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Mark A. Hindell - One of the best experts on this subject based on the ideXlab platform.

  • Climate influences on female survival in a declining population of southern elephant seals (Mirounga leonina)
    'Wiley', 2021
    Co-Authors: Sophia Volzke, Mark A. Hindell, Harry R Burton, Clive R Mcmahon, Simon J. Wotherspoon
    Abstract:

    Abstract The Southern Ocean has been disproportionately affected by climate change and is therefore an ideal place to study the influence of changing environmental conditions on ecosystems. Changes in the demography of predator populations are indicators of broader shifts in food web structure, but long‐term data are required to study these effects. Southern elephant seals (Mirounga leonina) from Macquarie Island have consistently decreased in population size while all other major populations across the Southern Ocean have recently stabilized or are increasing. Two long‐term mark‐recapture studies (1956–1967 and 1993–2009) have monitored this population, which provides an opportunity to investigate demographic performance over a range of climatic conditions. Using a 9‐state matrix population model, we estimated climate influences on female survival by incorporating two major climatic indices into our model: The Southern Annular Mode (SAM) and the Southern Oscillation Index (SOI). Our best model included a 1 year lagged effect of SAM and an unlagged SOI as covariates. A positive relationship with SAM1 (lagged) related the previous year's SAM with juvenile survival, potentially due to changes in local prey availability surrounding Macquarie Island. The unlagged SOI had a negative effect on both juvenile and adult seals, indicating that sea ice dynamics and access to foraging grounds on the East Antarctic continental shelf could explain the different contributions of ENSO events on the survival of females in this population

  • modelling southern elephant seals Mirounga leonina using an individual based model coupled with a dynamic energy budget
    PLOS ONE, 2018
    Co-Authors: Merel Goedegebuure, Mark A. Hindell, Stuart Corney, Clive R Mcmahon, Jessica Melbournethomas
    Abstract:

    Higher trophic-level species are an integral component of any marine ecosystem. Despite their importance, methods for representing these species in end-to-end ecosystem models often have limited representation of life histories, energetics and behaviour. We built an individual-based model coupled with a dynamic energy budget for female southern elephant seals Mirounga leonina to demonstrate a method for detailed representation of marine mammals. We aimed to develop a model which could i) simulate energy use and life histories, as well as breeding traits of southern elephant seals in an emergent manner, ii) project a stable population over time, and iii) have realistic population dynamics and structure based on emergent life history features (such as age at first breeding, lifespan, fecundity and (yearling) survival). We evaluated the model's ability to represent a stable population over long time periods (>10 generations), including the sensitivity of the emergent properties to variations in key parameters. Analyses indicated that the model is sensitive to changes in resource availability and energy requirements for the transition from pup to juvenile, and juvenile to adult stage. This was particularly the case for breeding success and yearling survival. This model is suitable for use as a standalone tool for investigating the impacts of changes to behaviour and population responses of southern elephant seals.

  • five decades on use of historical weaning size data reveals that a decrease in maternal foraging success underpins the long term decline in population of southern elephant seals Mirounga leonina
    PLOS ONE, 2017
    Co-Authors: Ella Clausius, Clive R Mcmahon, Mark A. Hindell
    Abstract:

    The population of Southern elephant seals (Mirounga leonina) at Macquarie Island has declined since the 1960s, and is thought to be due to changing oceanic conditions leading to reductions in the foraging success of Macquarie Island breeding females. To test this hypothesis, we used a 55-year-old data set on weaning size of southern elephant seals to quantify a decrease in weaning size from a period of population stability in 1950s to its present state of on-going decline. Being capital breeders, the size of elephant seal pups at weaning is a direct consequence of maternal foraging success in the preceding year. During the 1940-1950s, the mean of female pups at weaning was similar between the Heard and Macquarie Island populations, while the snout-tail-length length of male weaners from Heard Island were longer than their conspecifics at Macquarie Island. Additionally, the snout-tail-length of pups at weaning decreased by 3cm between the 1950s and 1990s in the Macquarie Island population, concurrent with the observed population decline. Given the importance of weaning size in determining first-year survival and recruitment rates, the decline in the size at weaning suggests that the decline in the Macquarie Island population has, to some extent, been driven by reduced maternal foraging success, consequent declines in the size of pups at weaning, leading to reduced first-year survival rates and recruitment of breeding females into the population 3 to 4 years later.

