1
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Thepault A, Rodrigues ASL, Drago L, Grémillet D. Food chain without giants: modelling the trophic impact of bowhead whaling on little auk populations in the Atlantic Arctic. Proc Biol Sci 2024; 291:20241183. [PMID: 39163979 PMCID: PMC11335397 DOI: 10.1098/rspb.2024.1183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 06/18/2024] [Accepted: 07/23/2024] [Indexed: 08/22/2024] Open
Abstract
In the Atlantic Arctic, bowhead whales (Balaena mysticetus) were nearly exterminated by European whalers between the seventeenth and nineteenth centuries. The collapse of the East Greenland-Svalbard-Barents Sea population, from an estimated 50 000 to a few hundred individuals, drastically reduced predation on mesozooplankton. Here, we tested the hypothesis that this event strongly favoured the demography of the little auk (Alle alle), a zooplanktivorous feeder competitor of bowhead whales and the most abundant seabird in the Arctic. To estimate the effect of bowhead whaling on little auk abundance, we modelled the trophic niche overlap between the two species using deterministic simulations of mesozooplankton spatial distribution. We estimated that bowhead whaling could have led to a 70% increase in northeast Atlantic Arctic little auk populations, from 2.8 to 4.8 million breeding pairs. While corresponding to a major population increase, this is far less than predicted by previous studies. Our study illustrates how a trophic shift can result from the near extirpation of a marine megafauna species, and the methodological framework we developed opens up new opportunities for marine trophic modelling.
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Affiliation(s)
- Amaury Thepault
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
- Mécanismes adaptatifs et évolution (MECADEV UMR 7179), Muséum National d’Histoire Naturelle, Centre National de la Recherche Scientifique, Brunoy, France
| | | | - Laetitia Drago
- Laboratoire d’Océanographie de Villefranche-sur-mer, Sorbonne Université, Villefranche-sur-mer, France
- Sorbonne Université UMR 7159 CNRS-IRD-MNHN, LOCEAN-IPSL, Sorbonne Université, Paris, France
| | - David Grémillet
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
- Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Cape Town, South Africa
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2
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Hirtle NO, Stepanuk JEF, Heywood EI, Christiansen F, Thorne LH. Integrating
3D
models with morphometric measurements to improve volumetric estimates in marine mammals. Methods Ecol Evol 2022. [DOI: 10.1111/2041-210x.13962] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nathan O. Hirtle
- Stony Brook University School of Marine and Atmospheric Sciences Stony Brook NY USA
| | | | - Eleanor I. Heywood
- Stony Brook University School of Marine and Atmospheric Sciences Stony Brook NY USA
| | - Fredrik Christiansen
- Aarhus Institute of Advanced Studies Aarhus C Denmark
- Zoophysiology, Department of Biology Aarhus University Aarhus C Denmark
| | - Lesley H. Thorne
- Stony Brook University School of Marine and Atmospheric Sciences Stony Brook NY USA
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3
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Direct evidence of a prey depletion "halo" surrounding a pelagic predator colony. Proc Natl Acad Sci U S A 2021; 118:2101325118. [PMID: 34260406 DOI: 10.1073/pnas.2101325118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Colonially breeding birds and mammals form some of the largest gatherings of apex predators in the natural world and have provided model systems for studying mechanisms of population regulation in animals. According to one influential hypothesis, intense competition for food among large numbers of spatially constrained foragers should result in a zone of prey depletion surrounding such colonies, ultimately limiting their size. However, while indirect and theoretical support for this phenomenon, known as "Ashmole's halo," has steadily accumulated, direct evidence remains exceptionally scarce. Using a combination of vessel-based surveys and Global Positioning System tracking, we show that pelagic seabirds breeding at the tropical island that first inspired Ashmole's hypothesis do indeed deplete their primary prey species (flying fish; Exocoetidae spp.) over a considerable area, with reduced prey density detectable >150 km from the colony. The observed prey gradient was mirrored by an opposing trend in seabird foraging effort, could not be explained by confounding environmental variability, and can be approximated using a mechanistic consumption-dispersion model, incorporating realistic rates of seabird predation and random prey dispersal. Our results provide a rare view of the resource footprint of a pelagic seabird colony and reveal how aggregations of these central-place foraging, marine top predators profoundly influence the oceans that surround them.
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4
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Sydeman WJ, Schoeman DS, Thompson SA, Hoover BA, García-Reyes M, Daunt F, Agnew P, Anker-Nilssen T, Barbraud C, Barrett R, Becker PH, Bell E, Boersma PD, Bouwhuis S, Cannell B, Crawford RJM, Dann P, Delord K, Elliott G, Erikstad KE, Flint E, Furness RW, Harris MP, Hatch S, Hilwig K, Hinke JT, Jahncke J, Mills JA, Reiertsen TK, Renner H, Sherley RB, Surman C, Taylor G, Thayer JA, Trathan PN, Velarde E, Walker K, Wanless S, Warzybok P, Watanuki Y. Hemispheric asymmetry in ocean change and the productivity of ecosystem sentinels. Science 2021; 372:980-983. [PMID: 34045354 DOI: 10.1126/science.abf1772] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 04/20/2021] [Indexed: 11/02/2022]
Abstract
Climate change and other human activities are causing profound effects on marine ecosystem productivity. We show that the breeding success of seabirds is tracking hemispheric differences in ocean warming and human impacts, with the strongest effects on fish-eating, surface-foraging species in the north. Hemispheric asymmetry suggests the need for ocean management at hemispheric scales. For the north, tactical, climate-based recovery plans for forage fish resources are needed to recover seabird breeding productivity. In the south, lower-magnitude change in seabird productivity presents opportunities for strategic management approaches such as large marine protected areas to sustain food webs and maintain predator productivity. Global monitoring of seabird productivity enables the detection of ecosystem change in remote regions and contributes to our understanding of marine climate impacts on ecosystems.
