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Movements of southern elephant seals (Mirounga leonina) from Davis Base, Antarctica: combining population genetics and tracking data. Polar Biol 2022. [DOI: 10.1007/s00300-022-03058-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
AbstractMarine animals such as the southern elephant seal (Mirounga leonina) rely on a productive marine environment and are vulnerable to oceanic changes that can affect their reproduction and survival rates. Davis Base, Antarctica, acts as a moulting site for southern elephant seals that forage in Prydz Bay, but the mitochondrial haplotype diversity and natal source populations of these seals have not been characterized. In this study, we combined genetic and animal tracking data on these moulting seals to identify levels of mitochondrial haplotype diversity, natal source population, and movement behaviours during foraging and haul-out periods. Using partial sequences of the mitochondrial control region, we identified two major breeding mitochondrial lineages of seals at Davis Base. We found that the majority of the seals originated from breeding stocks within the South Atlantic Ocean and South Indian Ocean. One seal was grouped with the Macquarie Island breeding stock (South Pacific Ocean). The Macquarie Island population, unlike the other two stocks, is decreasing in size. Tracking data revealed long-distance foraging activity of the Macquarie Island seal around Crozet Islands. We speculate that changes to the Antarctic marine environment can result in a shift in foraging and movement strategies, which subsequently affects seal population growth rates.
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Negrete J, Juáres M, Mennucci JA, Daneri G. Population status of southern elephant seals (Mirounga leonina) at Peninsula Potter breeding colony, Antarctica. Polar Biol 2022. [DOI: 10.1007/s00300-022-03044-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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3
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Elephant seals (Mirounga leonina) at Potter Peninsula, King George Island, Antarctica: genetic variation of the breeding colony and gene flow with other colonies. Polar Biol 2022. [DOI: 10.1007/s00300-021-02996-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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4
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Nichols HJ, Fuchs B, Paijmans AJ, Lewis G, Bonin CA, Goebel ME, Hoffman JI. Where are the beachmasters? Unexpectedly weak polygyny among southern elephant seals on a South Shetland Island. J Zool (1987) 2021. [DOI: 10.1111/jzo.12936] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- H. J. Nichols
- Department of Biosciences Swansea University Swansea UK
- Department of Animal Behaviour University of Bielefeld Bielefeld Germany
| | - B. Fuchs
- Department of Animal Behaviour University of Bielefeld Bielefeld Germany
| | - A. J. Paijmans
- Department of Animal Behaviour University of Bielefeld Bielefeld Germany
| | - G. Lewis
- Department of Biosciences Swansea University Swansea UK
| | - C. A. Bonin
- Department of Marine and Environmental Sciences Hampton University Hampton USA
| | - M. E. Goebel
- Institute of Marine Sciences University of California Santa Cruz Santa Cruz CA USA
| | - J. I. Hoffman
- Department of Animal Behaviour University of Bielefeld Bielefeld Germany
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5
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Volzke S, McMahon CR, Hindell MA, Burton HR, Wotherspoon SJ. Climate influences on female survival in a declining population of southern elephant seals ( Mirounga leonina). Ecol Evol 2021; 11:11333-11344. [PMID: 34429922 PMCID: PMC8366891 DOI: 10.1002/ece3.7919] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 06/21/2021] [Accepted: 06/25/2021] [Indexed: 11/22/2022] Open
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.
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Affiliation(s)
- Sophia Volzke
- Institute for Marine & Antarctic StudiesUniversity of TasmaniaHobartTas.Australia
| | - Clive R. McMahon
- Institute for Marine & Antarctic StudiesUniversity of TasmaniaHobartTas.Australia
- IMOS Animal TaggingSydney Institute of Marine ScienceMosmanNSWAustralia
| | - Mark A. Hindell
- Institute for Marine & Antarctic StudiesUniversity of TasmaniaHobartTas.Australia
- Antarctic Climate and Ecosystems Cooperative Research CentreUniversity of TasmaniaHobartTas.Australia
| | - Harry R. Burton
- Australian Antarctic DivisionDepartment of Agriculture, Water and the EnvironmentKingstonTas.Australia
| | - Simon J. Wotherspoon
- Institute for Marine & Antarctic StudiesUniversity of TasmaniaHobartTas.Australia
- Australian Antarctic DivisionDepartment of Agriculture, Water and the EnvironmentKingstonTas.Australia
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6
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Henderson AF, McMahon CR, Harcourt R, Guinet C, Picard B, Wotherspoon S, Hindell MA. Inferring Variation in Southern Elephant Seal At-Sea Mortality by Modelling Tag Failure. FRONTIERS IN MARINE SCIENCE 2020; 7. [PMID: 0 DOI: 10.3389/fmars.2020.517901] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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7
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Breeding Colony Dynamics of Southern Elephant Seals at Patelnia Point, King George Island, Antarctica. REMOTE SENSING 2020. [DOI: 10.3390/rs12182964] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
During the 2019 breeding season (October-December), a battery-powered DIJ Inspire 2 drone was used to investigate a breeding southern elephant seal colony located at Patelnia Point (ASPA 128, King George Island, South Shetland Islands, maritime Antarctica). Twelve unmanned aerial vehicle (UAV) missions conducted 50–70 m above ground level (AGL) were completed to monitor the breeding ground with a maximum of 0.348 km2. The missions were planned in Pix4D Capture software. A drone, with the support of ground cameras and observations, was used to derive population counts, map harems, and track the phenology of the southern elephant seals. Based on data obtained from the UAV missions, orthophotomaps were created in PIX4D Mapper and then analyzed in QGIS. Calculated values of body size parameters such as body length and orthogonal body surface area were used to determine the age and sex of individuals. Analysis of the ranges of the harems on particular days, supported by an analysis of land conditions that generate physical barriers to the movement of animals, allowed zones in which the transformations of groups of harems took place to be determined. The hypothesized hermeticity of the designated zones was supported by statistical tests. The use of drones allows for comprehensive population analyses of the breeding colonies of elephant seals such as censuses of pups and adult individuals, determination of the sex ratio, and spatial analysis of the distribution of breeding formations. In addition, it allows for a more accurate result than ground counting.
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8
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Valenzuela-Toro AM, Zicos MH, Pyenson ND. Extreme dispersal or human-transport? The enigmatic case of an extralimital freshwater occurrence of a Southern elephant seal from Indiana. PeerJ 2020; 8:e9665. [PMID: 32953258 PMCID: PMC7474520 DOI: 10.7717/peerj.9665] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 07/15/2020] [Indexed: 11/20/2022] Open
Abstract
Elephant seals (Mirounga spp.) are the largest living pinnipeds, and the spatial scales of their ecology, with dives over 1 km in depth and foraging trips over 10,000 km long, are unrivalled by their near relatives. Here we report the discovery of an incomplete Holocene age Southern elephant seal (M. leonina) rostrum from Indiana, USA. The surviving material are two casts of the original specimen, which was collected in a construction excavation close to the Wabash River near Lafayette, Indiana. The original specimen was mostly destroyed for radiometric dating analyses in the 1970s, which resulted in an age of 1,260 ± 90 years before the present. The existence of sediments in the original specimen suggests some type of post depositional fluvial transportation. The prevalent evidence suggests that this male Southern elephant seal crossed the equator and the Gulf of Mexico, and then entered the Mississippi River system, stranding far upriver in Indiana or adjacent areas, similar to other reported examples of lost marine mammals in freshwater systems. Based on potential cut marks, we cannot exclude human-mediated transportation or scavenging by Indigenous peoples as a contributing factor of this occurrence. The material reported here represents by far the northernmost occurrence of a Southern elephant seal in the Northern Hemisphere ever recorded. The unusual occurrence of a top marine predator >1,000 km from the closest marine effluent as a potential extreme case of dispersal emphasizes how marine invasions of freshwater systems have happened frequently through historical (and likely geological) time.