  • Bio-physical characterisation of polynyas as a key foraging habitat for juvenile male southern elephant seals (Mirounga leonina) in Prydz Bay, East Antarctica
    PLoS ONE, 2017
    Co-Authors: Veda Malpress, Sophie Bestley, Sara Labrousse, Stuart Corney, Dirk Welsford, Michael Sumner, Mark A. Hindell
    Abstract:

    Antarctic coastal polynyas are persistent open water areas in the sea ice zone, and regions of high biological productivity thought to be important foraging habitat for marine predators. This study quantified southern elephant seal (Mirounga leonina) habitat use within and around the polynyas of the Prydz Bay region (63˚E– 88˚E) in East Antarctica, and examined the bio-physical characteristics structuring polynyas as foraging habitat. Output from a cli-matological regional ocean model was used to provide context for in situ temperature-salin-ity vertical profiles collected by tagged elephant seals and to characterise the physical properties structuring polynyas. Biological properties were explored using remotely-sensed surface chlorophyll (Chl-a) and, qualitatively, historical fish assemblage data. Spatially gridded residence time of seals was examined in relation to habitat characteristics using generalized additive mixed models. The results showed clear polynya usage during early autumn and increasingly concentrated usage during early winter. Bathymetry, Chl-a, surface net heat flux (representing polynya location), and bottom temperature were identified as significant bio-physical predictors of the spatio-temporal habitat usage. The findings from this study confirm that the most important marine habitats for juvenile male southern elephant seals within Prydz Bay region are polynyas. A hypothesis exists regarding the seasonal evolution of primary productivity, coupling from surface to subsurface productivity and supporting elevated rates of secondary production in the upper water column during summer autumn. An advancement to this hypothesis is proposed here, whereby this bio-physical coupling is likely to extend throughout the water column as it becomes fully convected during autumn-winter, to also promote pelagic-benthic linkages important for benthic foraging within polynyas.

  • combining bio logging and fatty acid signature analysis indicates spatio temporal variation in the diet of the southern elephant seal Mirounga leonina
    Journal of Experimental Marine Biology and Ecology, 2014
    Co-Authors: Janaya Banks, Clive R Mcmahon, Maryanne Lea, Stephen Wall, Mark A. Hindell
    Abstract:

    Quantifying the foraging ecology of apex predators is crucial for understanding the predator–prey interactions in marine ecosystems. This is particularly important in the Southern Ocean ecosystem, where year-round studies are logistically and financially impractical. Detailed investigations into the diet of wide-ranging southern hemisphere marine predators, therefore, need to be quantified spatio-temporally. We coupled tracking data with fatty acid signature analysis (FASA) to investigate the foraging ecology of a wide-ranging Southern Ocean marine predator, the southern elephant seal (Mirounga leonina). Seal foraging areas varied spatially and over time, but seals concentrated their activities in three broad geographic regions (i) off the East Antarctic Continental Shelf (S-ACC), (ii) at the edge of the pack ice north of the Ross Sea (SE-RS) and (iii) north of the Sub-Antarctic Front (SE-SAF). There were significant differences in the fatty acid (FA) composition of the blubber from the seals that used these different regions. Seals foraging in the SE-SAF had blubber high in short chained mono-unsaturated fatty acids (SC-MUFAs), compared to those from the S-ACC and SE-RS habitats, which contained more poly-unsaturated fatty acids (PUFAs). Comparisons with FAs of known prey species in the region indicated that blubber collected from seals using the shelf and pelagic habitats (i.e. S-ACC and SE-SAF) were likely to have higher proportions of fish in the diet and, conversely, those from the pack-ice habitat (i.e. SE-RS) were more likely to have a cosmopolitan diet, i.e. an evenly mixed diet of fish and squid. Seal diet also varied annually, within the shelf and pelagic habitats changing from a diet relatively high in fish, to a diet relatively high in squid. Coupling tracking data with FASA is a powerful technique to investigate the spatio-temporal variations in the diet of wide-ranging marine predators.

Christophe Guinet - One of the best experts on this subject based on the ideXlab platform.