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Affiliation(s)
| | - D S Schoeman
- Global-Change Ecology Research Group, School of Science, Technology and Engineering, University of the Sunshine Coast, Sippy Downs, Queensland, Australia.,Centre for African Conservation Ecology, Department of Zoology, Nelson Mandela University, Gqeberha, South Africa
| | | | | | | | - F Daunt
- UK Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, UK
| | - P Agnew
- Oamaru Blue Penguin Colony, Oamaru, New Zealand
| | - T Anker-Nilssen
- Norwegian Institute for Nature Research (NINA), Trondheim, Norway
| | - C Barbraud
- Centre d'Etudes Biologiques de Chizé, CNRS UMR7372, Villiers en Bois, France
| | - R Barrett
- UiT The Arctic University of Norway, Tromsø, Norway
| | - P H Becker
- Institute of Avian Research, Wilhelmshaven, Germany
| | - E Bell
- Wildlife Management International, Blenheim, New Zealand
| | - P D Boersma
- Center for Ecosystem Sentinels, Department of Biology, University of Washington, Seattle, WA, USA
| | - S Bouwhuis
- Institute of Avian Research, Wilhelmshaven, Germany
| | - B Cannell
- Murdoch University, Murdoch, Western Australia, and University of Western Australia, Perth, Western Australia
| | - R J M Crawford
- Department of Environment, Forestry and Fisheries, Cape Town, South Africa
| | - P Dann
- Phillip Island Nature Parks, Cowes, Victoria, Australia
| | - K Delord
- Centre d'Etudes Biologiques de Chizé, CNRS UMR7372, Villiers en Bois, France
| | - G Elliott
- New Zealand Department of Conservation, Wellington, New Zealand
| | - K E Erikstad
- Norwegian Institute for Nature Research (NINA), FRAM Centre, Tromsø, Norway and Centre for Biodiversity Dynamics (CBD), Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - E Flint
- U.S. Fish and Wildlife Service, Honolulu, HI, USA
| | - R W Furness
- University of Glasgow, Glasgow, Scotland, UK
| | - M P Harris
- UK Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, UK
| | - S Hatch
- Institute for Seabird Research and Conservation, Anchorage, AK, USA
| | - K Hilwig
- U.S. Fish and Wildlife Service, Anchorage, AK, USA
| | - J T Hinke
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, La Jolla, CA, USA
| | - J Jahncke
- Point Blue Conservation Science, Petaluma, CA, USA
| | | | - T K Reiertsen
- Norwegian Institute for Nature Research (NINA), FRAM Centre, Tromsø, Norway
| | - H Renner
- U.S. Fish and Wildlife Service, Anchorage, AK, USA
| | - R B Sherley
- Centre for Ecology and Conservation, University of Exeter, Cornwall, UK
| | - C Surman
- Halfmoon Biosciences, Ocean Beach, Western Australia, Australia
| | - G Taylor
- New Zealand Department of Conservation, Wellington, New Zealand
| | | | | | - E Velarde
- Universidad Veracruzana, Veracruz, Mexico
| | - K Walker
- New Zealand Department of Conservation, Wellington, New Zealand
| | - S Wanless
- UK Centre for Ecology and Hydrology, Bush Estate, Penicuik, Midlothian, UK
| | - P Warzybok
- Point Blue Conservation Science, Petaluma, CA, USA
| | - Y Watanuki
- Hokkaido University, Hakodate, Hokkaido, Japan
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5
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Wing SR, Wing LC, O’Connell-Milne SA, Barr D, Stokes D, Genovese S, Leichter JJ. Penguins and Seals Transport Limiting Nutrients Between Offshore Pelagic and Coastal Regions of Antarctica Under Changing Sea Ice. Ecosystems 2020. [DOI: 10.1007/s10021-020-00578-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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6
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Chen X, Cheng X, Zhang B, Meng H, Wu D, Zhang M, Ji M, Li X. Lagged response of Adélie penguin (Pygoscelis adeliae) abundance to environmental variability in the Ross Sea, Antarctica. Polar Biol 2020. [DOI: 10.1007/s00300-020-02743-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Drivers of concentrated predation in an Antarctic marginal-ice-zone food web. Sci Rep 2020; 10:7282. [PMID: 32350362 PMCID: PMC7190673 DOI: 10.1038/s41598-020-63875-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 04/03/2020] [Indexed: 02/05/2023] Open
Abstract
Predators impact preyscapes (3-D distribution of forage species) by consuming prey according to their abilities or by altering prey behavior as they avoid being consumed. We elucidate prey (Antarctic silverfish[Pleuragramma antarctica] and crystal krill[Euphausia chrystallorophias]) responses to predation associated with the marginal ice zone (MIZ) of the McMurdo Sound, Antarctica, polynya. Prey abundance and habitat was sampled across a 30 × 15 km area by remotely-operated vehicle, and included locations that were accessible (ice edge) or inaccessible (solid fast ice) to air-breathing predators. Prey and habitat sampling coincided with bio-logging of Adélie penguins and observations of other air-breathing predators (penguins, seals, and whales), all of which were competing for the same prey. Adélie penguins dived deeper, and more frequently, near the ice edge. Lowered abundance of krill at the ice edge indicated they were depleted or were responding to increased predation and/or higher light levels along the ice edge. Penguin diet shifted increasingly to silverfish from krill during sampling, and was correlated with the arrival of krill-eating whales. Behaviorally-mediated, high trophic transfer characterizes the McMurdo Sound MIZ, and likely other MIZs, warranting more specific consideration in food web models and conservation efforts.
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8
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Rumolo P, Zappes IA, Fabiani A, Barra M, Rakaj A, Palozzi R, Allegrucci G. The diet of Weddell seals (Leptonychotes weddellii) in Terra Nova Bay using stable isotope analysis. THE EUROPEAN ZOOLOGICAL JOURNAL 2020. [DOI: 10.1080/24750263.2020.1720832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Affiliation(s)
- P. Rumolo
- Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche, Naples, Italy
| | - I. A. Zappes
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - A. Fabiani
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - M. Barra
- Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche, Naples, Italy
| | - A. Rakaj
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - R. Palozzi
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | - G. Allegrucci
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
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9
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Rogers AD, Frinault BAV, Barnes DKA, Bindoff NL, Downie R, Ducklow HW, Friedlaender AS, Hart T, Hill SL, Hofmann EE, Linse K, McMahon CR, Murphy EJ, Pakhomov EA, Reygondeau G, Staniland IJ, Wolf-Gladrow DA, Wright RM. Antarctic Futures: An Assessment of Climate-Driven Changes in Ecosystem Structure, Function, and Service Provisioning in the Southern Ocean. ANNUAL REVIEW OF MARINE SCIENCE 2020; 12:87-120. [PMID: 31337252 DOI: 10.1146/annurev-marine-010419-011028] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this article, we analyze the impacts of climate change on Antarctic marine ecosystems. Observations demonstrate large-scale changes in the physical variables and circulation of the Southern Ocean driven by warming, stratospheric ozone depletion, and a positive Southern Annular Mode. Alterations in the physical environment are driving change through all levels of Antarctic marine food webs, which differ regionally. The distributions of key species, such as Antarctic krill, are also changing. Differential responses among predators reflect differences in species ecology. The impacts of climate change on Antarctic biodiversity will likely vary for different communities and depend on species range. Coastal communities and those of sub-Antarctic islands, especially range-restricted endemic communities, will likely suffer the greatest negative consequences of climate change. Simultaneously, ecosystem services in the Southern Ocean will likely increase. Such decoupling of ecosystem services and endemic species will require consideration in the management of human activities such as fishing in Antarctic marine ecosystems.