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Affiliation(s)
- Ana M Valenzuela-Toro
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, United States of America.,Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, United States of America
| | - Maria H Zicos
- School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom.,Department of Earth Sciences, Natural History Museum, London, United Kingdom
| | - Nicholas D Pyenson
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, United States of America.,Department of Paleontology and Geology, Burke Museum of Natural History and Culture, Seattle, WA, United States of America
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9
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Mestre J, Authier M, Cherel Y, Harcourt R, McMahon CR, Hindell MA, Charrassin JB, Guinet C. Decadal changes in blood δ 13C values, at-sea distribution, and weaning mass of southern elephant seals from Kerguelen Islands. Proc Biol Sci 2020; 287:20201544. [PMID: 32811318 PMCID: PMC7482287 DOI: 10.1098/rspb.2020.1544] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 07/27/2020] [Indexed: 11/12/2022] Open
Abstract
Changes in the foraging environment and at-sea distribution of southern elephant seals from Kerguelen Islands were investigated over a decade (2004-2018) using tracking, weaning mass, and blood δ13C values. Females showed either a sub-Antarctic or an Antarctic foraging strategy, and no significant shift in their at-sea distribution was detected between 2004 and 2017. The proportion of females foraging in sub-Antarctic versus Antarctic habitats did not change over the 2006-2018 period. Pup weaning mass varied according to the foraging habitat of their mothers. The weaning mass of sub-Antarctic foraging mothers' pups decreased by 11.7 kg over the study period, but they were on average 5.8 kg heavier than pups from Antarctic foraging mothers. Pup blood δ13C values decreased by 1.1‰ over the study period regardless of their sex and the presumed foraging habitat of their mothers. Together, these results suggest an ecological change is occurring within the Indian sector of the Southern Ocean with possible consequences on the foraging performance of southern elephant seals. We hypothesize that this shift in δ13C is related to a change in primary production and/or in the composition of phytoplankton communities, but this requires further multidisciplinary investigations.
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Affiliation(s)
- Julie Mestre
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 du CNRS-La Rochelle Université, 79360 Villiers-en-Bois, France
- Sorbonne Université, Collège Doctoral, F-75005 Paris, France
| | - Matthieu Authier
- Observatoire PELAGIS, UMS 3462 La Rochelle Université and CNRS, La Rochelle, France
- ADERA, Pessac Cedex, France
| | - Yves Cherel
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 du CNRS-La Rochelle Université, 79360 Villiers-en-Bois, France
| | - Rob Harcourt
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Clive R. McMahon
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, Australia
- IMOS Animal Tagging, Sydney Institute of Marine Science, Sydney, NSW, Australia
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | - Mark A. Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS, Australia
| | | | - Christophe Guinet
- Centre d'Etudes Biologiques de Chizé (CEBC), UMR 7372 du CNRS-La Rochelle Université, 79360 Villiers-en-Bois, France
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10
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Lloyd KJ, Oosthuizen WC, Bester MN, de Bruyn PJN. Trade-offs between age-related breeding improvement and survival senescence in highly polygynous elephant seals: Dominant males always do better. J Anim Ecol 2019; 89:897-909. [PMID: 31746466 DOI: 10.1111/1365-2656.13145] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 10/02/2019] [Indexed: 11/27/2022]
Abstract
Life history trade-off theory predicts that current reproduction can negatively affect survival and future reproduction. Few studies have assessed breeding costs for males of polygynous species compared to females, despite substantial variation in breeding success among individual males (e.g. subordinate cf. dominant breeders). Specifically, differentiating between the cost of attending breeding seasons, and the additional cost of successfully securing and mating females is lacking. We investigated whether trade-offs are present in the highly polygynous male southern elephant seal (Mirounga leonina) using 34-years of individual-level data. We compare age-specific survival, recruitment and future breeding success probabilities of pre-breeders (males yet to recruit) and breeders (subordinate and dominant social ranks) using multievent models. Pre-breeders and breeders of overlapping ages had similar survival probabilities, suggesting that there was no attendance cost for early recruits. In addition, the probability of recruiting as a dominant breeder never exceeded recruitment probability as a subordinate breeder of the same age. Therefore, older pre-breeders that delayed attendance costs generally did not improve their breeding success (probability of being dominant) at recruitment more than younger recruits. Rather, recruitment age may be a function of individual quality, with lower quality individuals requiring more time to socially mature. When comparing subordinate and dominant breeders, we found clear evidence for survival senescence, with subordinate breeders having a higher baseline mortality. In contrast, age-specific future breeding success (probability of being dominant at t + 1) increased with age, with dominant breeders maintaining higher subsequent breeding success than subordinate breeders. The opposite trends in survival and future breeding success for both subordinate and dominant breeders may indicate a lifetime, population-level trade-off. However, we found no evidence to suggest that being a dominant breeder consecutively (and having a higher accumulated breeding cost) accelerated the rate of senescence when compared to individuals that were previously subordinate. Thus, males experienced actuarial senescence regardless of social rank, with dominant (and possibly high quality) breeders showing a reduced trade-off between survival and future breeding success. We make several novel contributions to understanding polygynous male life histories and southern elephant seal demography.
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Affiliation(s)
- Kyle J Lloyd
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, Pretoria, 0028, South Africa
| | - W Chris Oosthuizen
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, Pretoria, 0028, South Africa
| | - Marthán N Bester
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, Pretoria, 0028, South Africa
| | - P J Nico de Bruyn
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, Pretoria, 0028, South Africa
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11
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Oosthuizen WC, Postma M, Altwegg R, Nevoux M, Pradel R, Bester MN, Bruyn PJN. Individual heterogeneity in life‐history trade‐offs with age at first reproduction in capital breeding elephant seals. POPUL ECOL 2019. [DOI: 10.1002/1438-390x.12015] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- W. Chris Oosthuizen
- Mammal Research Institute, Department of Zoology and Entomology University of Pretoria Hatfield South Africa
| | - Martin Postma
- Mammal Research Institute, Department of Zoology and Entomology University of Pretoria Hatfield South Africa
| | - Res Altwegg
- Centre for Statistics in Ecology Environment and Conservation, Department of Statistical Sciences University of Cape Town Rondebosch South Africa
- African Climate and Development Initiative, University of Cape Town Rondebosch South Africa
| | - Marie Nevoux
- Mammal Research Institute, Department of Zoology and Entomology University of Pretoria Hatfield South Africa
- UMRESE, Ecology and Ecosystem Health, Agrocampus Ouest, INRA Rennes France
| | - Roger Pradel
- Biostatistics and Population Biology Group, CEFE, CNRS, University of Montpellier Montpellier France
| | - Marthán N. Bester
- Mammal Research Institute, Department of Zoology and Entomology University of Pretoria Hatfield South Africa
| | - P. J. Nico Bruyn
- Mammal Research Institute, Department of Zoology and Entomology University of Pretoria Hatfield South Africa
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12
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A quantitative, hierarchical approach for detecting drift dives and tracking buoyancy changes in southern elephant seals. Sci Rep 2019; 9:8936. [PMID: 31222003 PMCID: PMC6586652 DOI: 10.1038/s41598-019-44970-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 05/29/2019] [Indexed: 11/08/2022] Open
Abstract
Foraging behaviour of marine predators inferred from the analysis of horizontal or vertical movements commonly lack quantitative information about foraging success. Several marine mammal species are known to perform dives where they passively drift in the water column, termed “drift” dives. The drift rate is determined by the animal’s buoyancy, which can be used to make inference regarding body condition. Long term dive records retrieved via satellite uplink are often summarized before transmission. This loss of resolution hampers identification of drift dives. Here, we develop a flexible, hierarchically structured approach to identify drift dives and estimate the drift rate from the summarized time-depth profiles that are increasingly available to the global research community. Based on high-resolution dive data from southern elephant seals, we classify dives as drift/non-drift and apply a summarization algorithm. We then (i) automatically generate dive groups based on inflection point ordering using a ‘Reverse’ Broken-Stick Algorithm, (ii) develop a set of threshold criteria to apply across groups, ensuring non-drift dives are most efficiently rejected, and (iii) finally implement a custom Kalman filter to retain the remaining dives that are within the seals estimated drifting time series. Validation with independent data sets shows our method retains approximately 3% of all dives, of which 88% are true drift dives. The drift rate estimates are unbiased, with the upper 95% quantile of the mean squared error between the daily averaged summarized profiles using our method (SDDR) and the observed daily averaged drift rate (ODDR) being only 0.0015. The trend of the drifting time-series match expectations for capital breeders, showing the lowest body condition commencing foraging trips and a progressive improvement as they remain at sea. Our method offers sufficient resolution to track small changes in body condition at a fine temporal scale. This approach overcomes a long-term challenge for large existing and ongoing data collections, with potential application across other drift diving species. Enabling robust identification of foraging success at sea offers a rare and valuable opportunity for monitoring marine ecosystem productivity in space and time by tracking the success of a top predator.