  • Diving Behavior of Mirounga leonina: A Functional Data Analysis Approach
    Frontiers in Marine Science, 2020
    Co-Authors: Morgan Godard, Christophe Guinet, Baptiste Picard, Claude Manté, David Nerini
    Abstract:

    The diving behavior of southern elephant seals, Mirounga leonina, is investigated through the analysis of time-depth dive profiles. The originality of this work is to consider dive profiles as continuous curves. For this purpose, a Functional Data Analysis (FDA) approach is proposed for the shape analysis of a collection of dive profiles. Complexity of dive shapes is characterized by a mixture of three main shape variations accounting for about 80% of the entire variability: U or V shape, vertical depth variability during the bottom time, and skewed left or right. Model-based clustering allows the identification of eight dive shape clusters in a quick and automated way. Connection between shape patterns and classical descriptors, as well as the number of prey capture events, is achieved, showing that the clusters are coherent to specific foraging behaviors previously identified in the literature labeled as drift, exploratory and active dives. Finally, FDA is compared to classical methods relying on the computation of discrete dive descriptors. Results show that taking the shape of the dive as a whole is more resilient to corrupted or incomplete sampled data. FDA is, therefore, an efficient tool adapted for processing and comparing dive data with different sampling frequencies and for improving the quality and the accuracy of transmitted data.

  • acoustic measurements of post dive cardiac responses in southern elephant seals Mirounga leonina during surfacing at sea
    The Journal of Experimental Biology, 2017
    Co-Authors: Louise Day, Joffrey Joumaa, Julien Bonnel, Christophe Guinet
    Abstract:

    ABSTRACT Measuring physiological data in free-ranging marine mammals remains challenging, owing to their far-ranging foraging habitat. Yet, it is important to understand how these divers recover from effort expended underwater, as marine mammals can perform deep and recurrent dives. Among them, southern elephant seals ( Mirounga leonina ) are one of the most extreme divers, diving continuously at great depth and for long duration while travelling over large distances within the Southern Ocean. To determine how they manage post-dive recovery, we deployed hydrophones on four post-breeding female southern elephant seals. Cardiac data were extracted from sound recordings when the animal was at the surface, breathing. Mean heart rate at the surface was 102.4±4.9 beats min −1 and seals spent on average 121±20 s breathing. During these surface intervals, the instantaneous heart rate increased with time. Elephant seals are assumed to drastically slow their heart rate (bradycardia) while they are deep underwater, and increase it (tachycardia) during the ascent towards the surface. Our finding suggests that tachycardia continues while the animal stays breathing at the surface. Also, the measured mean heart rate at the surface was unrelated to the duration and swimming effort of the dive prior to the surface interval. Recovery (at the surface) after physical effort (underwater) appears to be related to the overall number of heart beats performed at the surface, and therefore total surface duration. Southern elephant seals recover from dives by adjusting the time spent at the surface rather than their heart rate.

  • How elephant seals (Mirounga leonina) adjust their fine scale horizontal movement and diving behaviour in relation to prey encounter rate
    PLoS ONE, 2016
    Co-Authors: Yves Le Bras, Joffrey Jouma'a, Baptiste Picard, Christophe Guinet
    Abstract:

    Understanding the diving behaviour of diving predators in relation to concomitant prey distribution could have major practical applications in conservation biology by allowing the assessment of how changes in fine scale prey distribution impact foraging efficiency and ultimately population dynamics. The southern elephant seal (Mirounga leonina, hereafter SES), the largest phocid, is a major predator of the southern ocean feeding on myctophids and cephalopods. Because of its large size it can carry bio-loggers with minimal disturbance. Moreover, it has great diving abilities and a wide foraging habitat. Thus, the SES is a well suited model species to study predator diving behaviour and the distribution of ecologically important prey species in the Southern Ocean. In this study, we examined how SESs adjust their diving behaviour and horizontal movements in response to fine scale prey encounter densities using high resolution accelerometers, magnetometers, pressure sensors and GPS loggers. When high prey encounter rates were encountered, animals responded by (1) diving and returning to the surface with steeper angles, reducing the duration of transit dive phases (thus improving dive efficiency), and (2) exhibiting more horizontally and vertically sinuous bottom phases. In these cases, the distance travelled horizontally at the surface was reduced. This behaviour is likely to counteract horizontal displacement from water currents, as they try to remain within favourable prey patches. The prey encounter rate at the bottom of dives decreased with increasing diving depth, suggesting a combined effect of decreased accessibility and prey density with increasing depth. Prey encounter rate also decreased when the bottom phases of dives were spread across larger vertical extents of the water column. This result suggests that the vertical aggregation of prey can regulate prey density, and as a consequence impact the foraging success of SESs. To our knowledge, this is one of only a handful of studies showing how the vertical distributions and structure of prey fields influence the prey encounter rates of a diving predator.