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Affiliation(s)
- A D Rogers
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom;
- REV Ocean, 1366 Lysaker, Norway
| | - B A V Frinault
- School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, United Kingdom
| | - D K A Barnes
- British Antarctic Survey, Natural Environment Research Council, Cambridge CB3 0ET, United Kingdom
| | - N L Bindoff
- Antarctic Climate and Ecosystems Cooperative Research Centre and CSIRO Oceans and Atmospheres, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - R Downie
- WWF, Living Planet Centre, Surrey GU21 4LL, United Kingdom
| | - H W Ducklow
- Lamont-Doherty Earth Observatory and Department of Earth and Environmental Sciences, Columbia University, Palisades, New York 10964-8000, USA
| | - A S Friedlaender
- Institute for Marine Sciences, University of California, Santa Cruz, California 95060, USA
| | - T Hart
- Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom;
| | - S L Hill
- British Antarctic Survey, Natural Environment Research Council, Cambridge CB3 0ET, United Kingdom
| | - E E Hofmann
- Center for Coastal Physical Oceanography, Old Dominion University, Norfolk, Virginia 23508, USA
| | - K Linse
- British Antarctic Survey, Natural Environment Research Council, Cambridge CB3 0ET, United Kingdom
| | - C R McMahon
- Integrated Marine Observing System Animal Tracking Facility, Sydney Institute of Marine Science, Sydney, New South Wales 2088, Australia
| | - E J Murphy
- British Antarctic Survey, Natural Environment Research Council, Cambridge CB3 0ET, United Kingdom
| | - E A Pakhomov
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
- Aquatic Ecosystems Research Lab, Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - G Reygondeau
- Aquatic Ecosystems Research Lab, Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - I J Staniland
- British Antarctic Survey, Natural Environment Research Council, Cambridge CB3 0ET, United Kingdom
| | - D A Wolf-Gladrow
- Alfred-Wegener-Institut Helmholtz Zentrum für Polar- und Meeresforschung (AWI), 27570 Bremerhaven, Germany
| | - R M Wright
- Tyndall Centre, School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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10
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Divergent trophic responses of sympatric penguin species to historic anthropogenic exploitation and recent climate change. Proc Natl Acad Sci U S A 2019; 116:25721-25727. [PMID: 31792174 DOI: 10.1073/pnas.1913093116] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The Southern Ocean is in an era of significant change. Historic overharvesting of marine mammals and recent climatic warming have cascading impacts on resource availability and, in turn, ecosystem structure and function. We examined trophic responses of sympatric chinstrap (Pygoscelis antarctica) and gentoo (Pygoscelis papua) penguins to nearly 100 y of shared environmental change in the Antarctic Peninsula region using compound-specific stable isotope analyses of museum specimens. A century ago, gentoo penguins fed almost exclusively on low-trophic level prey, such as krill, during the peak of historic overexploitation of marine mammals, which was hypothesized to have resulted in a krill surplus. In the last 40 y, gentoo penguin trophic position has increased a full level as krill declined in response to recent climate change, increased competition from recovering marine mammal populations, and the development of a commercial krill fishery. A shifting isotopic baseline supporting gentoo penguins suggests a concurrent increase in coastal productivity over this time. In contrast, chinstrap penguins exhibited no change in trophic position, despite variation in krill availability over the past century. The specialized foraging niche of chinstrap penguins likely renders them more sensitive to changes in krill availability, relative to gentoo penguins, as evinced by their declining population trends in the Antarctic Peninsula over the past 40 y. Over the next century, similarly divergent trophic and population responses are likely to occur among Antarctic krill predators if climate change and other anthropogenic impacts continue to favor generalist over specialist species.
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11
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Lescroël A, Ballard G, Massaro M, Dugger K, Jennings S, Pollard A, Porzig E, Schmidt A, Varsani A, Grémillet D, Ainley D. Evidence of age-related improvement in the foraging efficiency of Adélie penguins. Sci Rep 2019; 9:3375. [PMID: 30833598 PMCID: PMC6399253 DOI: 10.1038/s41598-019-39814-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 01/30/2019] [Indexed: 11/21/2022] Open
Abstract
Age variation in reproductive performance is well-documented but the mechanisms underlying this variation remain unclear. Foraging efficiency is likely to be a key source of demographic variation as it determines the amount of energy that can be invested in fitness-related activities. Evidence of age-related changes in the foraging efficiency of adult seabirds is scarce and inconsistent. We investigated the effects of age on the foraging efficiency of breeding Adélie penguins, a relatively short-lived seabird species, in order to gain a broader perspective on the processes driving variation in ageing rates. We found support for a positive effect of age, either linear or levelling off at old ages, on both our proxies for daily catch rate and catch per unit effort. Across all age classes, males were more performant foragers than females. We found no strong evidence for differing ageing patterns between sexes or individual quality levels, and no evidence for senescence. We infer that continuous individual improvement could be responsible for a larger amount of the variation in foraging efficiency with age at our study site, compared with selective disappearance of underperforming phenotypes. The different results reported by other studies highlight the need to conduct longitudinal studies across a range of species in different environments.
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Affiliation(s)
- Amélie Lescroël
- Point Blue Conservation Science, Petaluma, CA, 94954, USA. .,Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier, France.
| | - Grant Ballard
- Point Blue Conservation Science, Petaluma, CA, 94954, USA
| | - Melanie Massaro
- School of Environmental Sciences, Institute for Land, Water and Society, Charles Sturt University, Albury, NSW, 2640, Australia
| | - Katie Dugger
- U.S. Geological Survey, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon, USA
| | - Scott Jennings
- Point Blue Conservation Science, Petaluma, CA, 94954, USA.,U.S. Geological Survey, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, Corvallis, Oregon, USA
| | - Annie Pollard
- Point Blue Conservation Science, Petaluma, CA, 94954, USA
| | | | - Annie Schmidt
- Point Blue Conservation Science, Petaluma, CA, 94954, USA
| | - Arvind Varsani
- The Biodesign Center for Fundamental and Applied Microbiomics, Center for Evolution and Medicine, School of Life sciences, Arizona State University, Tempe, Arizona, USA.,Structural Biology Research Unit, Department of Clinical Laboratory Sciences, University of Cape Town, Observatory, Cape Town, South Africa
| | - David Grémillet
- Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier, France.,FitzPatrick Institute, DST/NRF centre of excellence at the University of Cape Town, Rondebosch, 7701, South Africa
| | - David Ainley
- H.T. Harvey & Associates, Los Gatos, California, USA
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12
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Furey NB, Armstrong JB, Beauchamp DA, Hinch SG. Migratory coupling between predators and prey. Nat Ecol Evol 2018; 2:1846-1853. [PMID: 30467414 DOI: 10.1038/s41559-018-0711-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 10/04/2018] [Indexed: 11/09/2022]
Abstract
Animal migrations act to couple ecosystems and are undertaken by some of the world's most endangered taxa. Predators often exploit migrant prey, but the movements taken by these consumers are rarely studied or understood. We define such movements, where migrant prey induce large-scale movements of predators, as migratory coupling. Migratory coupling can have ecological consequences for the participating prey, predators and the communities they traverse across the landscape. We review examples of migratory coupling in the literature and provide hypotheses regarding conditions favourable for their occurrence. We also provide a framework for interactions induced by migratory coupling and demonstrate their potential community-level impacts by examining other forms of spatial shifts in predators. Migratory coupling integrates the fields of landscape, movement, food web and community ecologies, and represents an understudied frontier in ecology.
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Affiliation(s)
- Nathan B Furey
- Department of Biological Sciences, University of New Hampshire, Durham, NH, USA. .,Department of Forest and Conservation Sciences, Pacific Salmon Ecology and Conservation Laboratory, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Jonathan B Armstrong
- Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, USA
| | - David A Beauchamp
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - Scott G Hinch
- Department of Forest and Conservation Sciences, Pacific Salmon Ecology and Conservation Laboratory, University of British Columbia, Vancouver, British Columbia, Canada
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13
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Hückstädt LA, McCarthy MD, Koch PL, Costa DP. What difference does a century make? Shifts in the ecosystem structure of the Ross Sea, Antarctica, as evidenced from a sentinel species, the Weddell seal. Proc Biol Sci 2017; 284:20170927. [PMID: 28855359 PMCID: PMC5577480 DOI: 10.1098/rspb.2017.0927] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 07/24/2017] [Indexed: 01/29/2023] Open
Abstract
The arrival of humans to Antarctica's Ross Sea (100+ years ago) led to a slow, but sustained increase in human activities in the area. To investigate if human presence has influenced the structure of the ecosystem over the last century, we compared historical (ca 100 years old) and modern samples of a sentinel species, the Weddell seal (Leptonychotes weddellii), using both bulk tissue and compound-specific stable isotope analysis. The historical isotopic niche of Weddell seals was over five times larger than the modern niche. The isotopic values of individual amino acids showed a clear segregation between historical and modern samples, indicative of differences at the base of the trophic web. Further, we found no significant differences in the trophic position of Weddell seals between the two periods. Our study revealed that the Ross Sea has undergone detectable changes (i.e. in the primary producers community) in the last century, but the presence of humans has not disrupted trophic interactions supporting Weddell seals.
