scholarly journals Exploration during early life: distribution, habitat and orientation preferences in juvenile king penguins

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
F. Orgeret ◽  
C. Péron ◽  
M. R. Enstipp ◽  
K. Delord ◽  
H. Weimerskirch ◽  
...  
Keyword(s):  
Early Life ◽  
Habitat Preferences ◽  
Austral Summer ◽  
First Year ◽  
Apex Predators ◽  
Life History Stages ◽  
Wintering Area ◽  
Circumpolar Current ◽  
Foraging Skills ◽  
The Antarctic

Abstract Background The early life of marine apex predators is poorly known, particularly for diving species. The orientation and foraging skills are presumably less developed in juveniles than in adults, especially during their first year at sea when juveniles might disperse further than adults. Methods Over two years of monitoring, we tracked the movements of 17 juvenile king penguins (Aptenodytes patagonicus, ~ 1 year old) using satellite relay tags from Crozet Archipelago (Southern Indian Ocean), starting when birds left their natal colony for the first time. For comparison we also tagged 6 non-breeding adults, which at that stage, similar to juveniles, are unhampered by reproductive constraints and might roam further than breeders. We used a combination of cluster analysis and habitat modelling to investigate and compare the movement patterns and habitat use of experienced (non-breeding adults) and non-experienced (juveniles) individuals. Results While juvenile penguins and non-breeding adults followed similar routes, the movements by adults started later in the season and ranged over a considerably smaller area than juveniles. Net squared displacement analysis revealed that both groups did not move to a specific wintering area. Changes in direction of juveniles in respect to their departure island were similar and synchronous for both years. Habitat models revealed that foraging behaviour was affected by environmental variables such as wind or current speeds, sea surface temperature, or oceanic productivity, for both stages. Analysis of tracks revealed that birds moved predominately perpendicular or against the main direction of the Antarctic Circumpolar Current and the prevailing wind during austral summer (juveniles only) and autumn (juveniles and non-breeding adults). However, both juveniles and adults were more likely to move against the prevailing winds if productivity increased along their trajectories. Conclusions The exceptional duration of our tracking study provided unprecedented insights into the distribution, habitat preferences and orientation of two poorly known life history stages of an expert avian diver. Our study suggests that juveniles might use both innate and learnt skills to reach profitable foraging areas during their first year at sea, which is critical in long-lived species.

scholarly journals Albedo of the ice covered Weddell and Bellingshausen Seas

2012 ◽  
Vol 6 (2) ◽  
pp. 479-491 ◽  
Author(s):  
A. I. Weiss ◽  
J. C. King ◽  
T. A. Lachlan-Cope ◽  
R. S. Ladkin
Keyword(s):  
Sea Ice ◽  
Surface Albedo ◽  
Austral Summer ◽  
Open Water ◽  
Weddell Sea ◽  
First Year ◽  
Pack Ice ◽  
Bellingshausen Sea ◽  
The Mean ◽  
The Antarctic

Abstract. This study investigates the surface albedo of the sea ice areas adjacent to the Antarctic Peninsula during the austral summer. Aircraft measurements of the surface albedo, which were conducted in the sea ice areas of the Weddell and Bellingshausen Seas show significant differences between these two regions. The averaged surface albedo varied between 0.13 and 0.81. The ice cover of the Bellingshausen Sea consisted mainly of first year ice and the sea surface showed an averaged sea ice albedo of αi = 0.64 ± 0.2 (± standard deviation). The mean sea ice albedo of the pack ice area in the western Weddell Sea was αi = 0.75 ± 0.05. In the southern Weddell Sea, where new, young sea ice prevailed, a mean albedo value of αi = 0.38 ± 0.08 was observed. Relatively warm open water and thin, newly formed ice had the lowest albedo values, whereas relatively cold and snow covered pack ice had the highest albedo values. All sea ice areas consisted of a mixture of a large range of different sea ice types. An investigation of commonly used parameterizations of albedo as a function of surface temperature in the Weddell and Bellingshausen Sea ice areas showed that the albedo parameterizations do not work well for areas with new, young ice.

scholarly journals Otolith chemistry indicates population structuring by the Antarctic Circumpolar Current

2008 ◽  
Vol 65 (2) ◽  
pp. 135-146 ◽  
Author(s):  
Julian R Ashford ◽  
Cynthia M Jones ◽  
Eileen E Hofmann ◽  
Inigo Everson ◽  
Carlos A Moreno ◽  
...  
Keyword(s):  
Population Structure ◽  
South America ◽  
Early Life ◽  
Antarctic Circumpolar Current ◽  
Large Scale ◽  
Advective Transport ◽  
Complex Population ◽  
Population Structuring ◽  
Circumpolar Current ◽  
The Antarctic