  • integrative modelling of animal movement incorporating in situ habitat and behavioural information for a migratory marine predator
    Proceedings of The Royal Society B: Biological Sciences, 2013
    Co-Authors: Sophie Bestley, Ian D Jonsen, Mark A. Hindell, Christophe Guinet, Jean-benoît Charrassin
    Abstract:

    A fundamental goal in animal ecology is to quantify how environmental (and other) factors influence individual movement, as this is key to understanding responsiveness of populations to future change. However, quantitative interpretation of individual-based telemetry data is hampered by the complexity of, and error within, these multi-dimensional data. Here, we present an integrative hierarchical Bayesian state-space modelling approach where, for the first time, the mechanistic process model for the movement state of animals directly incorporates both environmental and other behavioural information, and observation and process model parameters are estimated within a single model. When applied to a migratory marine predator, the southern elephant seal (Mirounga leonina), we find the switch from directed to resident movement state was associated with colder water temperatures, relatively short dive bottom time and rapid descent rates. The approach presented here can have widespread utility for quantifying movement–behaviour (diving or other)–environment relationships across species and systems.

  • Identifying foraging events in deep diving southern elephant seals, Mirounga leonina, using acceleration data loggers
    Deep Sea Research Part II: Topical Studies in Oceanography, 2013
    Co-Authors: S.l. Gallon, Jean-benoît Charrassin, Christophe Guinet, Frédéric Bailleul, Charles-andré Bost, Yves Handrich, Mark A. Hindell
    Abstract:

    Southern elephant seals (Mirounga leonina) range widely throughout the Southern Ocean and are associated with important habitats (e.g., ice edges, shelf) where they accumulate energy to fuel their reproductive efforts on land. Knowledge of the fine scale foraging behaviour used to garner this energy, however, is limited. For the first time, acceleration loggers were deployed on three adult southern elephant seals during a translocation study at Kerguelen Island. The aims of the study were to (1) identify prey capture attempts using 2-D accelerometer tags deployed on the head of southern elephant seals, (2) compare the number of foraging dives identified by simple dive depth profiles and accelerometer profiles and (3) compare dive characteristics between prey encounter and non-prey encounter dives. The 2-D loggers recorded depth every second, surge and heave accelerations at 8 or 16 Hz and were carried for periods between 23 and 121 h. Rapid head movements were interpreted to be associated with prey encounter events. Acceleration data detected possible prey encounter events in 39-52% of dives whilst 67-80% of dives were classified as foraging dives when using dive depth profiles alone. Prey encounters occurred in successive dives during days and nights and lasted between tenths of a second and 7.6 min. Binomial linear mixed effect models showed that seals were diving significantly deeper and increased both descent rate and bottom duration when encountering prey. Dive duration, however, did not significantly increase during dives with prey encounters. These results are in accordance with optimal foraging theory, which predicts that deep divers should increase both their transit rates and the time spent at depth when a profitable prey patch is encountered. These findings indicate that this technique is promising as it more accurately detects possible prey encounter events compared with dive depth profiles alone and thus provides a better understanding of seal foraging strategies.

Harry R Burton - One of the best experts on this subject based on the ideXlab platform.

  • Climate influences on female survival in a declining population of southern elephant seals (Mirounga leonina)
    'Wiley', 2021
    Co-Authors: Sophia Volzke, Mark A. Hindell, Harry R Burton, Clive R Mcmahon, Simon J. Wotherspoon
    Abstract:

    Abstract The Southern Ocean has been disproportionately affected by climate change and is therefore an ideal place to study the influence of changing environmental conditions on ecosystems. Changes in the demography of predator populations are indicators of broader shifts in food web structure, but long‐term data are required to study these effects. Southern elephant seals (Mirounga leonina) from Macquarie Island have consistently decreased in population size while all other major populations across the Southern Ocean have recently stabilized or are increasing. Two long‐term mark‐recapture studies (1956–1967 and 1993–2009) have monitored this population, which provides an opportunity to investigate demographic performance over a range of climatic conditions. Using a 9‐state matrix population model, we estimated climate influences on female survival by incorporating two major climatic indices into our model: The Southern Annular Mode (SAM) and the Southern Oscillation Index (SOI). Our best model included a 1 year lagged effect of SAM and an unlagged SOI as covariates. A positive relationship with SAM1 (lagged) related the previous year's SAM with juvenile survival, potentially due to changes in local prey availability surrounding Macquarie Island. The unlagged SOI had a negative effect on both juvenile and adult seals, indicating that sea ice dynamics and access to foraging grounds on the East Antarctic continental shelf could explain the different contributions of ENSO events on the survival of females in this population