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Affiliation(s)
- Luis A Hückstädt
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Matthew D McCarthy
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Paul L Koch
- Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA, USA
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
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14
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15
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How overfishing a large piscine mesopredator explains growth in Ross Sea penguin populations: A framework to better understand impacts of a controversial fishery. Ecol Modell 2017. [DOI: 10.1016/j.ecolmodel.2016.12.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Youngflesh C, Jenouvrier S, Li Y, Ji R, Ainley DG, Ballard G, Barbraud C, Delord K, Dugger KM, Emmerson LM, Fraser WR, Hinke JT, Lyver PO, Olmastroni S, Southwell CJ, Trivelpiece SG, Trivelpiece WZ, Lynch HJ. Circumpolar analysis of the Adélie Penguin reveals the importance of environmental variability in phenological mismatch. Ecology 2017; 98:940-951. [DOI: 10.1002/ecy.1749] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 11/14/2016] [Accepted: 12/08/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Casey Youngflesh
- Department of Ecology and Evolution Stony Brook University Stony Brook New York 11790 USA
| | - Stephanie Jenouvrier
- Biology Department Woods Hole Oceanographic Institution Woods Hole Massachusetts 02543 USA
- Centre d'Etudes Biologiques de Chizé UMR 7372 Centre National de la Recherche Scientifique/Universite La Rochelle Villiers en Bois FR‐79360 France
| | - Yun Li
- University of South Florida, College of Marine Science St. Petersburg Florida 33701 USA
| | - Rubao Ji
- Biology Department Woods Hole Oceanographic Institution Woods Hole Massachusetts 02543 USA
| | | | - Grant Ballard
- Point Blue Conservation Science Petaluma California 94954 USA
| | - Christophe Barbraud
- Centre d'Etudes Biologiques de Chizé UMR 7372 Centre National de la Recherche Scientifique/Universite La Rochelle Villiers en Bois FR‐79360 France
| | - Karine Delord
- Centre d'Etudes Biologiques de Chizé UMR 7372 Centre National de la Recherche Scientifique/Universite La Rochelle Villiers en Bois FR‐79360 France
| | - Katie M. Dugger
- US Geological Survey Oregon Cooperative Fish and Wildlife Research Unit Department of Fisheries and Wildlife Oregon State University Corvallis Oregon 97331 USA
| | - Louise M. Emmerson
- Department of the Environment Australian Antarctic Division Kingston Tasmania 7050 Australia
| | | | - Jefferson T. Hinke
- Antarctic Ecosystem Research Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration La Jolla California 92037 USA
| | | | - Silvia Olmastroni
- Dipartimento di Scienze Fisiche, della Terra e dell'Ambiente Università degli Studi di Siena Siena 53100 Italy
- Museo Nazionale dell'Antartide Sezione di Siena Siena 53100 Italy
| | - Colin J. Southwell
- Department of the Environment Australian Antarctic Division Kingston Tasmania 7050 Australia
| | - Susan G. Trivelpiece
- Antarctic Ecosystem Research Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration La Jolla California 92037 USA
| | - Wayne Z. Trivelpiece
- Antarctic Ecosystem Research Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration La Jolla California 92037 USA
| | - Heather J. Lynch
- Department of Ecology and Evolution Stony Brook University Stony Brook New York 11790 USA
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17
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Spatio-temporal occurrence patterns of cetaceans near Ross Island, Antarctica, 2002–2015: implications for food web dynamics. Polar Biol 2017. [DOI: 10.1007/s00300-017-2100-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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18
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Glen AS, Pech RP, Davey C, Molsher RL. Raptors vs aliens: can indigenous birds of prey help control invasive predators? NEW ZEALAND JOURNAL OF ZOOLOGY 2016. [DOI: 10.1080/03014223.2016.1261910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- A. S. Glen
- Landcare Research, Private Bag 92170, Auckland 1142, New Zealand
| | - R. P. Pech
- Landcare Research, PO Box 69040, Lincoln 7640, New Zealand
| | - C. Davey
- 24 Bardsley Place, Holt, Canberra, ACT 2615, Australia
| | - R. L. Molsher
- Department of Environment, Water and Natural Resources, PO Box 39, Kingscote, Kangaroo Island SA 5223, Australia
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19
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Paterson JT, Rotella JJ, Arrigo KR, Garrott RA. Tight coupling of primary production and marine mammal reproduction in the Southern Ocean. Proc Biol Sci 2016; 282:20143137. [PMID: 25854885 DOI: 10.1098/rspb.2014.3137] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Polynyas are areas of open water surrounded by sea ice and are important sources of primary production in high-latitude marine ecosystems. The magnitude of annual primary production in polynyas is controlled by the amount of exposure to solar radiation and sensitivity to changes in sea-ice extent. The degree of coupling between primary production and production by upper trophic-level consumers in these environments is not well understood, which prevents reliable predictions about population trajectories for species at higher trophic levels under potential future climate scenarios. In this study, we find a strong, positive relationship between annual primary production in an Antarctic polynya and pup production by ice-dependent Weddell seals. The timing of the relationship suggests reproductive effort increases to take advantage of high primary production occurring in the months after the birth pulse. Though the proximate causal mechanism is unknown, our results indicate tight coupling between organisms at disparate trophic levels on a short timescale, deepen our understanding of marine ecosystem processes, and raise interesting questions about why such coupling exists and what implications it has for understanding high-latitude ecosystems.
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Affiliation(s)
| | - Jay J Rotella
- Department of Ecology, Montana State University, Bozeman, MT 59717, USA
| | - Kevin R Arrigo
- Department of Environmental Earth System Science, Stanford University, Stanford, CA 94305-4216, USA
| | - Robert A Garrott
- Department of Ecology, Montana State University, Bozeman, MT 59717, USA
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20
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Jennings S, Varsani A, Dugger KM, Ballard G, Ainley DG. Sex-Based Differences in Adélie Penguin (Pygoscelis adeliae) Chick Growth Rates and Diet. PLoS One 2016; 11:e0149090. [PMID: 26934698 PMCID: PMC4775033 DOI: 10.1371/journal.pone.0149090] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 01/27/2016] [Indexed: 02/07/2023] Open
Abstract
Sexually size-dimorphic species must show some difference between the sexes in growth rate and/or length of growing period. Such differences in growth parameters can cause the sexes to be impacted by environmental variability in different ways, and understanding these differences allows a better understanding of patterns in productivity between individuals and populations. We investigated differences in growth rate and diet between male and female Adélie Penguin (Pygoscelis adeliae) chicks during two breeding seasons at Cape Crozier, Ross Island, Antarctica. Adélie Penguins are a slightly dimorphic species, with adult males averaging larger than adult females in mass (~11%) as well as bill (~8%) and flipper length (~3%). We measured mass and length of flipper, bill, tibiotarsus, and foot at 5-day intervals for 45 male and 40 female individually-marked chicks. Chick sex was molecularly determined from feathers. We used linear mixed effects models to estimate daily growth rate as a function of chick sex, while controlling for hatching order, brood size, year, and potential variation in breeding quality between pairs of parents. Accounting for season and hatching order, male chicks gained mass an average of 15.6 g d(-1) faster than females. Similarly, growth in bill length was faster for males, and the calculated bill size difference at fledging was similar to that observed in adults. There was no evidence for sex-based differences in growth of other morphological features. Adélie diet at Ross Island is composed almost entirely of two species--one krill (Euphausia crystallorophias) and one fish (Pleuragramma antarctica), with fish having a higher caloric value. Using isotopic analyses of feather samples, we also determined that male chicks were fed a higher proportion of fish than female chicks. The related differences in provisioning and growth rates of male and female offspring provides a greater understanding of the ways in which ecological factors may impact the two sexes differently.