Large-scale transport of seawater in ocean currents may generate spatially complex population structure through the advection of life stages of marine fish species. To test this, we compared the chemistry of otolith nuclei from Patagonian toothfish (Dissostichus eleginoides), presently managed as spatially discrete populations corresponding to fishing management areas along the Antarctic Circumpolar Current (ACC), which transports water eastward around the Southern Ocean. The chemistry of otolith nuclei, laid down during early life, differed significantly between fishing areas off South America and the Antarctic and between some Antarctic areas. However, we found significant discrepancies from expectation for a population structure corresponding to fishing areas. We also found evidence of four groups of fish with different early life chemistry: one associated with South America and three Antarctic groups showing mixing consistent with advective transport along the ACC. These results suggest that toothfish populations are structured by their physical environment; population abundance and persistence may rely on a restricted number of breeding members with access to spawning grounds, whereas fisheries may rely substantially on nonbreeding vagrants transported from fishing areas upstream.

scholarly journals Diapycnal Mixing in the Antarctic Circumpolar Current

2011 ◽  
Vol 41 (1) ◽  
pp. 241-246 ◽  
Author(s):  
J. R. Ledwell ◽  
L. C. St. Laurent ◽  
J. B. Girton ◽  
J. M. Toole
Keyword(s):  
Antarctic Circumpolar Current ◽  
Austral Summer ◽  
Drake Passage ◽  
Meridional Overturning Circulation ◽  
Velocity Shear ◽  
Reference Spectrum ◽  
Diapycnal Mixing ◽  
Diapycnal Diffusivity ◽  
Circumpolar Current ◽  
The Antarctic

Abstract The vertical dispersion of a tracer released on a density surface near 1500-m depth in the Antarctic Circumpolar Current west of Drake Passage indicates that the diapycnal diffusivity, averaged over 1 yr and over tens of thousands of square kilometers, is (1.3 ± 0.2) × 10−5 m2 s−1. Diapycnal diffusivity estimated from turbulent kinetic energy dissipation measurements about the area occupied by the tracer in austral summer 2010 was somewhat less, but still within a factor of 2, at (0.75 ± 0.07) × 10−5 m2 s−1. Turbulent diapycnal mixing of this intensity is characteristic of the midlatitude ocean interior, where the energy for mixing is believed to derive from internal wave breaking. Indeed, despite the frequent and intense atmospheric forcing experienced by the Southern Ocean, the amplitude of finescale velocity shear sampled about the tracer was similar to background amplitudes in the midlatitude ocean, with levels elevated to only 20%–50% above the Garrett–Munk reference spectrum. These results add to a long line of evidence that diapycnal mixing in the interior middepth ocean is weak and is likely too small to dictate the middepth meridional overturning circulation of the ocean.

scholarly journals Nonlinear Differential Equations Modeling the Antarctic Circumpolar Current

2021 ◽  
Vol 23 (4) ◽  
Author(s):  
Jifeng Chu ◽  
Kateryna Marynets
Keyword(s):  
Fixed Point ◽  
Differential Equations ◽  
Boundary Conditions ◽  
Topological Degree ◽  
Antarctic Circumpolar Current ◽  
Fixed Point Theorems ◽  
Nonlinear Differential Equations ◽  
Existence Results ◽  
Circumpolar Current ◽  
The Antarctic

AbstractThe aim of this paper is to study one class of nonlinear differential equations, which model the Antarctic circumpolar current. We prove the existence results for such equations related to the geophysical relevant boundary conditions. First, based on the weighted eigenvalues and the theory of topological degree, we study the semilinear case. Secondly, the existence results for the sublinear and superlinear cases are proved by fixed point theorems.

scholarly journals Levels of Predominant Intestinal Microorganisms in 1 Month-Old Full-Term Babies and Weight Gain During the First Year of Life

Nutrients ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 2412
Author(s):  
Sonia González ◽  
Marta Selma-Royo ◽  
Silvia Arboleya ◽  
Cecilia Martínez-Costa ◽  
Gonzalo Solís ◽  
...  
Keyword(s):  
Weight Gain ◽  
Gut Microbiota ◽  
Early Life ◽  
Later Life ◽  
Full Term ◽  
First Year ◽  
Term Infants ◽  
Term Newborns ◽  
Infant Weight Gain ◽  
First Year Of Life