  • resource partitioning through oceanic segregation of foraging juvenile southern elephant seals Mirounga leonina
    Oecologia, 2005
    Co-Authors: Iain C Field, Corey J A Bradshaw, Harry R Burton, Michael D Sumner, Mark A. Hindell
    Abstract:

    In highly dynamic and unpredictable environments such as the Southern Ocean, species that have evolved behaviors that reduce the effects of intra-specific competition may have a selective advantage. This is particularly true when juveniles face disadvantages when foraging due to morphological or physiological limitation, which is the case for many marine mammals. We tracked the at-sea movements of 48 juvenile southern elephant seals (Mirounga leonina) between the ages of 1 and 4 years from the population at Macquarie Island using locations derived from recorded light levels. There were significant differences in the total amount of the Southern Ocean covered by the different age-groups. The younger seals used a smaller area than the older seals. On average, the younger individuals also made more trips to sea than the older seals and did not travel as far on each trip. Females spent more time at sea than males and there were no significant differences between the total areas used by male and females. In summary, younger seals remained closer to the island at all times, and they spent more time in more northerly regions that older seals. These differences in behavior created temporal and spatial segregation between juveniles of different ages. Therefore, we suggest that these temporal and spatial separations help to avoid intra-specific competition for resources on land, space on beaches, and at-sea foraging areas. Such modifications of haul-out timing and behavior enable them to exploit a patchy and unpredictable environment.

  • population status trends and a re examination of the hypotheses explaining the recent declines of the southern elephant seal Mirounga leonina
    Mammal Review, 2005
    Co-Authors: Mark A. Hindell, Harry R Burton, Corey J A Bradshaw, Marthán N. Bester, Clive R Mcmahon
    Abstract:

    Between the 1950s and 1990s the southern elephant seal Mirounga leonina underwent large decreases in population size throughout most of its breeding range in the Southern Ocean. While current population estimates suggest a recent recovery, some breeding populations have continued to decrease in recent years (Macquarie and Marion Islands), others have either remained stable (South Georgia, Kerguelen and Heard Island) or have increased (Peninsula Valdes, Argentina). 2. Intrinsic hypotheses for patterns of regional decline include factors that are affected by density-dependent mechanisms: (i) paucity of males, (ii) population 'overshoot' and (iii) pandemic disease. Extrinsic hypotheses include (iv) predation, (v) competition with fisheries concerns, (vi) interspecific competition, (vii) environmental change and (viii) human distur- bance. Of the eight hypotheses proposed and examined here, we conclude that three can be discounted (i, v, viii), three are unlikely, but may require more testing (ii, iii, iv) and two are plausible (vi, vii). 3. The interspecific competition hypothesis is difficult to test because it requires the simul- taneous monitoring of species that overlap directly with elephant seals, many of which have not been identified or little is known. However, an analysis of the relationship between log variance and log abundance (Taylor's power law) for populations of southern and northern elephant seals suggests that interspecific competition is not a significant factor in the decline of the southern elephant seal. 4. The hypothesis that decreases in southern elephant seal populations between the 1950s and 1990s were caused by the environmental change is the easiest to test and most plausible of the hypotheses. We propose a framework by which to test this hypothesis to determine how food availability affects individual survival.

  • temporal changes in the quality of hot iron brands on elephant seal Mirounga leonina pups
    Wildlife Research, 2004
    Co-Authors: John Van Den Hoff, Harry R Burton, Corey J A Bradshaw, Iain C Field, Michael D Sumner, Clive R Mcmahon
    Abstract:

    Hot-iron brands were used to mark permanently 14 000 six-week-old southern elephant seal (Mirounga leonina L.) pups at Macquarie Island between 1993 and 2000. We assessed temporal changes in the quality of 4932 brands applied in 1998 and 1999 to determine the duration of the brand wound, and the relationships between brand healing, brand readability and the amount of skin and hair damage peripheral to the brand characters. Most (98%) brand wounds were healed within one year. Brand-mark healing, peripheral skin damage and brand readability were significantly (P 95%) for the marked population. The mean number of brand characters with peripheral skin damage decreased significantly over the same period. The seal’s annual hair and skin moult is the process that contributed most to the healing of brand wounds. We also assessed our branding technique to determine whether any of the features we measured contributed to a poor-quality brand. Excessive pressure used during brand-iron application is the most probable cause of unsightly peripheral skin damage, but this damage is short lived.