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Affiliation(s)
- Scott Jennings
- Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, United States of America
| | - Arvind Varsani
- School of Biological Sciences and Biomolecular Interaction Centre, University of Canterbury, Private Bag 4800, Christchurch, 8140, New Zealand.,Electron Microscope Unit, Division of Medical Biochemistry, Department of Clinical Laboratory Sciences, University of Cape Town, Observatory, 7700, South Africa.,Department of Plant Pathology and Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, United States of America
| | - Katie M Dugger
- U.S. Geological Survey, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, United States of America
| | - Grant Ballard
- Point Blue Conservation Science, Petaluma, CA, United States of America
| | - David G Ainley
- H.T. Harvey and Associates, Los Gatos, CA, United States of America
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21
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Piñones A, Hofmann EE, Dinniman MS, Davis LB. Modeling the transport and fate of euphausiids in the Ross Sea. Polar Biol 2015. [DOI: 10.1007/s00300-015-1798-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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22
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Widmann M, Kato A, Raymond B, Angelier F, Arthur B, Chastel O, Pellé M, Raclot T, Ropert-Coudert Y. Habitat use and sex-specific foraging behaviour of Adélie penguins throughout the breeding season in Adélie Land, East Antarctica. MOVEMENT ECOLOGY 2015; 3:30. [PMID: 26392864 PMCID: PMC4576371 DOI: 10.1186/s40462-015-0052-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 09/06/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND Marine predators are ecosystem sentinels because their foraging behaviour and reproductive success reflect the variability occurring in the lower trophic levels of the ecosystem. In an era of environmental change, monitoring top predators species can provide valuable insights into the zones of ecological importance that need to be protected. In this context, we monitored the Adélie penguin (Pygoscelis adeliae) as a bio-indicator near Dumont d'Urville, an area of the East Antarctic sector currently being considered for the establishment of a Marine Protected Area (MPA), using GPS-based tracking tags during the 2012/13 austral summer breeding season. RESULTS The habitat use and foraging areas of the penguins differed by breeding stage and sex and were strongly associated with patterns in bathymetry and sea-ice distribution. The first trips, undertaken during the incubation phase, were longer than those during the guard phase and were associated with the northern limit of the sea-ice extent. During the guard phase, birds strongly depended on access to a polynya, a key feature in Antarctic marine ecosystem, in the vicinity of the colony. The opening of the ice-free area was synchronous with the hatching of chicks. Moreover, a sex-specific use of foraging habitat observed only after hatching suggests sex-specific differences in the diet in response to intra-specific competition. CONCLUSIONS Sea-ice features that could be affected by the climate change were important factors for the use of foraging habitat by the Adélie penguins. The extent of the foraging area observed in this study is congruent with the area of the proposed MPA. However, both penguin behavior and their environment should be monitored carefully.
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Affiliation(s)
- Michel Widmann
- />Ecole Normale Supérieure de Lyon, 46 allée d’Italie, 96364, Lyon, Cedex 07 France
- />CNRS, UMR7178, 67037 Strasbourg, France
| | - Akiko Kato
- />CNRS, UMR7178, 67037 Strasbourg, France
- />Université de Strasbourg, IPHC, 23 rue Becquerel, 67087 Strasbourg, France
- />Centre d’Etudes Biologiques de Chizé, CNRS UPR 1934, 79360 Villiers-en-Bois, France
| | - Ben Raymond
- />Australian Antarctic Division, Department of the Environment, Australian Government, Channel Highway, Kingston, 7050 Australia
- />Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7001 Australia
| | - Frédéric Angelier
- />Centre d’Etudes Biologiques de Chizé, CNRS UPR 1934, 79360 Villiers-en-Bois, France
| | - Benjamin Arthur
- />Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, TAS 7001 Australia
| | - Olivier Chastel
- />Centre d’Etudes Biologiques de Chizé, CNRS UPR 1934, 79360 Villiers-en-Bois, France
| | | | - Thierry Raclot
- />CNRS, UMR7178, 67037 Strasbourg, France
- />Université de Strasbourg, IPHC, 23 rue Becquerel, 67087 Strasbourg, France
| | - Yan Ropert-Coudert
- />CNRS, UMR7178, 67037 Strasbourg, France
- />Université de Strasbourg, IPHC, 23 rue Becquerel, 67087 Strasbourg, France
- />Centre d’Etudes Biologiques de Chizé, CNRS UPR 1934, 79360 Villiers-en-Bois, France
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23
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Houghton J, Baird RW, Emmons CK, Hanson MB. Changes in the Occurrence and Behavior of Mammal-Eating Killer Whales in Southern British Columbia and Washington State, 1987–2010. NORTHWEST SCIENCE 2015. [DOI: 10.3955/046.089.0207] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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24
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Kelley NP, Pyenson ND. Evolutionary innovation and ecology in marine tetrapods from the Triassic to the Anthropocene. Science 2015; 348:aaa3716. [DOI: 10.1126/science.aaa3716] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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25
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Oppel S, Beard A, Fox D, Mackley E, Leat E, Henry L, Clingham E, Fowler N, Sim J, Sommerfeld J, Weber N, Weber S, Bolton M. Foraging distribution of a tropical seabird supports Ashmole’s hypothesis of population regulation. Behav Ecol Sociobiol 2015. [DOI: 10.1007/s00265-015-1903-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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26
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Pozzi LM, García Borboroglu P, Boersma PD, Pascual MA. Population regulation in Magellanic penguins: what determines changes in colony size? PLoS One 2015; 10:e0119002. [PMID: 25786254 PMCID: PMC4364706 DOI: 10.1371/journal.pone.0119002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Accepted: 01/26/2015] [Indexed: 02/01/2023] Open
Abstract
Seabirds are often studied at individual colonies, but the confounding effects of emigration and mortality processes in open populations may lead to inappropriate conclusions on the mechanisms underlying population changes. Magellanic penguin (Spheniscus magellanicus) colonies of variable population sizes are distributed along the Argentine coastline. In recent decades, several population and distributional changes have occurred, with some colonies declining and others newly established or increasing. We integrated data of eight colonies scattered along ∼600 km in Northern Patagonia (from 41°26´S, 65°01´W to 45°11´S, 66°30´W, Rio Negro and Chubut provinces) and conducted analysis in terms of their growth rates, production of young and of the dependence of those vital rates on colony age, size, and location. We contrasted population trends estimated from abundance data with those derived from population modeling to understand if observed growth rates were attainable under closed population scenarios. Population trends were inversely related to colony size, suggesting a density dependent growth pattern. All colonies located in the north--which were established during the last decades--increased at high rates, with the smallest, recently established colonies growing at the fastest rate. In central-southern Chubut, where colonies are the oldest, the largest breeding aggregations declined, but smaller colonies remained relatively stable. Results provided strong evidence that dispersal played a major role in driving local trends. Breeding success was higher in northern colonies, likely mediated by favorable oceanographic conditions. However, mean foraging distance and body condition of chicks at fledging were influenced by colony size. Recruitment of penguins in the northern area may have been triggered by a combination of density dependence, likely exacerbated by less favorable oceanographic conditions in the southern sector. Our results reaffirm the idea that individual colony trends do not provide confident indicators of population health, highlighting the need to redefine the scale for the study of population changes.
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Affiliation(s)
- Luciana M Pozzi
- Centro Nacional Patagónico (CONICET), Boulevard Brown 2915, 9120 Puerto Madryn, Chubut, Argentina
| | - Pablo García Borboroglu
- Centro Nacional Patagónico (CONICET), Boulevard Brown 2915, 9120 Puerto Madryn, Chubut, Argentina; Global Penguin Society, Seattle, Washington, United States of America; Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - P Dee Boersma
- Global Penguin Society, Seattle, Washington, United States of America; Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Miguel A Pascual
- Centro Nacional Patagónico (CONICET), Boulevard Brown 2915, 9120 Puerto Madryn, Chubut, Argentina; Universidad Nacional de la Patagonia San Juan Bosco, Boulevard Brown S/N, 9120, Puerto Madryn, Chubut, Argentina
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27
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Surma S, Pakhomov EA, Pitcher TJ. Effects of whaling on the structure of the Southern Ocean food web: insights on the "krill surplus" from ecosystem modelling. PLoS One 2014; 9:e114978. [PMID: 25517505 PMCID: PMC4269391 DOI: 10.1371/journal.pone.0114978] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 11/16/2014] [Indexed: 02/02/2023] Open
Abstract
The aim of this study was to examine the ecological plausibility of the "krill surplus" hypothesis and the effects of whaling on the Southern Ocean food web using mass-balance ecosystem modelling. The depletion trajectory and unexploited biomass of each rorqual population in the Antarctic was reconstructed using yearly catch records and a set of species-specific surplus production models. The resulting estimates of the unexploited biomass of Antarctic rorquals were used to construct an Ecopath model of the Southern Ocean food web existing in 1900. The rorqual depletion trajectory was then used in an Ecosim scenario to drive rorqual biomasses and examine the "krill surplus" phenomenon and whaling effects on the food web in the years 1900-2008. An additional suite of Ecosim scenarios reflecting several hypothetical trends in Southern Ocean primary productivity were employed to examine the effect of bottom-up forcing on the documented krill biomass trend. The output of the Ecosim scenarios indicated that while the "krill surplus" hypothesis is a plausible explanation of the biomass trends observed in some penguin and pinniped species in the mid-20th century, the excess krill biomass was most likely eliminated by a rapid decline in primary productivity in the years 1975-1995. Our findings suggest that changes in physical conditions in the Southern Ocean during this time period could have eliminated the ecological effects of rorqual depletion, although the mechanism responsible is currently unknown. Furthermore, a decline in iron bioavailability due to rorqual depletion may have contributed to the rapid decline in overall Southern Ocean productivity during the last quarter of the 20th century. The results of this study underscore the need for further research on historical changes in the roles of top-down and bottom-up forcing in structuring the Southern Ocean food web.
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Affiliation(s)
- Szymon Surma
- Fisheries Centre, University of British Columbia, Vancouver, BC, Canada
- * E-mail:
| | - Evgeny A. Pakhomov
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Tony J. Pitcher
- Fisheries Centre, University of British Columbia, Vancouver, BC, Canada
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28
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Huang T, Sun L, Wang Y, Emslie SD. Paleodietary changes by penguins and seals in association with Antarctic climate and sea ice extent. CHINESE SCIENCE BULLETIN-CHINESE 2014. [DOI: 10.1007/s11434-014-0300-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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29
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Dugger KM, Ballard G, Ainley DG, Lyver PO, Schine C. Adélie penguins coping with environmental change: results from a natural experiment at the edge of their breeding range. Front Ecol Evol 2014. [DOI: 10.3389/fevo.2014.00068] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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30
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Kuhn C, Ream R, Sterling J, Thomason J, Towell R. Spatial segregation and the influence of habitat on the foraging behavior of northern fur seals (Callorhinus ursinus). CAN J ZOOL 2014. [DOI: 10.1139/cjz-2014-0087] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Central place foraging by colonial breeders can lead to depleted prey resources around breeding areas. Segregation of foraging areas both within and between large colonies may act as a mechanism to reduce competition for prey resulting in increased foraging success. We reassessed horizontal (spatial) foraging habitat segregation for northern fur seals (Callorhinus ursinus (L., 1758)) within and between colonies on the Pribilof Islands, Alaska (St. Paul and St. George islands), after the population declined by approximately 40%. Additionally, we examined vertical habitat segregation, where foraging ranges overlapped, and describe the influence of different foraging habitats on northern fur seal dive behavior. Spatial habitat segregation in northern fur seal foraging areas occurred between islands but was variable within islands, which is similar to the pattern previously described. There was no evidence for vertical habitat segregation when fur seals from different rookeries on St. George Island used the same foraging area. Additionally, fur seals from St. Paul Island rookeries that foraged in similar habitats showed fewer differences in dive behavior, indicating that foraging habitat plays a significant role in shaping dive behavior. The use of multiple foraging strategies within the Pribilof Island fur seal population could indicate that a complex management and conservation strategy may be necessary to stop the continuing decline of this population.
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Affiliation(s)
- C.E. Kuhn
- National Marine Mammal Laboratory, Alaska Fisheries Science Center – National Marine Fisheries Service – NOAA, 7600 Sand Point Way NE, Seattle, WA 98115, USA
| | - R.R. Ream
- National Marine Mammal Laboratory, Alaska Fisheries Science Center – National Marine Fisheries Service – NOAA, 7600 Sand Point Way NE, Seattle, WA 98115, USA
| | - J.T. Sterling
- National Marine Mammal Laboratory, Alaska Fisheries Science Center – National Marine Fisheries Service – NOAA, 7600 Sand Point Way NE, Seattle, WA 98115, USA
| | - J.R. Thomason
- National Marine Mammal Laboratory, Alaska Fisheries Science Center – National Marine Fisheries Service – NOAA, 7600 Sand Point Way NE, Seattle, WA 98115, USA
| | - R.G. Towell
- National Marine Mammal Laboratory, Alaska Fisheries Science Center – National Marine Fisheries Service – NOAA, 7600 Sand Point Way NE, Seattle, WA 98115, USA
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31
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Climate change, pink salmon, and the nexus between bottom-up and top-down forcing in the subarctic Pacific Ocean and Bering Sea. Proc Natl Acad Sci U S A 2014; 111:E1880-8. [PMID: 24706809 DOI: 10.1073/pnas.1319089111] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Climate change in the last century was associated with spectacular growth of many wild Pacific salmon stocks in the North Pacific Ocean and Bering Sea, apparently through bottom-up forcing linking meteorology to ocean physics, water temperature, and plankton production. One species in particular, pink salmon, became so numerous by the 1990s that they began to dominate other species of salmon for prey resources and to exert top-down control in the open ocean ecosystem. Information from long-term monitoring of seabirds in the Aleutian Islands and Bering Sea reveals that the sphere of influence of pink salmon is much larger than previously known. Seabirds, pink salmon, other species of salmon, and by extension other higher-order predators, are tightly linked ecologically and must be included in international management and conservation policies for sustaining all species that compete for common, finite resource pools. These data further emphasize that the unique 2-y cycle in abundance of pink salmon drives interannual shifts between two alternate states of a complex marine ecosystem.
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Trends in the breeding population of Adélie penguins in the Ross Sea, 1981-2012: a coincidence of climate and resource extraction effects. PLoS One 2014; 9:e91188. [PMID: 24621601 PMCID: PMC3951313 DOI: 10.1371/journal.pone.0091188] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 02/10/2014] [Indexed: 12/03/2022] Open
Abstract
Measurements of the size of Adélie penguin (Pygoscelis adeliae) colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981–2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation) reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28%) of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island). The southern population had a negative per capita growth rate of −0.019 during 1981–2000, followed by a positive per capita growth rate of 0.067 for 2001–2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni), may explain the sharp increasing trend evident since then.
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Lescroël A, Ballard G, Grémillet D, Authier M, Ainley DG. Antarctic climate change: extreme events disrupt plastic phenotypic response in Adélie penguins. PLoS One 2014; 9:e85291. [PMID: 24489657 PMCID: PMC3906005 DOI: 10.1371/journal.pone.0085291] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Accepted: 12/04/2013] [Indexed: 02/01/2023] Open
Abstract
In the context of predicted alteration of sea ice cover and increased frequency of extreme events, it is especially timely to investigate plasticity within Antarctic species responding to a key environmental aspect of their ecology: sea ice variability. Using 13 years of longitudinal data, we investigated the effect of sea ice concentration (SIC) on the foraging efficiency of Adélie penguins (Pygoscelis adeliae) breeding in the Ross Sea. A 'natural experiment' brought by the exceptional presence of giant icebergs during 5 consecutive years provided unprecedented habitat variation for testing the effects of extreme events on the relationship between SIC and foraging efficiency in this sea-ice dependent species. Significant levels of phenotypic plasticity were evident in response to changes in SIC in normal environmental conditions. Maximum foraging efficiency occurred at relatively low SIC, peaking at 6.1% and decreasing with higher SIC. The 'natural experiment' uncoupled efficiency levels from SIC variations. Our study suggests that lower summer SIC than currently observed would benefit the foraging performance of Adélie penguins in their southernmost breeding area. Importantly, it also provides evidence that extreme climatic events can disrupt response plasticity in a wild seabird population. This questions the predictive power of relationships built on past observations, when not only the average climatic conditions are changing but the frequency of extreme climatic anomalies is also on the rise.
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Affiliation(s)
- Amélie Lescroël
- Biodiversité et gestion des territoires, URU 420, Université de Rennes 1, Rennes, France
- Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, UMR 5175, Montpellier, France
| | - Grant Ballard
- Point Blue Conservation Science, Petaluma, California, United States of America
| | - David Grémillet
- Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, UMR 5175, Montpellier, France
- Percy FitzPatrick Institute and DST/NRF Excellence Centre, University of Cape Town, Rondebosch, South Africa
| | - Matthieu Authier
- Centre d'Ecologie Fonctionnelle et Evolutive, CNRS, UMR 5175, Montpellier, France
| | - David G. Ainley
- H.T. Harvey & Associates, Los Gatos, California, United States of America
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34
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Smith WO, Ainley DG, Arrigo KR, Dinniman MS. The oceanography and ecology of the Ross Sea. ANNUAL REVIEW OF MARINE SCIENCE 2013; 6:469-487. [PMID: 23987914 DOI: 10.1146/annurev-marine-010213-135114] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The continental shelf of the Ross Sea exhibits substantial variations in physical forcing, ice cover, and biological processes on a variety of time and space scales. Its circulation is characterized by advective inputs from the east and exchanges with off-shelf regions via the troughs along the northern portions. Phytoplankton biomass is greater there than anywhere else in the Antarctic, although nitrate is rarely reduced to levels below 10 μmol L(-1). Overall growth is regulated by irradiance (via ice at the surface and by the depths of the mixed layers) and iron concentrations. Apex predators reach exceptional abundances, and the world's largest colonies of Adélie and emperor penguins are found there. Krill are represented by two species (Euphausia superba near the shelf break and Euphausia crystallorophias throughout the continental shelf region). Equally important and poorly known is the Antarctic silverfish (Pleuragramma antarcticum), which is also consumed by most upper-trophic-level predators. Future changes in the Ross Sea environment will have profound and unpredictable effects on the food web.
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Affiliation(s)
- Walker O Smith
- Virginia Institute of Marine Science, College of William & Mary, Gloucester Point, Virginia 23062;
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Birth‐year and current‐year influences on survival and recruitment rates of female Weddell seals. POPUL ECOL 2013. [DOI: 10.1007/s10144-013-0379-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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McKinstry CAE, Westgate AJ, Koopman HN. Annual variation in the nutritional value of Stage V Calanus finmarchicus: implications for right whales and other copepod predators. ENDANGER SPECIES RES 2013. [DOI: 10.3354/esr00497] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Jeglinski JWE, Goetz KT, Werner C, Costa DP, Trillmich F. Same size - same niche? Foraging niche separation between sympatric juvenile Galapagos sea lions and adult Galapagos fur seals. J Anim Ecol 2013; 82:694-706. [DOI: 10.1111/1365-2656.12019] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 10/08/2012] [Indexed: 11/28/2022]
Affiliation(s)
| | - Kimberley T. Goetz
- Department of Ecology and Evolutionary Biology; University of California; Santa Cruz; CA; USA
| | | | - Daniel P. Costa
- Department of Ecology and Evolutionary Biology; University of California; Santa Cruz; CA; USA
| | - Fritz Trillmich
- Department of Behavioural Biology; University of Bielefeld; Bielefeld; Germany
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Lynch HJ, Naveen R, Trathan PN, Fagan WF. Spatially integrated assessment reveals widespread changes in penguin populations on the Antarctic Peninsula. Ecology 2012; 93:1367-77. [PMID: 22834377 DOI: 10.1890/11-1588.1] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
As important marine mesopredators and sensitive indicators of Antarctic ecosystem change, penguins have been a major focus of long-term biological research in the Antarctic. However, the vast majority of such studies have been constrained by logistics and relate mostly to the temporal dynamics of individual breeding populations from which regional trends have been inferred, often without regard for the complex spatial heterogeneity of population processes and the underlying environmental conditions. Integrating diverse census data from 70 breeding sites across 31 years in a robust, hierarchical analysis, we find that trends from intensely studied populations may poorly reflect regional dynamics and confuse interpretation of environmental drivers. Results from integrated analyses confirm that Pygoscelis adeliae (Adélie Penguins) are decreasing at almost all locations on the Antarctic Peninsula. Results also resolve previously contradictory studies and unambiguously establish that P. antarctica (Chinstrap Penguins), thought to benefit from decreasing sea ice, are instead declining regionally. In contrast, another open-water species, P. papua (Gentoo Penguin), is increasing in abundance and expanding southward. These disparate population trends accord with recent mechanistic hypotheses of biological change in the Southern Ocean and highlight limitations of the influential but oversimplified "sea ice" hypothesis. Aggregating population data at the regional scale also allows us to quantify rates of regional population change in a way not previously possible.
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Affiliation(s)
- Heather J Lynch
- 640 Life Sciences Building, Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York 11794, USA.
