct a seasonal time series for the calibration of calcite proxies in a high latitude seasonal sea-Ice Environment where temperature is decoupled from other Environmental parameters. We have used a combination of δ18OCaCO3 and δ 13CCaCO3 to decipher the calcification temperature and salinity, which reflect that N. pachyderma (s.) live in surface waters throughout the year, and at the Ice–water interface in austral winter. Further, our results demonstrate that the uptake of trace metals into N. pachyderma (s.) calcite is influenced by secondary Environmental conditions in addition to temperature during periods of sea-Ice cover. We propose an elevated carbonate ion concentration at the Ice–water interface resulting from biological utilisation of CO2 could influence calcification in foraminifera. Our calculations suggest that for N. pachyderma (s.) Mg/Ca, Sr/Ca ratios and Li/Ca ratios are linear functions of calcification temperature and [CO32−]. N. pachyderma (s.) Mg/Ca ratios exhibit temperature sensitivity similar to previous studies (~ 10–20%/°C) and a sensitivity to [CO32−] of ~ 1%/μmol kg− 1. Sr/Ca ratios are less sensitive to Environmental parameters, exhibiting ~ 5% increase/°C and ~ 0.5%/10 μmol kg− 1. The relationship between Li/Ca ratios and both temperature and [CO32−] is less significant with ~ 10% increase in Li/Ca ratio/°C and 10 μmol kg− 1. We show how a multi-proxy approach could be used to constrain past high latitude surface water temperature and [CO32−].
Randall W Davis - One of the best experts on this subject based on the ideXlab platform.
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homing tactics of weddell seals in the antarctic fast Ice Environment
2020Co-Authors: Lee A Fuiman, Terrie M Williams, Randall W DavisAbstract:Most activities of Weddell seals (Leptonychotes weddellii) occur during under-Ice dives that extend hundreds to thousands of meters and require the seals to hold their breath for 15 min or more. In the fast-Ice Environment of Antarctica, holes in the Ice where seals can surface to breathe are scarce. Consequently, seals must return to a previous breathing hole or locate a new one to avoid drowning; how they navigate underwater with such precision is not known. This study individually displaced ten seals, each fitted with an archival data logger, to unfamiliar locations and analyzed the three dimensional paths of voluntary dives to test eight predictions under four hypothesized way-finding tactics: geomagnetic sensitivity, path integration, pilotage, and hydrodynamic trail following. Analyses of dive tracks provided strong evidence that Weddell seals primarily used pilotage via visible, overhead features to return home during individual dives under Ice cover. Upon release at an unfamiliar location, long-distance diving began only after a period of short-distance diving. Outbound paths of dives progressively increased in distance from home. Homeward paths were remarkably straight and oriented directly toward home, or they traveled to a frequented route then turned toward home. Seventy-five percent of the frequented routes were directly below known linear disturbances in the snow on the top of the sea Ice. There was little evidence that seals used geomagnetic or hydrodynamic cues, nor that homing ability was hindered by low light levels (twilight). These results contribute to a growing body of literature indicating that animals can learn to use artificial, and sometimes ephemeral landmarks to guide their movements. How Weddell seals are able to dive during polar winter, with only starlight and moonlight to illuminate landmarks, remains unknown.
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structure of foraging dives by weddell seals at an offshore isolated hole in the antarctic fast Ice Environment
2007Co-Authors: Lee A Fuiman, Terrie M Williams, Kiersten M Madden, Randall W DavisAbstract:Abstract Knowledge of the biology and ecology of diving animals has been constrained by the inability to make direct observations of their underwater behaviour. We deployed an animal-borne video and data recorder on 10 adult Weddell seals (Leptonychotes weddellii) near Ross Island, McMurdo Sound, Antarctica, during the austral spring, to examine the structure of foraging dives. Three-dimensional dive profiles for 109 foraging dives were reconstructed, and nine behavioural states were identified based on geometry of the travel path and changes in speed and stroking. Five kinds of prey-related events were identified using video imagery. Most foraging was in midwater; rarer benthic foraging dives were especially distinctive. Successful and unsuccessful midwater foraging dives did not differ in energetic cost, but benthic foraging dives required significantly more energy than midwater dives and approached the seal's aerobic dive limit. We described the dominant sequence of behaviours in successful midwater, unsuccessful midwater, and unsuccessful benthic foraging dives. We also examined the dominant sequence leading to the first prey encounter in a dive and found that it usually followed an ascent, which in turn followed descent and/or horizontal swimming. We confirmed that discontinuous trajectories in time–depth profiles occur during midwater prey encounter. There were two kinds of descent behaviour (descent and meandering descent), both with reduced stroking and a large amount of gliding, which appeared to be when searching occurred. There is also some indication that increased amounts of gliding during descent behaviours could increase the seal's ability to capture prey by reducing the amount of self-generated noise. These findings provide a baseline for comparison with entirely free-ranging seals and for more detailed study of foraging strategies of diving seals.