  • effects of age size and condition of elephant seals Mirounga leonina on their intravenous anaesthesia with tiletamine and zolazepam
    Veterinary Record, 2002
    Co-Authors: Iain C Field, Corey J A Bradshaw, Clive R Mcmahon, J J Harrington, Harry R Burton
    Abstract:

    Southern elephant seals (Mirounga leonina) were caught as part of a long-term demographic study on Macquarie Island. Over 18 months, 1033 seals were caught by hand and anaesthetised intravenously with a 1:1 mixture of tiletamine and zolazepam. Assessments were made of the effects of variations in the body condition and age at capture of the seals on the characteristics of their anaesthesia, including induction time and weighted recovery time. The size and condition of the seals were assessed by morphometric and ultrasound measurements. Weighted recovery times decreased as the body condition and age of the seals increased, but there were no residual effects of sex. There were no fatalities, and no periods of apnoea longer than five minutes were recorded. In individual seals there was a significant increase in weighted recovery time with successive captures.

Elton Pinto Colares - One of the best experts on this subject based on the ideXlab platform.

  • scientific note corynosoma spp acanthocephala polymorphidae in Mirounga leonina pinnipedia phocidae of south shetlands islands a new host for corynosoma cetaceum
    2014
    Co-Authors: Tony Silveira, Ricardo Berteaux Robaldo, Adalto Bianchini, Elton Pinto Colares, Monica Mathias, Costa Muelbert, P E Martinez, Eliane Pereira, Luisa Schifino Valente
    Abstract:

    Corynosoma bullosum is a parasite of pinnipeds while Corynosoma cetaceum is considered a parasite of cetaceans. Until now, there were no records of parasitism by C. cetaceum in phocids. This study reports C. bullosum and the first record of C. cetaceum in Mirounga leonina from Antarctica.

  • lactational transfer of pcbs and chlorinated pesticides in pups of southern elephant seals Mirounga leonina from antarctica
    Chemosphere, 2009
    Co-Authors: Kleber Campos Miranda Filho, Ricardo Berteaux Robaldo, Elton Pinto Colares, Chris D Metcalfe, Tracy L Metcalfe, Monica Muelbert, Pablo Elias Martinez, Adalto Bianchini
    Abstract:

    Seven pairs of southern elephant seals (Mirounga leonina) pups and their dams were sampled during the late weaning season among a breeding population of seals on Elephant Island in Antarctica. The blubber of the pups and the milk and blubber of their dams were analyzed for lipid-normalized concentrations of PCBs and organochlorines compounds in order to evaluate the lactational transfer of these contaminants. The lipid-normalized concentrations in these tissues were in the ppb range (i.e., ngg(-1) lipid). The levels of contaminants in southern elephant seals were low in comparison with residues that have been reported in pinnipeds from the northern hemisphere. The relative tissue concentrations of the analytes measured followed the pattern: SigmaDDT>mirex>SigmaPCB>Sigmachlordane>HCB>heptachlor epoxide>dieldrin>methoxychlor>SigmaHCH>other organochlorines. The very high DDE/SigmaDDT ratio (0.91) in the blubber of dams and pups was an indicative of long-term, extremely distant pollution. On the other hand, the relatively high levels of some other organochlorine pesticides (e.g. mirex, heptachlor epoxide, dieldrin, methoxychor) may reflect the continued use of these insecticides in developing countries located in the southern hemisphere. For most of the analytes measured, the lipid-normalized concentrations were lower in pup blubber and in the milk than in the maternal blubber. Lactational transfer rates were dependent on the logK(ow) (octanol/water partition coefficient) values of the analytes measured, less lipophilic compounds being more readily transferred to the pups by the lactational route.