The early life gut microbiota has been reported to be involved in neonatal weight gain and later infant growth. Therefore, this early microbiota may constitute a target for the promotion of healthy neonatal growth and development with potential consequences for later life. Unfortunately, we are still far from understanding the association between neonatal microbiota and weight gain and growth. In this context, we evaluated the relationship between early microbiota and weight in a cohort of full-term infants. The absolute levels of specific fecal microorganisms were determined in 88 vaginally delivered and 36 C-section-delivered full-term newborns at 1 month of age and their growth up to 12 months of age. We observed statistically significant associations between the levels of some early life gut microbes and infant weight gain during the first year of life. Classifying the infants into tertiles according to their Staphylococcus levels at 1 month of age allowed us to observe a significantly lower weight at 12 months of life in the C-section-delivered infants from the highest tertile. Univariate and multivariate models pointed out associations between the levels of some fecal microorganisms at 1 month of age and weight gain at 6 and 12 months. Interestingly, these associations were different in vaginally and C-section-delivered babies. A significant direct association between Staphylococcus and weight gain at 1 month of life was observed in vaginally delivered babies, whereas in C-section-delivered infants, lower Bacteroides levels at 1 month were associated with higher later weight gain (at 6 and 12 months). Our results indicate an association between the gut microbiota and weight gain in early life and highlight potential microbial predictors for later weight gain.

scholarly journals An Assessment of ERA5 Reanalysis for Antarctic Near-Surface Air Temperature

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 217
Author(s):  
Jiangping Zhu ◽  
Aihong Xie ◽  
Xiang Qin ◽  
Yetang Wang ◽  
Bing Xu ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Antarctic Peninsula ◽  
Austral Summer ◽  
Correlation Coefficients ◽  
East Antarctica ◽  
West Antarctica ◽  
Austral Spring ◽  
Reanalysis Dataset ◽  
Near Surface ◽  
The Antarctic

The European Center for Medium-Range Weather Forecasts (ECMWF) released its latest reanalysis dataset named ERA5 in 2017. To assess the performance of ERA5 in Antarctica, we compare the near-surface temperature data from ERA5 and ERA-Interim with the measured data from 41 weather stations. ERA5 has a strong linear relationship with monthly observations, and the statistical significant correlation coefficients (p < 0.05) are higher than 0.95 at all stations selected. The performance of ERA5 shows regional differences, and the correlations are high in West Antarctica and low in East Antarctica. Compared with ERA5, ERA-Interim has a slightly higher linear relationship with observations in the Antarctic Peninsula. ERA5 agrees well with the temperature observations in austral spring, with significant correlation coefficients higher than 0.90 and bias lower than 0.70 °C. The temperature trend from ERA5 is consistent with that from observations, in which a cooling trend dominates East Antarctica and West Antarctica, while a warming trend exists in the Antarctic Peninsula except during austral summer. Generally, ERA5 can effectively represent the temperature changes in Antarctica and its three subregions. Although ERA5 has bias, ERA5 can play an important role as a powerful tool to explore the climate change in Antarctica with sparse in situ observations.

scholarly journals Eddy Phase Speeds in a Two-Layer Model of Quasigeostrophic Baroclinic Turbulence with Applications to Ocean Observations

2016 ◽  
Vol 46 (6) ◽  
pp. 1963-1985 ◽  
Author(s):  
Lei Wang ◽  
Malte Jansen ◽  
Ryan Abernathey
Keyword(s):  
Practical Importance ◽  
Phase Speed ◽  
Wave Theory ◽  
Inverse Cascade ◽  
Barotropic Mode ◽  
Eddy Fluxes ◽  
Circumpolar Current ◽  
The Antarctic ◽  
Ocean Observations ◽  
Shed Light

AbstractThe phase speed spectrum of ocean mesoscale eddies is fundamental to understanding turbulent baroclinic flows. Since eddy phase propagation has been shown to modulate eddy fluxes, an understanding of eddy phase speeds is also of practical importance for the development of improved eddy parameterizations for coarse resolution ocean models. However, it is not totally clear whether and how linear Rossby wave theory can be used to explain the phase speed spectra in various weakly turbulent flow regimes. Using linear analysis, theoretical constraints are identified that control the eddy phase speed in a two-layer quasigeostrophic (QG) model. These constraints are then verified in a series of nonlinear two-layer QG simulations, spanning a range of parameters with potential relevance to the ocean. In the two-layer QG model, the strength of the inverse cascade exerts an important control on the eddy phase speed. If the inverse cascade is weak, the phase speed spectrum is reasonably well approximated by the phase speed of the linearly most unstable mode. A significant inverse cascade instead leads to barotropization, which in turn leads to mean phase speeds closer to those of barotropic-mode Rossby waves. The two-layer QG results are qualitatively consistent with the observed eddy phase speed spectra in the Antarctic Circumpolar Current and may also shed light on the interpretation of phase speed spectra observed in other regions.

Sign in / Sign up

Export Citation Format

Share Document