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Lewison R, Oro D, Godley B, Underhill L, Bearhop S, Wilson RP, Ainley D, Arcos JM, Boersma PD, Borboroglu PG, Boulinier T, Frederiksen M, Genovart M, González-Solís J, Green JA, Grémillet D, Hamer KC, Hilton GM, Hyrenbach KD, Martínez-Abraín A, Montevecchi WA, Phillips RA, Ryan PG, Sagar P, Sydeman WJ, Wanless S, Watanuki Y, Weimerskirch H, Yorio P. Research priorities for seabirds: improving conservation and management in the 21st century. ENDANGER SPECIES RES 2012. [DOI: 10.3354/esr00419] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Garrott RA, Rotella JJ, Siniff DB, Parkinson CL, Stauffer GE. Environmental variation and cohort effects in an Antarctic predator. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.19673.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Toge K, Yamashita R, Kazama K, Fukuwaka M, Yamamura O, Watanuki Y. The relationship between pink salmon biomass and the body condition of short-tailed shearwaters in the Bering Sea: can fish compete with seabirds? Proc Biol Sci 2011; 278:2584-90. [PMID: 21270043 DOI: 10.1098/rspb.2010.2345] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Seabirds and large fishes are important top predators in marine ecosystems, but few studies have explored the potential for competition between these groups. This study investigates the relationship between an observed biennial change of pink salmon (Oncorhynchus gorbuscha) biomass in the central Bering Sea (23 times greater in odd-numbered than in even-numbered years) and the body condition and diet of the short-tailed shearwater (Puffinus tenuirostris) that spends the post-breeding season there. Samples were collected with research gill nets over seven summers. Both species feed on krill, small fishes and squid. Although the mean pink salmon catch per unit effort (in mass) over the study region was not related significantly with shearwater's stomach content mass or prey composition, the pink salmon biomass showed a negative and significant relationship with the shearwater's body mass and liver mass (proxies of energy reserve). We interpret these results as evidence that fishes can negatively affect mean prey intake of seabirds if they feed on a shared prey in the pelagic ecosystem.
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Affiliation(s)
- Kanako Toge
- Graduate School of Fisheries Sciences, Hokkaido University, 3-1-1 Minato-cho, Hakodate 041-8611, Japan
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Ainley DG, Jongsomjit D, Ballard G, Thiele D, Fraser WR, Tynan CT. Modeling the relationship of Antarctic minke whales to major ocean boundaries. Polar Biol 2011. [DOI: 10.1007/s00300-011-1075-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Ainley DG, Ballard G. Non-consumptive factors affecting foraging patterns in Antarctic penguins: a review and synthesis. Polar Biol 2011. [DOI: 10.1007/s00300-011-1042-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Daily activity and minimum food requirements during winter for gentoo penguins (Pygoscelis papua) in the South Shetland Islands, Antarctica. Polar Biol 2011. [DOI: 10.1007/s00300-011-1018-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Lescroël A, Ballard G, Toniolo V, Barton KJ, Wilson PR, Lyver PO, Ainley DG. Working less to gain more: when breeding quality relates to foraging efficiency. Ecology 2010; 91:2044-55. [PMID: 20715627 DOI: 10.1890/09-0766.1] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In animal populations, a minority of individuals consistently achieves the highest breeding success and therefore contributes the most recruits to future generations. On average, foraging performance is important in determining breeding success at the population level, but evidence is scarce to show that more successful breeders (better breeders) forage differently than less successful ones (poorer breeders). To test this hypothesis, we used a 10-year, three-colony, individual-based longitudinal data set on breeding success and foraging parameters of a long-lived bird, the Adélie Penguin, Pygoscelis adeliae. Better breeders foraged more efficiently than poorer breeders under harsh environmental conditions and when offspring needs were higher, therefore gaining higher net energy profit to be allocated to reproduction and survival. These results imply that adverse "extrinsic" conditions might select breeding individuals on the basis of their foraging ability. Adélie Penguins show sufficient phenotypic plasticity that at least a portion of the population is capable of surviving and successfully reproducing despite extreme variability in their physical and biological environment, variability that is likely to be associated with climate change and, ultimately, with the species' evolution. This study is the first to demonstrate the importance of "extrinsic" conditions (in terms of environmental conditions and offspring needs) on the relationship between foraging behavior and individual quality.
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Ballard G, Toniolo V, Ainley DG, Parkinson CL, Arrigo KR, Trathan PN. Responding to climate change: Adélie Penguins confront astronomical and ocean boundaries. Ecology 2010; 91:2056-69. [DOI: 10.1890/09-0688.1] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Cockrem JF, Barrett DP, Candy EJ, Potter MA. Corticosterone responses in birds: individual variation and repeatability in Adelie penguins (Pygoscelisadeliae) and other species, and the use of power analysis to determine sample sizes. Gen Comp Endocrinol 2009; 163:158-68. [PMID: 19351536 DOI: 10.1016/j.ygcen.2009.03.029] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 03/31/2009] [Accepted: 03/31/2009] [Indexed: 11/30/2022]
Abstract
Plasma corticosterone concentrations increase when birds experience a stressor, and in this study we quantified variation in corticosterone responses for the first time in a species of free-living bird. Adelie penguins (Pygoscelisadeliae) nesting at Cape Bird on Ross Island in Antarctica were sampled on three occasions. Penguins with relatively low or high corticosterone responses on the first occasion had consistently low or high responses, as previously found for great tits and chickens. A model for birds is proposed in which birds with low corticosterone responses and proactive personalities are likely to be more successful (have greater fitness) in constant or predictable conditions, whilst birds with reactive personalities and high corticosterone responses will be more successful in changing or unpredictable conditions. There is thus no linear relationship between the size of a corticosterone response and fitness. Whilst the absolute magnitude of corticosterone responses varies markedly across species of birds, coefficients of variation are similar. Individual corticosterone responses are generally repeatable, with significant statistical repeatabilities for 30 min corticosterone concentrations and integrated corticosterone concentrations in the Adelie penguin, great tit and chicken. Coefficients of variation in corticosterone responses between birds and power analyses were used to provide a rule of thumb for determining differences between groups of birds in mean corticosterone concentrations to enable statistical analyses to have acceptable levels of statistical power for given sample sizes. It is suggested that power analyses and this rule of thumb be adopted in future investigations of corticosterone responses in birds.
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Affiliation(s)
- John F Cockrem
- Conservation Endocrinology Research Group, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand.
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Abstract
There is growing recognition of the important roles played by predators in regulating ecosystems and sustaining biodiversity. Much attention has focused on the consequences of predator-regulation of herbivore populations, and associated trophic cascades. However apex predators may also control smaller 'mesopredators' through intraguild interactions. Removal of apex predators can result in changes to intraguild interactions and outbreaks of mesopredators ('mesopredator release'), leading in turn to increased predation on smaller prey. Here we provide a review and synthesis of studies of predator interactions, mesopredator release and their impacts on biodiversity. Mesopredator suppression by apex predators is widespread geographically and taxonomically. Apex predators suppress mesopredators both by killing them, or instilling fear, which motivates changes in behaviour and habitat use that limit mesopredator distribution and abundance. Changes in the abundance of apex predators may have disproportionate (up to fourfold) effects on mesopredator abundance. Outcomes of interactions between predators may however vary with resource availability, habitat complexity and the complexity of predator communities. There is potential for the restoration of apex predators to have benefits for biodiversity conservation through moderation of the impacts of mesopredators on their prey, but this requires a whole-ecosystem view to avoid unforeseen negative effects. 'Nothing has changed since I began. My eye has permitted no change. I am going to keep things like this.' From 'Hawk Roosting', by Ted Hughes.
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Affiliation(s)
- Euan G Ritchie
- School of Marine and Tropical Biology, James Cook University, Townsville, Queensland 4811, Australia.
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