  • residues of persistent organochlorine contaminants in southern elephant seals Mirounga leonina from elephant island antarctica
    Environmental Science & Technology, 2007
    Co-Authors: Kleber Campos Mirandafilho, Ricardo Berteaux Robaldo, Elton Pinto Colares, Chris D Metcalfe, Tracy L Metcalfe, Monica Muelbert, Pablo Elias Martinez, Adalto Bianchini
    Abstract:

    Contamination of blubber tissues by organochlorine pesticides (OC) and PCBs was assessed in female and male pups and juveniles, as well as in adult females and subdominant adult males of the Southern elephant seal, Mirounga leonina, from Elephant Island in the Antarctic Peninsula. All residues of persistent organochlorine contaminants analyzed were found in blubber samples, except for beta-HCH, endosulfan II, endrin, heptachlor, and aldrin. The relative concentrations of the analytes detected were sigmaDDT > sigmaPCB > sigmachlordane > mirex > dieldrin > HCB> sigmaendosulfan > methoxychlor > sigmaHCHs > other OC pesticides. OC and PCBs concentrations were 1 or 2 orders of magnitude lower than those found in pinnipeds from northern hemisphere. The ratio sigmaDDT/sigmaPCB was higher in southern elephant seals. The relative importance of some OC residues indicates that pesticides used either currently or in the recent past in countries in the southern hemisphere are the sources of contamination in the Antarctic region. Data showed that concentrations of contaminants generally increased from pups < juveniles < adults and suggested that pups accumulated contaminants through transfer from the mother seals via transplacental and lactational routes.

  • serum leptin concentration during the terrestrial phase of the southern elephant seal Mirounga leonina carnivora phocidae
    General and Comparative Endocrinology, 2004
    Co-Authors: C Guilherme, P E Martinez, Ricardo Berteaux Robaldo, Adalto Bianchini, Elton Pinto Colares
    Abstract:

    This study aimed to verify the serum leptin concentration during the terrestrial phase of the Southern elephant seal (Mirounga leonina) on Elephant Island (South Shetlands, Antarctica). Sera from 25 adult Southern elephant seals were analyzed. Leptin concentration was determined using the 1 2 5 I radioimmunoassay method. Total protein, triglycerides, and cholesterol concentration were measured by spectrophotometric methods. Seals were grouped by sex and their physiological status (reproducing or molting seals). In reproducing seals, serum concentrations of leptin, total protein, triglycerides, and cholesterol were, respectively, 9.33 ′ 1.97 ng/ml, 6.87 ′ 0.09 g/dl, 98.26 ′ 2.12 mg/dl, and 232.17 ′ 41.18 mg/dl in males and 5.30 ′ 1.36 ng/ml, 6.44 ′ 0.29 g/dl, 109.01 ′ 3.34 mg/dl, and 219.20 ′ 26.65 in females (mean ′ I SD). In molting seals, these values were 2.35 ′ 1.51 ng/ml, 7.42 ′ 0.25 mg/dl, 321.10 ′ 20.01 mg/dl, and 244.66 ′ 22.24 mg/dl in males and 2.94 ′ 1.89 ng/ml, 7.88 ′ 0.46 mg/dl, 197.54 mg/dl, and 224.55 ′ 16.70 mg/dl in females. In both males and females, there were no significant differences (P > 0.05) in total protein and cholesterol concentration between reproducing and molting seals. However, both males and females showed higher leptin concentration (P < 0.05) and lower triglyceride concentration (P < 0.05) in the reproductive period than in the molt period. In the reproductive period, it was expected that the Southern elephant seal shows an inhibited hunger sensation, mobilizes stored energy, and stimulates the HPG axis. Results from the present study support this hypothesis and suggest that this strategy may be effected by the hormonal stimulation of leptin.

Negrete Javier - One of the best experts on this subject based on the ideXlab platform.

  • Morphology of the tympanic-basicranial region in Mirounga leonina (Phocidae, Carnivora), postnatal ontogeny and sexual dimorphism
    2021
    Co-Authors: Loza, Cleopatra Mara, Negrete Javier, Scarano, Alejo Carlos, Soibelzon, Leopoldo Héctor, Carlini, Alfredo Armando
    Abstract:

    The auditory region of pinnipeds has seldom been described. Here we describe and analyze the ontogenetic trajectory of the tympanic bulla of the southern elephant seal, Mirounga leonina (Phocidae, Mammalia). This species is extremely sexually dimorphic and highly polygynous (organized in harems). We examined 118 specimens, arranged in three age classes (CI, CII, and CIII), ranging from newborn to adults (males and females). To analyze the overall size and shape of the tympanic bulla we performed a geometric morphometric analysis including 87 skulls. Females reach definitive shape and size of the bulla at earlier ontogenetic stages than males, in agreement with their earlier involvement in reproductive activities. The internal anatomy of the tympanic region (e.g. form and extension of the paries) does not show remarkable differences between sexes or age classes. The greatest differences between age classes are related to bone thickness, resulting from the apposition of new annual layers. An examination of possible sex-related external differences among age classes shows significant shape differences between males and females in CIII. The morphology observed in neonates is conserved across all individuals from CI, which included specimens up to 1 year old. Clear morphological differences were observed between CI individuals, on one hand, and CII individuals plus CIII females on the other. During cranial development of both male and females, the glenoid cavity expands and compresses the bulla; this condition reaches its maximum expression in CIII males. CIII males showed the greatest morphological differences, with respect to both CI and CII individuals, and CIII females.Facultad de Ciencias Naturales y Muse