Katharine R Hendry - One of the best experts on this subject based on the ideXlab platform.
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controls on stable isotope and trace metal uptake in neogloboquadrina pachyderma sinistral from an antarctic sea Ice Environment
2009Co-Authors: Katharine R Hendry, Rosalind E M Rickaby, Michael P Meredith, Henry ElderfieldAbstract:article The polar foraminifera Neogloboquadrina pachyderma (sinistral) dominates assemblages from the high latitude Southern Ocean, which plays a key role in determining past climate due to the tight linkage between Antarctic temperature and atmospheric CO2. Here, we use N. pachyderma (s.) harvested from sediment traps off the West Antarctic Peninsula to construct a seasonal time series for the calibration of calcite proxies in a high latitude seasonal sea-Ice Environment where temperature is decoupled from other Environmental parameters. We have used a combination of δ 18 OCaCO3 and δ 13 CCaCO3 to decipher the calcification temperature and salinity, which reflect that N. pachyderma (s.) live in surface waters throughout the year, and at the Ice-water interface in austral winter. Further, our results demonstrate that the uptake of trace metals into N. pachyderma (s.) calcite is influenced by secondary Environmental conditions in addition to temperature during periods of sea-Ice cover. We propose an elevated carbonate ion concentration at the Ice- water interface resulting from biological utilisation of CO2 could influence calcification in foraminifera. Our calculations suggest that for N. pachyderma (s.) Mg/Ca, Sr/Ca ratios and Li/Ca ratios are linear functions of calcification temperature and (CO3 2� ). N. pachyderma (s.) Mg/Ca ratios exhibit temperature sensitivity similar to previous studies (~10-20%/°C) and a sensitivity to (CO3 2� ) of ~1%/μmol kg �1 . Sr/Ca ratios are less sensitive to Environmental parameters, exhibiting ~5% increase/°C and ~0.5%/10 μmol kg �1 . The relationship between Li/Ca ratios and both temperature and (CO3 2� ) is less significant with ~10% increase in Li/Ca ratio/°C and 10 μmol kg �1 . We show how a multi-proxy approach could be used to constrain past high latitude surface
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controls on stable isotope and trace metal uptake in neogloboquadrina pachyderma sinistral from an antarctic sea Ice Environment
2009Co-Authors: Katharine R Hendry, Rosalind E M Rickaby, Michael P Meredith, Henry ElderfieldAbstract:The polar foraminifera Neogloboquadrina pachyderma (sinistral) dominates assemblages from the high latitude Southern Ocean, which plays a key role in determining past climate due to the tight linkage between Antarctic temperature and atmospheric CO2. Here, we use N. pachyderma (s.) harvested from sediment traps off the West Antarctic Peninsula to construct a seasonal time series for the calibration of calcite proxies in a high latitude seasonal sea-Ice Environment where temperature is decoupled from other Environmental parameters. We have used a combination of δ18OCaCO3 and δ 13CCaCO3 to decipher the calcification temperature and salinity, which reflect that N. pachyderma (s.) live in surface waters throughout the year, and at the Ice–water interface in austral winter. Further, our results demonstrate that the uptake of trace metals into N. pachyderma (s.) calcite is influenced by secondary Environmental conditions in addition to temperature during periods of sea-Ice cover. We propose an elevated carbonate ion concentration at the Ice–water interface resulting from biological utilisation of CO2 could influence calcification in foraminifera. Our calculations suggest that for N. pachyderma (s.) Mg/Ca, Sr/Ca ratios and Li/Ca ratios are linear functions of calcification temperature and [CO32−]. N. pachyderma (s.) Mg/Ca ratios exhibit temperature sensitivity similar to previous studies (~ 10–20%/°C) and a sensitivity to [CO32−] of ~ 1%/μmol kg− 1. Sr/Ca ratios are less sensitive to Environmental parameters, exhibiting ~ 5% increase/°C and ~ 0.5%/10 μmol kg− 1. The relationship between Li/Ca ratios and both temperature and [CO32−] is less significant with ~ 10% increase in Li/Ca ratio/°C and 10 μmol kg− 1. We show how a multi-proxy approach could be used to constrain past high latitude surface water temperature and [CO32−].
Lee A Fuiman - One of the best experts on this subject based on the ideXlab platform.
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homing tactics of weddell seals in the antarctic fast Ice Environment
2020Co-Authors: Lee A Fuiman, Terrie M Williams, Randall W DavisAbstract:Most activities of Weddell seals (Leptonychotes weddellii) occur during under-Ice dives that extend hundreds to thousands of meters and require the seals to hold their breath for 15 min or more. In the fast-Ice Environment of Antarctica, holes in the Ice where seals can surface to breathe are scarce. Consequently, seals must return to a previous breathing hole or locate a new one to avoid drowning; how they navigate underwater with such precision is not known. This study individually displaced ten seals, each fitted with an archival data logger, to unfamiliar locations and analyzed the three dimensional paths of voluntary dives to test eight predictions under four hypothesized way-finding tactics: geomagnetic sensitivity, path integration, pilotage, and hydrodynamic trail following. Analyses of dive tracks provided strong evidence that Weddell seals primarily used pilotage via visible, overhead features to return home during individual dives under Ice cover. Upon release at an unfamiliar location, long-distance diving began only after a period of short-distance diving. Outbound paths of dives progressively increased in distance from home. Homeward paths were remarkably straight and oriented directly toward home, or they traveled to a frequented route then turned toward home. Seventy-five percent of the frequented routes were directly below known linear disturbances in the snow on the top of the sea Ice. There was little evidence that seals used geomagnetic or hydrodynamic cues, nor that homing ability was hindered by low light levels (twilight). These results contribute to a growing body of literature indicating that animals can learn to use artificial, and sometimes ephemeral landmarks to guide their movements. How Weddell seals are able to dive during polar winter, with only starlight and moonlight to illuminate landmarks, remains unknown.
-
structure of foraging dives by weddell seals at an offshore isolated hole in the antarctic fast Ice Environment
2007Co-Authors: Lee A Fuiman, Terrie M Williams, Kiersten M Madden, Randall W DavisAbstract:Abstract Knowledge of the biology and ecology of diving animals has been constrained by the inability to make direct observations of their underwater behaviour. We deployed an animal-borne video and data recorder on 10 adult Weddell seals (Leptonychotes weddellii) near Ross Island, McMurdo Sound, Antarctica, during the austral spring, to examine the structure of foraging dives. Three-dimensional dive profiles for 109 foraging dives were reconstructed, and nine behavioural states were identified based on geometry of the travel path and changes in speed and stroking. Five kinds of prey-related events were identified using video imagery. Most foraging was in midwater; rarer benthic foraging dives were especially distinctive. Successful and unsuccessful midwater foraging dives did not differ in energetic cost, but benthic foraging dives required significantly more energy than midwater dives and approached the seal's aerobic dive limit. We described the dominant sequence of behaviours in successful midwater, unsuccessful midwater, and unsuccessful benthic foraging dives. We also examined the dominant sequence leading to the first prey encounter in a dive and found that it usually followed an ascent, which in turn followed descent and/or horizontal swimming. We confirmed that discontinuous trajectories in time–depth profiles occur during midwater prey encounter. There were two kinds of descent behaviour (descent and meandering descent), both with reduced stroking and a large amount of gliding, which appeared to be when searching occurred. There is also some indication that increased amounts of gliding during descent behaviours could increase the seal's ability to capture prey by reducing the amount of self-generated noise. These findings provide a baseline for comparison with entirely free-ranging seals and for more detailed study of foraging strategies of diving seals.
Rosalind E M Rickaby - One of the best experts on this subject based on the ideXlab platform.
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controls on stable isotope and trace metal uptake in neogloboquadrina pachyderma sinistral from an antarctic sea Ice Environment
2009Co-Authors: Katharine R Hendry, Rosalind E M Rickaby, Michael P Meredith, Henry ElderfieldAbstract:article The polar foraminifera Neogloboquadrina pachyderma (sinistral) dominates assemblages from the high latitude Southern Ocean, which plays a key role in determining past climate due to the tight linkage between Antarctic temperature and atmospheric CO2. Here, we use N. pachyderma (s.) harvested from sediment traps off the West Antarctic Peninsula to construct a seasonal time series for the calibration of calcite proxies in a high latitude seasonal sea-Ice Environment where temperature is decoupled from other Environmental parameters. We have used a combination of δ 18 OCaCO3 and δ 13 CCaCO3 to decipher the calcification temperature and salinity, which reflect that N. pachyderma (s.) live in surface waters throughout the year, and at the Ice-water interface in austral winter. Further, our results demonstrate that the uptake of trace metals into N. pachyderma (s.) calcite is influenced by secondary Environmental conditions in addition to temperature during periods of sea-Ice cover. We propose an elevated carbonate ion concentration at the Ice- water interface resulting from biological utilisation of CO2 could influence calcification in foraminifera. Our calculations suggest that for N. pachyderma (s.) Mg/Ca, Sr/Ca ratios and Li/Ca ratios are linear functions of calcification temperature and (CO3 2� ). N. pachyderma (s.) Mg/Ca ratios exhibit temperature sensitivity similar to previous studies (~10-20%/°C) and a sensitivity to (CO3 2� ) of ~1%/μmol kg �1 . Sr/Ca ratios are less sensitive to Environmental parameters, exhibiting ~5% increase/°C and ~0.5%/10 μmol kg �1 . The relationship between Li/Ca ratios and both temperature and (CO3 2� ) is less significant with ~10% increase in Li/Ca ratio/°C and 10 μmol kg �1 . We show how a multi-proxy approach could be used to constrain past high latitude surface
-
controls on stable isotope and trace metal uptake in neogloboquadrina pachyderma sinistral from an antarctic sea Ice Environment
2009Co-Authors: Katharine R Hendry, Rosalind E M Rickaby, Michael P Meredith, Henry ElderfieldAbstract:The polar foraminifera Neogloboquadrina pachyderma (sinistral) dominates assemblages from the high latitude Southern Ocean, which plays a key role in determining past climate due to the tight linkage between Antarctic temperature and atmospheric CO2. Here, we use N. pachyderma (s.) harvested from sediment traps off the West Antarctic Peninsula to construct a seasonal time series for the calibration of calcite proxies in a high latitude seasonal sea-Ice Environment where temperature is decoupled from other Environmental parameters. We have used a combination of δ18OCaCO3 and δ 13CCaCO3 to decipher the calcification temperature and salinity, which reflect that N. pachyderma (s.) live in surface waters throughout the year, and at the Ice–water interface in austral winter. Further, our results demonstrate that the uptake of trace metals into N. pachyderma (s.) calcite is influenced by secondary Environmental conditions in addition to temperature during periods of sea-Ice cover. We propose an elevated carbonate ion concentration at the Ice–water interface resulting from biological utilisation of CO2 could influence calcification in foraminifera. Our calculations suggest that for N. pachyderma (s.) Mg/Ca, Sr/Ca ratios and Li/Ca ratios are linear functions of calcification temperature and [CO32−]. N. pachyderma (s.) Mg/Ca ratios exhibit temperature sensitivity similar to previous studies (~ 10–20%/°C) and a sensitivity to [CO32−] of ~ 1%/μmol kg− 1. Sr/Ca ratios are less sensitive to Environmental parameters, exhibiting ~ 5% increase/°C and ~ 0.5%/10 μmol kg− 1. The relationship between Li/Ca ratios and both temperature and [CO32−] is less significant with ~ 10% increase in Li/Ca ratio/°C and 10 μmol kg− 1. We show how a multi-proxy approach could be used to constrain past high latitude surface water temperature and [CO32−].