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Cárcamo D, Pizarro M, Orellana M, Muñoz L, Pavez G, Sepúlveda M, Durán LR, Oliva D. Are southern elephant seals re-invading mid-latitude grounds? New sightings and first birth records off the Chilean Coast. Polar Biol 2018. [DOI: 10.1007/s00300-018-2433-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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14
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Aspects of the ecology of killer whale (Orcinus orca Linn.) groups in the near-shore waters of Sub-Antarctic Macquarie Island. Polar Biol 2018. [DOI: 10.1007/s00300-018-2361-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Goedegebuure M, Melbourne-Thomas J, Corney SP, McMahon CR, Hindell MA. Modelling southern elephant seals Mirounga leonina using an individual-based model coupled with a dynamic energy budget. PLoS One 2018; 13:e0194950. [PMID: 29596456 PMCID: PMC5875804 DOI: 10.1371/journal.pone.0194950] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 03/13/2018] [Indexed: 01/08/2023] Open
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.
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Affiliation(s)
- Merel Goedegebuure
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7000 Australia
- Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7000 Australia
| | - Jessica Melbourne-Thomas
- Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7000 Australia
- Australian Antarctic Division, Channel Highway, Kingston Tasmania 7050 Australia
| | - Stuart P. Corney
- Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7000 Australia
| | - Clive R. McMahon
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7000 Australia
- Sydney Institute of Marine Science, 19 Chowder Bay Road, Mosman, New South Wales 2088, Australia
| | - Mark A. Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7000 Australia
- Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7000 Australia
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16
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Hindell MA, Sumner M, Bestley S, Wotherspoon S, Harcourt RG, Lea MA, Alderman R, McMahon CR. Decadal changes in habitat characteristics influence population trajectories of southern elephant seals. GLOBAL CHANGE BIOLOGY 2017; 23:5136-5150. [PMID: 28590592 DOI: 10.1111/gcb.13776] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 04/30/2017] [Indexed: 06/07/2023]
Abstract
Understanding divergent biological responses to climate change is important for predicting ecosystem level consequences. We use species habitat models to predict the winter foraging habitats of female southern elephant seals and investigate how changes in environmental variables within these habitats may be related to observed decreases in the Macquarie Island population. There were three main groups of seals that specialized in different ocean realms (the sub-Antarctic, the Ross Sea and the Victoria Land Coast). The physical and climate attributes (e.g. wind strength, sea surface height, ocean current strength) varied amongst the realms and also displayed different temporal trends over the last two to four decades. Most notably, sea ice extent increased on average in the Victoria Land realm while it decreased overall in the Ross Sea realm. Using a species distribution model relating mean residence times (time spent in each 50 × 50 km grid cell) to 9 climate and physical co-variates, we developed spatial predictions of residence time to identify the core regions used by the seals across the Southern Ocean from 120°E to 120°W. Population size at Macquarie Island was negatively correlated with ice concentration within the core habitat of seals using the Victoria Land Coast and the Ross Sea. Sea ice extent and concentration is predicted to continue to change in the Southern Ocean, having unknown consequences for the biota of the region. The proportion of Macquarie Island females (40%) utilizing the relatively stable sub-Antarctic region, may buffer this population against longer-term regional changes in habitat quality, but the Macquarie Island population has persistently decreased (-1.45% per annum) over seven decades indicating that environmental changes in the Antarctic are acting on the remaining 60% of the population to impose a long-term population decline in a top Southern Ocean predator.
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Affiliation(s)
- Mark A Hindell
- Institute for Marine & Antarctic Studies, Hobart, Australia
- Antarctic Climate and Ecosystems CRC, University of Tasmania, Hobart, Australia
| | - Michael Sumner
- Antarctic Climate and Ecosystems CRC, University of Tasmania, Hobart, Australia
- Australian Antarctic Division, Kingston, Australia
| | - Sophie Bestley
- Institute for Marine & Antarctic Studies, Hobart, Australia
- Australian Antarctic Division, Kingston, Australia
| | - Simon Wotherspoon
- Institute for Marine & Antarctic Studies, Hobart, Australia
- Australian Antarctic Division, Kingston, Australia
| | - Robert G Harcourt
- Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, Australia
| | - Mary-Anne Lea
- Institute for Marine & Antarctic Studies, Hobart, Australia
| | - Rachael Alderman
- Department of Primary Industries, Parks, Water and Environment, Hobart, Australia
| | - Clive R McMahon
- Institute for Marine & Antarctic Studies, Hobart, Australia
- Sydney Institute of Marine Science, Mosman, Australia
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18
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Abadía-Cardoso A, Freimer NB, Deiner K, Garza JC. Molecular Population Genetics of the Northern Elephant Seal Mirounga angustirostris. J Hered 2017; 108:618-627. [PMID: 28821186 PMCID: PMC5892393 DOI: 10.1093/jhered/esx053] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Accepted: 06/21/2017] [Indexed: 11/13/2022] Open
Abstract
The northern elephant seal, Mirounga angustirostris, was heavily hunted and declared extinct in the 19th century. However, a colony remained on remote Guadalupe Island, Mexico and the species has since repopulated most of its historical distribution. Here, we present a comprehensive evaluation of genetic variation in the species. First, we assess the effect of the demographic bottleneck on microsatellite variability and compare it with that found in other pinnipeds, demonstrating levels of variation similar to that in species that continue to be threatened with extinction. Next, we use sequence data from these markers to demonstrate that some of the limited polymorphism predates the bottleneck. However, most contemporary variation appears to have arisen recently and persisted due to exponential growth. We also describe how we use the range in allele size of microsatellites to estimate ancestral effective population size before the bottleneck, demonstrating a large reduction in effective size. We then employ a classical method for bacteria to estimate the microsatellite mutation rate in the species, deriving an estimate that is extremely similar to that estimated for a similar set of loci in humans, indicating consistency of microsatellite mutation rates in mammals. Finally, we find slight significant structure between some geographically separated colonies, although its biological significance is unclear. This work demonstrates that genetic analysis can be useful for evaluating the population biology of the northern elephant seal, in spite of the bottleneck that removed most genetic variation from the species.
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Affiliation(s)
- Alicia Abadía-Cardoso
- Facultad de Ciencias Marinas, Universidad Autónoma de Baja California, Carretera Tijuana-Ensenada Km 103, Pedregal Playitas, 22860 Ensenada, BC, Mexico; University of California, Santa Cruz, 110 McAllister Way, Santa Cruz, CA 95060; Southwest Fisheries Science Center, National Marine Fisheries Service, 110 McAllister Way, Santa Cruz, CA 95060; Center for Neurobehavioral Genetics, University of California, Los Angeles, 695 Charles E. Young Drive South, Los Angeles, CA 90095. Department of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd., Ithaca, NY 14850
| | - Nelson B Freimer
- Facultad de Ciencias Marinas, Universidad Autónoma de Baja California, Carretera Tijuana-Ensenada Km 103, Pedregal Playitas, 22860 Ensenada, BC, Mexico; University of California, Santa Cruz, 110 McAllister Way, Santa Cruz, CA 95060; Southwest Fisheries Science Center, National Marine Fisheries Service, 110 McAllister Way, Santa Cruz, CA 95060; Center for Neurobehavioral Genetics, University of California, Los Angeles, 695 Charles E. Young Drive South, Los Angeles, CA 90095. Department of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd., Ithaca, NY 14850
| | - Kristy Deiner
- Facultad de Ciencias Marinas, Universidad Autónoma de Baja California, Carretera Tijuana-Ensenada Km 103, Pedregal Playitas, 22860 Ensenada, BC, Mexico; University of California, Santa Cruz, 110 McAllister Way, Santa Cruz, CA 95060; Southwest Fisheries Science Center, National Marine Fisheries Service, 110 McAllister Way, Santa Cruz, CA 95060; Center for Neurobehavioral Genetics, University of California, Los Angeles, 695 Charles E. Young Drive South, Los Angeles, CA 90095. Department of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd., Ithaca, NY 14850
| | - John Carlos Garza
- Facultad de Ciencias Marinas, Universidad Autónoma de Baja California, Carretera Tijuana-Ensenada Km 103, Pedregal Playitas, 22860 Ensenada, BC, Mexico; University of California, Santa Cruz, 110 McAllister Way, Santa Cruz, CA 95060; Southwest Fisheries Science Center, National Marine Fisheries Service, 110 McAllister Way, Santa Cruz, CA 95060; Center for Neurobehavioral Genetics, University of California, Los Angeles, 695 Charles E. Young Drive South, Los Angeles, CA 90095. Department of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd., Ithaca, NY 14850
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Clausius E, McMahon CR, Hindell MA. 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; 12:e0173427. [PMID: 28301546 PMCID: PMC5354283 DOI: 10.1371/journal.pone.0173427] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 02/19/2017] [Indexed: 01/31/2023] Open
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.
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Affiliation(s)
- Ella Clausius
- Centre for Ecology and Biodiversity, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | - Clive R. McMahon
- Sydney Institute of Marine Science, Mosman, New South Wales, Australia
| | - Mark A. Hindell
- Centre for Ecology and Biodiversity, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
- Antarctic Climate and Ecosystems CRC, University of Tasmania, Hobart, Tasmania, Australia
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20
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van den Hoff J, Kilpatrick R, Welsford D. Southern elephant seals (Mirounga leonina Linn.) depredate toothfish longlines in the midnight zone. PLoS One 2017; 12:e0172396. [PMID: 28234988 PMCID: PMC5325274 DOI: 10.1371/journal.pone.0172396] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 02/03/2017] [Indexed: 11/19/2022] Open
Abstract
Humans have devised fishing technologies that compete with marine predators for fish resources world-wide. One such fishery for the Patagonian toothfish (Dissostichus eleginoides) has developed interactions with a range of predators, some of which are marine mammals capable of diving to extreme depths for extended periods. A deep-sea camera system deployed within a toothfish fishery operating in the Southern Ocean acquired the first-ever video footage of an extreme-diver, the southern elephant seal (Mirounga leonina), depredating catch from longlines set at depths in excess of 1000m. The interactions recorded were non-lethal, however independent fisheries observer reports confirm elephant seal-longline interactions can be lethal. The seals behaviour of depredating catch at depth during the line soak-period differs to other surface-breathing species and thus presents a unique challenge to mitigate their by-catch. Deployments of deep-sea cameras on exploratory fishing gear prior to licencing and permit approvals would gather valuable information regarding the nature of interactions between deep diving/dwelling marine species and longline fisheries operating at bathypelagic depths. Furthermore, the positive identification by sex and age class of species interacting with commercial fisheries would assist in formulating management plans and mitigation strategies founded on species-specific life-history strategies.
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Affiliation(s)
- John van den Hoff
- Australian Antarctic Division, Kingston, Tasmania, Australia
- * E-mail:
| | | | - Dirk Welsford
- Australian Antarctic Division, Kingston, Tasmania, Australia
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21
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McMahon CR, Thums M, Bradshaw M, Busby S, Chapple V, Evans M, Goodlich S, Holland C, Raudino H, Rebuck P, Hindell MA. It’s a girl! A female southern elephant seal born in Western Australia. AUST J ZOOL 2017. [DOI: 10.1071/zo17036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Southern elephant seals typically breed on subantarctic islands and breeding in more temperate regions is rare. This small female (~1.42 m) that weaned after 25 days is smaller than the average weaned female elephant seal and her survival prospects are correspondingly low (20–35%). The fact that the elephant seal was successfully weaned offers some insight into the breeding plasticity in this species.
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22
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Corrigan LJ, Fabiani A, Chauke LF, McMahon CR, Bruyn M, Bester MN, Bastos A, Campagna C, Muelbert MMC, Hoelzel AR. Population differentiation in the context of Holocene climate change for a migratory marine species, the southern elephant seal. J Evol Biol 2016; 29:1667-79. [PMID: 27012933 DOI: 10.1111/jeb.12870] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 03/03/2016] [Accepted: 03/22/2016] [Indexed: 11/30/2022]
Affiliation(s)
- L. J. Corrigan
- School of Biological and Biomedical Sciences Durham University Durham UK
| | - A. Fabiani
- School of Biological and Biomedical Sciences Durham University Durham UK
- Dipartimento di Biologia Università degli Studi di Roma Tor Vergata Roma Italy
- Elephant Seal Research Group Sea Lion Island Falkland Islands
| | - L. F. Chauke
- School of Biological and Biomedical Sciences Durham University Durham UK
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Pretoria South Africa
| | - C. R. McMahon
- Sydney Institute of Marine Science Mosman NSW Australia
| | - M. Bruyn
- School of Biological and Biomedical Sciences Durham University Durham UK
| | - M. N. Bester
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Pretoria South Africa
| | - A. Bastos
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Pretoria South Africa
| | - C. Campagna
- Marine Program Wildlife Conservation Soc Buenos Aires Argentina
| | - M. M. C. Muelbert
- Instituto de Oceanografia Universidade Federal do Rio Grande Rio Grande Brasil
| | - A. R. Hoelzel
- School of Biological and Biomedical Sciences Durham University Durham UK
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23
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Hindell MA, McMahon CR, Bester MN, Boehme L, Costa D, Fedak MA, Guinet C, Herraiz‐Borreguero L, Harcourt RG, Huckstadt L, Kovacs KM, Lydersen C, McIntyre T, Muelbert M, Patterson T, Roquet F, Williams G, Charrassin J. Circumpolar habitat use in the southern elephant seal: implications for foraging success and population trajectories. Ecosphere 2016. [DOI: 10.1002/ecs2.1213] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Mark A. Hindell
- Institute for Marine and Antarctic Studies University of Tasmania Hobart Tasmania 7001 Australia
- Antarctic Climate & Ecosystem Cooperative Research Centre University of Tasmania Hobart Tasmania 7001 Australia
| | - Clive R. McMahon
- Institute for Marine and Antarctic Studies University of Tasmania Hobart Tasmania 7001 Australia
- Sydney Institute of Marine Science 19 Chowder Bay Road Mosman New South Wales 2088 Australia
| | - Marthán N. Bester
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Private Bag X20 Hatfield 0028 South Africa
| | - Lars Boehme
- Sea Mammal Research Unit Scottish Oceans Institute University of St Andrews St Andrews UK
| | - Daniel Costa
- Department of Ecology and Evolutionary Biology University of California Santa Cruz California USA
| | - Mike A. Fedak
- Sea Mammal Research Unit Scottish Oceans Institute University of St Andrews St Andrews UK
| | - Christophe Guinet
- Centre d'Etudes Biologiques de Chizé Centre National de la Recherche Scientifique Villiers en Bois France
| | - Laura Herraiz‐Borreguero
- Antarctic Climate & Ecosystem Cooperative Research Centre University of Tasmania Hobart Tasmania 7001 Australia
- Centre for Ice and Climate Niels Bohr Institute University of Copenhagen Copenhagen Denmark
| | - Robert G. Harcourt
- Department of Biological Sciences Macquarie University Sydney New South Wales 2109 Australia
| | - Luis Huckstadt
- Department of Ecology and Evolutionary Biology University of California Santa Cruz California USA
| | - Kit M. Kovacs
- Norwegian Polar Institute Fram Centre Tromsø N‐9296 Norway
| | | | - Trevor McIntyre
- Department of Zoology and Entomology Mammal Research Institute University of Pretoria Private Bag X20 Hatfield 0028 South Africa
| | - Monica Muelbert
- Instituto de Oceanografia Universidade Federal do Rio Grande Porto Alegre Brazil
| | - Toby Patterson
- CSIRO Wealth from Oceans Research Flagship and Marine & Atmospheric Research GPO Box 1538 Hobart Tasmania 7001 Australia
| | - Fabien Roquet
- Department of Meteorology Stockholm University Stockholm Sweden
| | - Guy Williams
- Antarctic Climate & Ecosystem Cooperative Research Centre University of Tasmania Hobart Tasmania 7001 Australia
| | - Jean‐Benoit Charrassin
- Laboratoire d'Océanographie et du Climat: Expérimentation et Approches Numériques Paris France
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24
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Cummings CR, Lea MA, Morrice MG, Wotherspoon S, Hindell MA. New insights into the cardiorespiratory physiology of weaned southern elephant seals (Mirounga leonina). CONSERVATION PHYSIOLOGY 2015; 3:cov049. [PMID: 27293733 PMCID: PMC4778465 DOI: 10.1093/conphys/cov049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 09/29/2015] [Accepted: 10/07/2015] [Indexed: 06/06/2023]
Abstract
Southern elephant seal (Mirounga leonina) pups must strike a balance between conserving energy during their post-weaning fast and simultaneously developing diving abilities to attain nutritional independence. Little is known about environmental influences on cardiorespiratory patterns, hence energy use, throughout the 6 week fast. Continuous heart rates were recorded for free-ranging, newly weaned southern elephant seals using heart rate time-depth recorders for 5-9 days at Sub-Antarctic Macquarie Island, during October 1994 (n = 1), 1995 (n = 4) and 1996 (n = 1). Daytime observations of respiration and behaviour were made throughout. We present the first instance of synchronous heart rate traces recorded simultaneously for individual weaners. Generalized additive models revealed that a sinusoidal pattern of diurnal heart rate elevation and nocturnal depression was evident in all seals and, on at least one occasion, a conspicuous break in this pattern coincided with an extreme cold weather event. Seals in this study were capable of considerable cardiorespiratory control and regularly demonstrated bradycardia during periods of resting apnoea. Apnoeic duration ranged from 33 to 291 s (mean 134 s). Apnoeic heart rates (mean 67 ± 15 beats min(-1), range 40-114 beats min(-1)) were on average 19.7% lower than those exhibited during periods of eupnoea (mean 83 ± 15 beats min(-1), range 44-124 beats min(-1)). The early development of the cardiorespiratory response is characterized by arrhythmic heart and respiration rates. The strong temporal patterns observed are being driven by the opposing requirements of maximizing time spent fasting in order to develop diving capabilities and of maximizing departure mass. This pilot study has highlighted a potentially large effect of ambient weather conditions on newly weaned southern elephant seal cardiorespiratory activity. Given the increasing westerlies and more erratic and increasing storminess associated with the Southern Annular Mode predicted in the Southern Ocean, the patterns observed here warrant further investigation.
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Affiliation(s)
- Cloe R Cummings
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7004, Australia
| | - Mary-Anne Lea
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7004, Australia
| | - Margaret G Morrice
- School of Life and Environmental Sciences, Deakin University, Warrnambool, VIC 3280, Australia
| | - Simon Wotherspoon
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7004, Australia
| | - Mark A Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7004, Australia
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26
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McMahon CR, New LF, Fairley EJ, Hindell MA, Burton HR. The effects of body size and climate on post‐weaning survival of elephant seals at
H
eard
I
sland. J Zool (1987) 2015. [DOI: 10.1111/jzo.12279] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- C. R. McMahon
- Sydney Institute of Marine Science Mosman NSW Australia
- Australian Antarctic Division Hobart Tas. Australia
| | - L. F. New
- US Marine Mammal Commission Bethesda MD USA
- USGS Patuxent Wildlife Research Center Laurel MD USA
- Washington State University Vancouver WA USA
| | | | - M. A. Hindell
- Institute for Marine and Antarctic Studies University of Tasmania Hobart Tas. Australia
| | - H. R. Burton
- Australian Antarctic Division Hobart Tas. Australia
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27
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Oosthuizen WC, Bester MN, Altwegg R, McIntyre T, de Bruyn PJN. Decomposing the variance in southern elephant seal weaning mass: partitioning environmental signals and maternal effects. Ecosphere 2015. [DOI: 10.1890/es14-00508.1] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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28
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Loza CM, Scarano AC, Soibelzon LH, Negrete J, Carlini AA. Morphology of the tympanic-basicranial region in Mirounga leonina (Phocidae, Carnivora), postnatal ontogeny and sexual dimorphism. J Anat 2015; 226:354-72. [PMID: 25827162 DOI: 10.1111/joa.12286] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2015] [Indexed: 11/28/2022] Open
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.
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Affiliation(s)
- C M Loza
- División Paleontología de Vertebrados, Museo de La Plata, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Argentina
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Spitz J, Becquet V, Rosen DAS, Trites AW. A nutrigenomic approach to detect nutritional stress from gene expression in blood samples drawn from Steller sea lions. Comp Biochem Physiol A Mol Integr Physiol 2015; 187:214-23. [PMID: 25700740 DOI: 10.1016/j.cbpa.2015.02.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 02/04/2015] [Accepted: 02/08/2015] [Indexed: 02/07/2023]
Abstract
Gene expression profiles are increasingly being used as biomarkers to detect the physiological responses of a number of species to disease, nutrition, and other stressors. However, little attention has been given to using gene expression to assess the stressors and physiological status of marine mammals. We sought to develop and validate a nutrigenomic approach to quantify nutritional stress in Steller sea lions (Eumetopias jubatus). We subjected 4 female Steller sea lions to 3 feeding regimes over 70-day trials (unrestricted food intake, acute nutritional stress, and chronic nutritional stress), and drew blood samples from each animal at the end of each feeding regime. We then extracted the RNA of white blood cells and measured the response of 8 genes known to react to diet restriction in terrestrial mammals. Overall, we found that the genomic response of Steller sea lions experiencing nutritional stress was consistent with how terrestrial mammals respond to dietary restrictions. Our nutritionally stressed sea lions down-regulated some cellular processes involved in immune response and oxidative stress, and up-regulated pro-inflammatory responses and metabolic processes. Nutrigenomics appears to be a promising means to monitor nutritional status and contribute to mitigation measures needed to assist in the recovery of Steller sea lions and other at-risk species of marine mammals.
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Affiliation(s)
- Jérôme Spitz
- Marine Mammal Research Unit, Fisheries Centre, University of British Columbia, 2202 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada.
| | - Vanessa Becquet
- Littoral Environnement et Sociétés, UMR 7266 Université de La Rochelle/CNRS, 2 rue Olympe de Gouges, 17042 La Rochelle, Cedex, France
| | - David A S Rosen
- Marine Mammal Research Unit, Fisheries Centre, University of British Columbia, 2202 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Andrew W Trites
- Marine Mammal Research Unit, Fisheries Centre, University of British Columbia, 2202 Main Mall, Vancouver, British Columbia V6T 1Z4, Canada
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30
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Gürtler RE, Cohen JE. Invasive axis deer and wild boar in a protected area in Argentina, controlled hunting, and Taylor. WILDLIFE RESEARCH 2015. [DOI: 10.1071/wr20119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Desprez M, Harcourt R, Hindell MA, Cubaynes S, Gimenez O, McMahon CR. Age-specific cost of first reproduction in female southern elephant seals. Biol Lett 2014; 10:20140264. [PMID: 24872464 DOI: 10.1098/rsbl.2014.0264] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
When to commence breeding is a crucial life-history decision that may be the most important determinant of an individual's lifetime reproductive output and can have major consequences on population dynamics. The age at which individuals first reproduce is an important factor influencing the intensity of potential costs (e.g. reduced survival) involved in the first breeding event. However, quantifying age-related variation in the cost of first reproduction in wild animals remains challenging because of the difficulty in reliably recording the first breeding event. Here, using a multi-event capture-recapture model that accounts for both imperfect detection and uncertainty in the breeding status on an 18-year dataset involving 6637 individuals, we estimated age and state-specific survival of female elephant seals (Mirounga leonina) in the declining Macquarie Island population. We detected a clear cost of first reproduction on survival. This cost was higher for both younger first-time breeders and older first-time breeders compared with females recruiting at age four, the overall mean age at first reproduction. Neither earlier primiparity nor delaying primiparity appear to confer any evolutionary advantage, rather the optimal strategy seems to be to start breeding at a single age, 4 years.
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Affiliation(s)
- Marine Desprez
- Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia
| | - Robert Harcourt
- Marine Predator Research Group, Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia
| | - Mark A Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Sarah Cubaynes
- Department of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK
| | - Olivier Gimenez
- Centre d'Ecologie Fonctionnelle et Evolutive, Campus CNRS, UMR 5175, 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - Clive R McMahon
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia Sydney Institute of Marine Science, 19 Chowder Bay Road, Mosman, New South Wales 2088, Australia
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The feeding habits of the Southern elephant seal, Mirounga leonina, at Isla 25 de Mayo/King George Island, South Shetland Islands. Polar Biol 2014. [DOI: 10.1007/s00300-014-1629-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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McMahon CR, Howe H, van den Hoff J, Alderman R, Brolsma H, Hindell MA. Satellites, the all-seeing eyes in the sky: counting elephant seals from space. PLoS One 2014; 9:e92613. [PMID: 24651378 PMCID: PMC3961415 DOI: 10.1371/journal.pone.0092613] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 02/24/2014] [Indexed: 11/18/2022] Open
Abstract
Regular censuses are fundamental for the management of animal populations but, are logistically challenging for species living in remote regions. The advent of readily accessible, high resolution satellite images of earth mean that it is possible to resolve relatively small (0.6 m) objects, sufficient to discern large animals. To illustrate how these advances can be used to count animals in remote regions, individual elephant seals (Mirounga leonina) were counted using satellite imagery. We used an image taken on 10/10/2011 to count elephant seals (n = 1790 ± 306 (95%CL)) on the isthmus of Macquarie Island, an estimate which overlapped with concurrent ground counts (n = 1991). The number of individuals per harem estimated using the two approaches were highly correlated, with a slope close to one and the estimated intercept also encompassing zero. This proof of concept opens the way for satellites to be used as a standard censusing technique for inaccessible and cryptically coloured species. Quantifying the population trends of higher order predators provides an especially informative and tractable indicator of ecosystem health.
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Affiliation(s)
- Clive R. McMahon
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
- * E-mail:
| | - Hamish Howe
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
| | - John van den Hoff
- Australian Antarctic Division, Channel Highway, Kingston, Tasmania, Australia
| | - Rachael Alderman
- Threatened Species & Marine Section, Department of Primary Industries, Water and the Environment, Hobart, Tasmania, Australia
| | - Henk Brolsma
- Australian Antarctic Division, Channel Highway, Kingston, Tasmania, Australia
| | - Mark A. Hindell
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia
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van den Hoff J, McMahon CR, Simpkins GR, Hindell MA, Alderman R, Burton HR. Bottom-up regulation of a pole-ward migratory predator population. Proc Biol Sci 2014; 281:20132842. [PMID: 24619437 DOI: 10.1098/rspb.2013.2842] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
As the effects of regional climate change are most pronounced at polar latitudes, we might expect polar-ward migratory populations to respond as habitat suitability changes. The southern elephant seal (Mirounga leonina L.) is a pole-ward migratory species whose populations have mostly stabilized or increased in the past decade, the one exception being the Macquarie Island population which has decreased continuously over the past 50 years. To explore probable causes of this anomalous trend, we counted breeding female seals annually between 1988 and 2011 in order to relate annual rates of population change (r) to foraging habitat changes that have known connections with atmospheric variability. We found r (i) varied annually from -0.016 to 0.021 over the study period, (ii) was most effected by anomalous atmospheric variability after a 3 year time lag was introduced (R = 0.51) and (iii) was associated with sea-ice duration (SID) within the seals' foraging range at the same temporal lag. Negative r years may be extrapolated to explain, at least partially, the overall trend in seal abundance at Macquarie Island; specifically, increasing SID within the seals foraging range has a negative influence on their abundance at the island. Evidence is accruing that suggests southern elephant seal populations may respond positively to a reduced sea-ice field.
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Affiliation(s)
- John van den Hoff
- Australian Antarctic Division, , 203 Channel Highway, Kingston, Tasmania 7050, Australia, Institute for Marine and Antarctic Studies, University of Tasmania, , Hobart, Tasmania 7001, Australia, Climate Change Research Centre, University of New South Wales, , Sydney, New South Wales 2052, Australia, Department of Primary Industries, Parks, Water and Environment, , 134 Macquarie Street, Hobart, Tasmania 7000, Australia
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Walters A, Lea MA, van den Hoff J, Field IC, Virtue P, Sokolov S, Pinkerton MH, Hindell MA. Spatially explicit estimates of prey consumption reveal a new krill predator in the Southern Ocean. PLoS One 2014; 9:e86452. [PMID: 24516515 PMCID: PMC3905967 DOI: 10.1371/journal.pone.0086452] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 12/15/2013] [Indexed: 02/05/2023] Open
Abstract
Development in foraging behaviour and dietary intake of many vertebrates are age-structured.
Differences in feeding ecology may correlate with ontogenetic shifts in dispersal patterns, and
therefore affect foraging habitat and resource utilization. Such life-history traits have important
implications in interpreting tropho-dynamic linkages. Stable isotope ratios in the whiskers of
sub-yearling southern elephant seals (Mirounga leonina;
n = 12) were used, in conjunction with satellite telemetry and environmental
data, to examine their foraging habitat and diet during their first foraging migration. The trophic
position of seals from Macquarie Island (54°30′S, 158°57′E) was estimated using
stable carbon (δ13C) and nitrogen (δ15N) ratios along the
length of the whisker, which provided a temporal record of prey intake. Satellite-relayed data
loggers provided details on seal movement patterns, which were related to isotopic concentrations
along the whisker. Animals fed in waters south of the Polar Front (>60°S) or within
Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) Statistical Subareas
88.1 and 88.2, as indicated by both their depleted δ13C
(<−20‰) values, and tracking data. They predominantly exploited varying proportions
of mesopelagic fish and squid, and crustaceans, such as euphausiids, which have not been reported as
a prey item for this species. Comparison of isotopic data between sub-yearlings, and 1, 2 and 3 yr
olds indicated that sub-yearlings, limited by their size, dive capabilities and prey capture skills
to feeding higher in the water column, fed at a lower trophic level than older seals. This is
consistent with the consumption of euphausiids and most probably, Antarctic krill (Euphausia
superba), which constitute an abundant, easily accessible source of prey in water masses
used by this age class of seals. Isotopic assessment and concurrent tracking of seals are
successfully used here to identify ontogenetic shifts in broad-scale foraging habitat use and diet
preferences in a highly migratory predator.
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Affiliation(s)
- Andrea Walters
- Institute for Marine and Antarctic Studies, University of
Tasmania, Hobart, Tasmania, Australia
- Antarctic Climate and Ecosystems Cooperative Research
Centre, Hobart, Tasmania, Australia
- * E-mail:
| | - Mary-Anne Lea
- Institute for Marine and Antarctic Studies, University of
Tasmania, Hobart, Tasmania, Australia
| | | | - Iain C. Field
- Marine Mammal Research Group, Department of Environment
and Geography, Macquarie University, Sydney, New South Wales, Australia
| | - Patti Virtue
- Institute for Marine and Antarctic Studies, University of
Tasmania, Hobart, Tasmania, Australia
- Antarctic Climate and Ecosystems Cooperative Research
Centre, Hobart, Tasmania, Australia
| | - Sergei Sokolov
- Commonwealth Scientific and Industrial Research
Organisation Marine and Atmospheric Research, Hobart, Tasmania, Australia
| | - Matt H. Pinkerton
- National Institute of Water and Atmospheric Research Ltd,
Kilbernie, Wellington, New Zealand
| | - Mark A. Hindell
- Institute for Marine and Antarctic Studies, University of
Tasmania, Hobart, Tasmania, Australia
- Antarctic Climate and Ecosystems Cooperative Research
Centre, Hobart, Tasmania, Australia
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Desprez M, McMahon CR, Hindell MA, Harcourt R, Gimenez O. Known unknowns in an imperfect world: incorporating uncertainty in recruitment estimates using multi-event capture-recapture models. Ecol Evol 2013; 3:4658-68. [PMID: 24363895 PMCID: PMC3867902 DOI: 10.1002/ece3.846] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 09/17/2013] [Accepted: 09/19/2013] [Indexed: 11/11/2022] Open
Abstract
Studying the demography of wild animals remains challenging as several of the critical parts of their life history may be difficult to observe in the field. In particular, determining with certainty when an individual breeds for the first time is not always obvious. This can be problematic because uncertainty about the transition from a prebreeder to a breeder state - recruitment - leads to uncertainty in vital rate estimates and in turn in population projection models. To avoid this issue, the common practice is to discard imperfect data from the analyses. However, this practice can generate a bias in vital rate estimates if uncertainty is related to a specific component of the population and reduces the sample size of the dataset and consequently the statistical power to detect effects of biological interest. Here, we compared the demographic parameters assessed from a standard multistate capture-recapture approach to the estimates obtained from the newly developed multi-event framework that specifically accounts for uncertainty in state assessment. Using a comprehensive longitudinal dataset on southern elephant seals, we demonstrated that the multi-event model enabled us to use all the data collected (6639 capture-recapture histories vs. 4179 with the multistate model) by accounting for uncertainty in breeding states, thereby increasing the precision and accuracy of the demographic parameter estimates. The multi-event model allowed us to incorporate imperfect data into demographic analyses. The gain in precision obtained has important implications in the conservation and management of species because limiting uncertainty around vital rates will permit predicting population viability with greater accuracy.
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Affiliation(s)
- Marine Desprez
- Marine Predator Research Group, Department of Biological Sciences, Macquarie UniversityNorth Ryde, 2109, New South Wales, Australia
| | - Clive R McMahon
- Institute for Marine and Antarctic Studies, University of TasmaniaHobart, 7001, Tasmania, Australia
| | - Mark A Hindell
- Institute for Marine and Antarctic Studies, University of TasmaniaHobart, 7001, Tasmania, Australia
| | - Robert Harcourt
- Marine Predator Research Group, Department of Biological Sciences, Macquarie UniversityNorth Ryde, 2109, New South Wales, Australia
| | - Olivier Gimenez
- Centre d'Ecologie Fonctionnelle et Evolutive, campus CNRS, UMR 51751919 Route de Mende, Montpellier Cedex 5, 34293, France
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Schick RS, New LF, Thomas L, Costa DP, Hindell MA, McMahon CR, Robinson PW, Simmons SE, Thums M, Harwood J, Clark JS. Estimating resource acquisition and at-sea body condition of a marine predator. J Anim Ecol 2013; 82:1300-15. [PMID: 23869551 PMCID: PMC4028992 DOI: 10.1111/1365-2656.12102] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 05/13/2013] [Indexed: 02/03/2023]
Abstract
1. Body condition plays a fundamental role in many ecological and evolutionary processes at a variety of scales and across a broad range of animal taxa. An understanding of how body condition changes at fine spatial and temporal scales as a result of interaction with the environment provides necessary information about how animals acquire resources. 2. However, comparatively little is known about intra- and interindividual variation of condition in marine systems. Where condition has been studied, changes typically are recorded at relatively coarse time-scales. By quantifying how fine-scale interaction with the environment influences condition, we can broaden our understanding of how animals acquire resources and allocate them to body stores. 3. Here we used a hierarchical Bayesian state-space model to estimate the body condition as measured by the size of an animal's lipid store in two closely related species of marine predator that occupy different hemispheres: northern elephant seals (Mirounga angustirostris) and southern elephant seals (Mirounga leonina). The observation model linked drift dives to lipid stores. The process model quantified daily changes in lipid stores as a function of the physiological condition of the seal (lipid:lean tissue ratio, departure lipid and departure mass), its foraging location, two measures of behaviour and environmental covariates. 4. We found that physiological condition significantly impacted lipid gain at two time-scales - daily and at departure from the colony - that foraging location was significantly associated with lipid gain in both species of elephant seals and that long-term behavioural phase was associated with positive lipid gain in northern and southern elephant seals. In northern elephant seals, the occurrence of short-term behavioural states assumed to represent foraging were correlated with lipid gain. Lipid gain was a function of covariates in both species. Southern elephant seals performed fewer drift dives than northern elephant seals and gained lipids at a lower rate. 5. We have demonstrated a new way to obtain time series of body condition estimates for a marine predator at fine spatial and temporal scales. This modelling approach accounts for uncertainty at many levels and has the potential to integrate physiological and movement ecology of top predators. The observation model we used was specific to elephant seals, but the process model can readily be applied to other species, providing an opportunity to understand how animals respond to their environment at a fine spatial scale.
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Affiliation(s)
- Robert S Schick
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA; Centre for Research into Ecological and Environmental Modelling, The Observatory, University of St Andrews, St Andrews, KY16 9LZ, UK
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Gil-Delgado JA, Villaescusa JA, Diazmacip ME, Velazquez D, Rico E, Toro M, Quesada A, Camacho A. Minimum population size estimates demonstrate an increase in southern elephant seals (Mirounga leonina) on Livingston Island, maritime Antarctica. Polar Biol 2012. [DOI: 10.1007/s00300-012-1280-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Herrando-Perez S, Delean S, Brook BW, Bradshaw CJA. Decoupling of component and ensemble density feedbacks in birds and mammals. Ecology 2012; 93:1728-40. [PMID: 22919918 DOI: 10.1890/11-1415.1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A component density feedback represents the effect of change in population size on single demographic rates, whereas an ensemble density feedback captures that effect on the overall growth rate of a population. Given that a population's growth rate is a synthesis of the interplay of all demographic rates operating in a population, we test the hypothesis that the strength of ensemble density feedback must augment with increasing strength of component density feedback, using long-term censuses of population size, fertility, and survival rates of 109 bird and mammal populations (97 species). We found that compensatory and depensatory component feedbacks were common (each detected in approximately 50% of the demographic rates). However, component feedback strength only explained <10% of the variation in ensemble feedback strength. To explain why, we illustrate the different sources of decoupling between component and ensemble feedbacks. We argue that the management of anthropogenic impacts on populations using component feedbacks alone is ill-advised, just as managing on the basis of ensemble feedbacks without a mechanistic understanding of the contributions made by its components and environmental variability can lead to suboptimal decisions.
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Affiliation(s)
- Salvador Herrando-Perez
- The Environment Institute and School of Earth and Environmental Sciences, University of Adelaide, South Australia 5005, Australia.
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Authier M, Bentaleb I, Ponchon A, Martin C, Guinet C. Foraging fidelity as a recipe for a long life: foraging strategy and longevity in male Southern Elephant Seals. PLoS One 2012; 7:e32026. [PMID: 22505993 PMCID: PMC3323586 DOI: 10.1371/journal.pone.0032026] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 01/18/2012] [Indexed: 11/24/2022] Open
Abstract
Identifying individual factors affecting life-span has long been of interest for biologists and demographers: how do some individuals manage to dodge the forces of mortality when the vast majority does not? Answering this question is not straightforward, partly because of the arduous task of accurately estimating longevity in wild animals, and of the statistical difficulties in correlating time-varying ecological covariables with a single number (time-to-event). Here we investigated the relationship between foraging strategy and life-span in an elusive and large marine predator: the Southern Elephant Seal (Mirounga leonina). Using teeth recovered from dead males on îles Kerguelen, Southern Ocean, we first aged specimens. Then we used stable isotopic measurements of carbon (δ13C) in dentin to study the effect of foraging location on individual life-span. Using a joint change-point/survival modelling approach which enabled us to describe the ontogenetic trajectory of foraging, we unveiled how a stable foraging strategy developed early in life positively covaried with longevity in male Southern Elephant Seals. Coupled with an appropriate statistical analysis, stable isotopes have the potential to tackle ecological questions of long standing interest but whose answer has been hampered by logistic constraints.
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Affiliation(s)
- Matthieu Authier
- Centre d'Études Biologiques de Chizé, UPR 1934 du CNRS, Villiers-en-Bois, France
- École Doctorale Sciences pour l'Environnement Gay Lussac-Université de Poitiers, France
| | - Ilham Bentaleb
- Institut des Sciences de l'Evolution, UMR 5554 du CNRS, Montpellier, France
| | - Aurore Ponchon
- Institut des Sciences de l'Evolution, UMR 5554 du CNRS, Montpellier, France
- Centre d'Écologie Fonctionnelle et Évolutive, UMR 5175 du CNRS, Montpellier, France
| | - Céline Martin
- Institut des Sciences de l'Evolution, UMR 5554 du CNRS, Montpellier, France
| | - Christophe Guinet
- Centre d'Études Biologiques de Chizé, UPR 1934 du CNRS, Villiers-en-Bois, France
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Authier M, Dragon AC, Richard P, Cherel Y, Guinet C. O' mother where wert thou? Maternal strategies in the southern elephant seal: a stable isotope investigation. Proc Biol Sci 2012; 279:2681-90. [PMID: 22398171 DOI: 10.1098/rspb.2012.0199] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Maternal effects are widespread in ecology and can alter the dynamics of a population. We investigated the impact of maternal foraging strategies on offspring weaning mass--a proxy of maternal foraging success and of offspring survival--in southern elephant seals on îles Kerguelen. Using 4 years of data, we modelled pup weaning mass as a two-component mixture and used blood stable isotope values to discriminate between maternal foraging strategies previously identified from bio-logging studies. Carbon isotope ratio was a strong predictor of weaning mass, but the relationship was non-monotonic in contrast to a priori expectations. Females foraging in the interfrontal zone weaned pups with a smaller mass compared with females foraging in Antarctic waters. Pup mass was positively correlated with a proxy of global primary production in the interfrontal zone for small weanlings. Maternal effects, via a poor foraging efficiency in the 1970s, may help explain the large population decrease observed at that time on îles Kerguelen because of an overall decrease in pup weaning mass, survival and subsequent recruitment.
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OOSTHUIZEN WCHRIS, DE BRUYN PJNICO, BESTER MARTHÁNN. Unmarked individuals in mark-recapture studies: Comparisons of marked and unmarked southern elephant seals at Marion Island. AUSTRAL ECOL 2011. [DOI: 10.1111/j.1442-9993.2011.02316.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Thums M, Bradshaw CJA, Hindelli MA. In situ measures of foraging success and prey encounter reveal marine habitat-dependent search strategies. Ecology 2011; 92:1258-70. [PMID: 21797154 DOI: 10.1890/09-1299.1] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Predators are thought to reduce travel speed and increase turning rate in areas where resources are relatively more abundant, a behavior termed "area-restricted search." However, evidence for this is rare, and few empirical data exist for large predators. Animals exhibiting foraging site fidelity could also be spatially aware of suitable feeding areas based on prior experience; changes in movement patterns might therefore arise from the anticipation of higher prey density. We tested the hypothesis that regions of area-restricted search were associated with a higher number of daily speed spikes (a proxy for potential prey encounter rate) and foraging success in southern elephant seals (Mirounga leonina), a species exhibiting both area-restricted searches and high interannual foraging site fidelity. We used onshore morphological measurements and diving data from archival tags deployed during winter foraging trips. Foraging success was inferred from in situ changes in relative lipid content derived from measured changes in buoyancy, and first-passage time analysis was used to identify area-restricted search behavior. Seals exhibited relatively direct southerly movement on average, with intensive search behavior predominantly located at the distal end of tracks. The probability of being in search mode was positively related to changes in relative lipid content; thus, intensively searched areas were associated with the highest foraging success. However, there was high foraging success during the outward transit even though seals moved through quickly without slowing down and increasing turning rate to exploit these areas. In addition, the probability of being in search mode was negatively related to the number of daily speed spikes. These results suggest that movement patterns represent a response to prior expectation of the location of predictable and profitable resources. Shelf habitat was 4-9 times more profitable than the other habitats, emphasizing the importance of the East Antarctic shelf for this and other predators in the region. We have provided rare empirical data with which to investigate the relationship between predator foraging strategy and prey encounter/ foraging success, underlining the importance of inferring the timing and spatial arrangement of successful food acquisition for interpreting foraging strategies correctly.
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Affiliation(s)
- Michele Thums
- Marine Predator Unit, Institute of Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7001, Australia.
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45
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Authier M, Delord K, Guinet C. Population trends of female Elephant Seals breeding on the Courbet Peninsula, îles Kerguelen. Polar Biol 2010. [DOI: 10.1007/s00300-010-0881-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Lander ME, Loughlin TR, Logsdon MG, VanBlaricom GR, Fadely BS, Fritz LW. Regional differences in the spatial and temporal heterogeneity of oceanographic habitat used by Steller sea lions. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2009; 19:1645-1659. [PMID: 19769109 DOI: 10.1890/08-0159.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Over the past three decades, the decline and altered spatial distribution of the western stock of Steller sea lions (Eumetopias jubatus) in Alaska have been attributed to changes in the distribution or abundance of their prey due to the cumulative effects of fisheries and environmental perturbations. During this period, dietary prey occurrence and diet diversity were related to population decline within metapopulation regions of the western stock of Steller sea lions, suggesting that environmental conditions may be variable among regions. The objective of this study, therefore, was to examine regional differences in the spatial and temporal heterogeneity of oceanographic habitat used by Steller sea lions within the context of recent measures of diet diversity and population trajectories. Habitat use was assessed by deploying satellite-depth recorders and satellite relay data loggers on juvenile Steller sea lions (n = 45) over a five-year period (2000-2004) within four regions of the western stock, including the western, central, and eastern Aleutian Islands, and central Gulf of Alaska. Areas used by sea lions during summer months (June, July, and August) were demarcated using satellite telemetry data and characterized by environmental variables (sea surface temperature [SST] and chlorophyll a [chl a]), which possibly serve as proxies for environmental processes or prey. Spatial patterns of SST diversity and Steller sea lion population trends among regions were fairly consistent with trends reported for diet studies, possibly indicating a link between environmental diversity, prey diversity, and distribution or abundance of Steller sea lions. Overall, maximum spatial heterogeneity coupled with minimal temporal variability of SST appeared to be beneficial for Steller sea lions. In contrast, these patterns were not consistent for chl a, and there appeared to be an ecological threshold. Understanding how Steller sea lions respond to measures of environmental heterogeneity will ultimately be useful for implementing ecosystem management approaches and developing additional conservation strategies.
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Affiliation(s)
- Michelle E Lander
- National Marine Mammal Laboratory, National Marine Fisheries Service, Seattle, Washington 98115, USA.
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McMahon CR, Bester MN, Hindell MA, Brook BW, Bradshaw CJA. Shifting trends: detecting environmentally mediated regulation in long-lived marine vertebrates using time-series data. Oecologia 2008; 159:69-82. [PMID: 18987892 DOI: 10.1007/s00442-008-1205-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Accepted: 10/07/2008] [Indexed: 11/30/2022]
Abstract
Assessing the status and trends in animal populations is essential for effective species conservation and management practices. However, unless time-series abundance data demonstrate rapid and reliable fluctuations, objective appraisal of directionality of trends is problematic. We adopted a multiple-working hypotheses approach based on information-theoretic and Bayesian multi-model inference to examine the population trends and form of intrinsic regulation demonstrated by a long-lived species, the southern elephant seal. We also determined the evidence for density dependence in 11 other well-studied marine mammal species. (1) We tested the type of population regulation for elephant seals from Marion Island (1986-2004) and from 11 other marine mammal species, and (2) we described the trends and behavior of the 19-year population time series at Marion Island to identify changes in population trends. We contrasted five plausible trend models using information-theoretic and Bayesian-inference estimates of model parsimony. Our analyses identified two distinct phases of population growth for this population with the inflexion occurring in 1998. Thus, the population decreased between 1986 and 1997 (-3.7% per annum) and increased between 1997 and 2004 (1.9% per annum). An index of environmental stochasticity, the Southern Oscillation Index, explained some of the variance in r and N. We determined analytically that there was good evidence for density dependence in the Marion Island population and that density dependence was widespread among marine mammal species (67% of species showed evidence for population regulation). This approach demonstrates the potential functionality of a relatively simple technique that can be applied to short time series to identify the type of regulation, and the uncertainty associated with the phenomenon, operating in populations of large mammals.
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Affiliation(s)
- Clive R McMahon
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Pretoria, Gauteng, Republic of South Africa.
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de Bruyn PJN, Tosh CA, Oosthuizen WC, Phalanndwa MV, Bester MN. Temporary marking of unweaned southern elephant seal (Mirounga leonina L.) pups. ACTA ACUST UNITED AC 2008. [DOI: 10.3957/0379-4369-38.2.133] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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50
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Pistorius PA, Bester MN, Hofmeyr GJG, Kirkman SP, Taylor FE. Seasonal survival and the relative cost of first reproduction in adult female southern elephant seals. J Mammal 2008. [DOI: 10.1644/07-mamm-a-219r.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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