  • Estructura de las interacciones agonísticas entre machos de elefante marino del sur (Mirounga leonina) durante la temporada reproductiva en isla 25 de Mayo, Antártida
    2019
    Co-Authors: Pfoh Malena, Ciai, Dante Nahuel, Rossi, Juan B., Durante M., Ferrari, Héctor Ricardo, Negrete Javier
    Abstract:

    Durante la temporada reproductiva los machos del elefante marino del sur (Mirounga leonina) compiten por el acceso a las hembras mediante interacciones agonísticas (IA), que establecen una jerarquía entre el ejecutor de la primera pauta y el macho que le responde. Estas pueden agruparse según diferentes categorías de pautas de conducta (sumisión y agresión). El objetivo fue describir la estructura de estas interacciones y analizar la frecuencia de las categorías observadas.Facultad de Ciencias Naturales y Muse

  • Comparación de pautas agonísticas entre juveniles y subadultos del elefante marino del sur (Mirounga leonina) de la isla 25 de Mayo, Antártida : ¿Desarrollo ontogenético o juego?
    2019
    Co-Authors: Ciai, Dante Nahuel, Pfoh Malena, Rossi, Juan B., Durante M., Ferrari, Héctor Ricardo, Belsito G., Negrete Javier
    Abstract:

    Las interacciones agonísticas entre machos de elefante marino (Mirounga leonina) son muy frecuentes. Sin embargo, se conoce poco sobre el desarrollo ontogenético de este comportamiento. Las interacciones observadas en machos inmaduros de la especie son, generalmente, consideradas como ’juego’, pero podrían representar aprendizaje o práctica de actos que serán realizados durante los combates en la etapa adulta. A fin de corroborar esto, comparamos las frecuencias de ocurrencia de pautas agonísticas realizadas por individuos juveniles y subadultos, presentes en un etograma parcial de agonismo previo de interacciones de machos adultos de la especie.Facultad de Ciencias Naturales y Muse

  • The feeding habits of the Southern elephant seal, Mirounga leonina, at Isla 25 de Mayo/King George Island, South Shetland Islands
    'Springer Science and Business Media LLC', 2015
    Co-Authors: Daneri, Gustavo Adolfo, Negrete Javier, Carlini A.r., Marschoff, Enrique Ricardo, Harrington Ana, Mennucci J.a., Márquez M. E.
    Abstract:

    The Southern elephant seal (Mirounga leonina) is a major consumer from the Southern Ocean. This species is highly sexually dimorphic and frequently exhibits resource partitioning according to sex and/or age classes. This study analysed the feeding habits of the M. leonina population from Isla 25 de mayo (King George Island) in the spring/summer seasons of 1995/1996–2002/2003. A total of 232 individuals from different sex-age groups were stomach lavaged. The analysis of stomach samples showed that cephalopods were the main prey followed by fish, their frequency of occurrence being 98.1 and 17.9 % respectively. Cephalopods were dominated by the Antarctic glacial squid, Psychroteuthis glacialis, which occurred in 83 % of samples, constituting 57.2 % in numbers and 61.3 % in mass. Octopods were of lesser relevance, occurring in 18 % of samples, but became more important in the diet of male individuals. Juvenile seals fed on a lower variety of cephalopod prey than older ones. This would coincide with the diving pattern characteristic of the different sex-age categories of seals. The predominance of P. glacialis might be associated with the more southerly location of the foraging areas of this population compared to others. Fish were largely represented by the myctophid Gymnoscopelus nicholsi, which occurred in 81.3 % of samples containing otoliths and constituted 76.4 % in numbers and 66.4 % in mass. However, while myctophids may be the dominant fish prey of elephant seals in areas close to the South Shetlands, they would be probably replaced by P. antarcticum as seals migrate towards higher latitudes.Fil: Daneri, Gustavo Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Carlini, A.R.. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Marschoff, Enrique Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Harrington, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; ArgentinaFil: Negrete, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Mennucci, J.A.. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Márquez, M. E. I.. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentin