Examining natural population growth from near extinction: the case of the Antarctic fur seal at the South Shetlands, Antarctica

Hucke‐Gaete, Rodrigo; Osman, Layla P.; Moreno, Carlos; Torres, Daniel

doi:10.1007/s00300-003-0587-8

Cited by 71 publications

(64 citation statements)

References 22 publications

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“…Concomitantly, increasing temperatures and reductions in sea ice have altered the physical environment necessary to sustain large krill populations (25)(26)(27). We hypothesize that the amount of krill available to penguins has declined because of increased competition for krill from recovering whale and fur seal populations (28)(29)(30)(31)(32) and from bottom-up, climate-driven changes that have altered this ecosystem significantly during the last 2-3 decades (4, 7, 8, 33-36; Fig. 2).…”

Section: Resultsmentioning

confidence: 99%

Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica

Trivelpiece

Hinke

Miller

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

366

432

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The West Antarctic Peninsula (WAP) and adjacent Scotia Sea support abundant wildlife populations, many of which were nearly extirpated by humans. This region is also among the fastestwarming areas on the planet, with 5-6°C increases in mean winter air temperatures and associated decreases in winter sea-ice cover. These biological and physical perturbations have affected the ecosystem profoundly. One hypothesis guiding ecological interpretations of changes in top predator populations in this region, the "sea-ice hypothesis," proposes that reductions in winter sea ice have led directly to declines in "ice-loving" species by decreasing their winter habitat, while populations of "ice-avoiding" species have increased. However, 30 y of field studies and recent surveys of penguins throughout the WAP and Scotia Sea demonstrate this mechanism is not controlling penguin populations; populations of both ice-loving Adélie and ice-avoiding chinstrap penguins have declined significantly. We argue in favor of an alternative, more robust hypothesis that attributes both increases and decreases in penguin populations to changes in the abundance of their main prey, Antarctic krill. Unlike many other predators in this region, Adélie and chinstrap penguins were never directly harvested by man; thus, their population trajectories track the impacts of biological and environmental changes in this ecosystem. Linking trends in penguin abundance with trends in krill biomass explains why populations of Adélie and chinstrap penguins increased after competitors (fur seals, baleen whales, and some fishes) were nearly extirpated in the 19th to mid-20th centuries and currently are decreasing in response to climate change.S ea ice plays a critical role in structuring ecosystem dynamics throughout the West Antarctic Peninsula (WAP) and Scotia Sea, and variations in sea-ice extent are hypothesized to affect penguin populations directly. As seasonal sea-ice extent and duration declines in this region, the Adélie penguin (Pygoscelis adeliae), which favors pack-ice habitat in winter, should decline in population size, whereas the closely related chinstrap penguin (Pygoscelis antarctica), which forages in ice-free water during winter, should increase (1-5). The foundation for this hypothesis is based on a short (7-y) series of simultaneously observed decreases in nesting populations of Adélie penguins and increases in chinstrap penguins following winters with low sea ice in the South Shetland Islands during the 1970s and 1980s (1). However there now is overwhelming evidence that, in contrast to expectations, both Adélie and chinstrap penguin populations are declining throughout the WAP and broader Scotia Sea region. Results and DiscussionAdélie and chinstrap penguin populations have declined more than 50% during the last 30 y at study colonies in the South Shetland Islands (Fig. 1A). Moreover, since 1987, interannual changes in Adélie and chinstrap breeding populations have been positively correlated (Pearson's r = 0.7; P < 0.001; n = 21; Fig. 1B). T...

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Section: Resultsmentioning

confidence: 99%

Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica

Trivelpiece

Hinke

Miller

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

366

432

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“…Over time they then develop foraging stra tegies that are similar to adults (Riotte-Lambert & Weimerskirch 2013, de Grissac et al 2017. Initial reliance on innate cues could potentially be problematic for species that experienced large population declines and extirpation from breeding colonies (Payne 1977, Hucke-Gaete et al 2004, Le Boeuf et al 2011, especially when conservation actions facilitate reintroduction through translocations (Deguchi et al 2012(Deguchi et al , 2014(Deguchi et al , 2017. In addition, the importance of learning migration behavior and foraging area selection are likely key components of how marine predators will cope with climate-driven changes to ecosystems (Hazen et al 2012a).…”

Section: Introductionmentioning

confidence: 99%

Ontogenetic changes in at-sea distributions of immature short-tailed albatrosses Phoebastria albatrus

Orben¹,

O'Connor²,

Suryan³

et al. 2018

Endang. Species. Res.

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“…However, although climate-related population changes are suspected for marine mammals in other Antarctic sectors (e.g. fur and southern elephant seals (Weimerskirch et al 2003;Hucke-Gaete et al 2004;McMahon et al 2005) and minke whales (Branch & Butterworth 2001)), data interpretation is potentially confounded by the fact that many of these species are recovering from massive population declines induced by human harvest. As indicated by Smetacek & Nicol (2005), disentangling the effects of human exploitation, climate change and changing modes of top-down Marine pelagic ecosystems: the WAP H. W. Ducklow et al 87 Phil.…”

Section: Marine Mammalsmentioning

confidence: 99%

Marine pelagic ecosystems: the West Antarctic Peninsula

Ducklow

Baker

Martinson

et al. 2006

Phil. Trans. R. Soc. B

558

569

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The marine ecosystem of the West Antarctic Peninsula (WAP) extends from the Bellingshausen Sea to the northern tip of the peninsula and from the mostly glaciated coast across the continental shelf to the shelf break in the west. The glacially sculpted coastline along the peninsula is highly convoluted and characterized by deep embayments that are often interconnected by channels that facilitate transport of heat and nutrients into the shelf domain. The ecosystem is divided into three subregions, the continental slope, shelf and coastal regions, each with unique ocean dynamics, water mass and biological distributions. The WAP shelf lies within the Antarctic Sea Ice Zone (SIZ) and like other SIZs, the WAP system is very productive, supporting large stocks of marine mammals, birds and the Antarctic krill, Euphausia superba. Ecosystem dynamics is dominated by the seasonal and interannual variation in sea ice extent and retreat. The Antarctic Peninsula is one among the most rapidly warming regions on Earth, having experienced a 28C increase in the annual mean temperature and a 68C rise in the mean winter temperature since 1950. Delivery of heat from the Antarctic Circumpolar Current has increased significantly in the past decade, sufficient to drive to a 0.68C warming of the upper 300 m of shelf water. In the past 50 years and continuing in the twenty-first century, the warm, moist maritime climate of the northern WAP has been migrating south, displacing the once dominant cold, dry continental Antarctic climate and causing multi-level responses in the marine ecosystem. Ecosystem responses to the regional warming include increased heat transport, decreased sea ice extent and duration, local declines in icedependent Adélie penguins, increase in ice-tolerant gentoo and chinstrap penguins, alterations in phytoplankton and zooplankton community composition and changes in krill recruitment, abundance and availability to predators. The climate/ecological gradients extending along the WAP and the presence of monitoring systems, field stations and long-term research programmes make the region an invaluable observatory of climate change and marine ecosystem response.

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Examining natural population growth from near extinction: the case of the Antarctic fur seal at the South Shetlands, Antarctica

Cited by 71 publications

References 22 publications

Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica

Variability in krill biomass links harvesting and climate warming to penguin population changes in Antarctica

Ontogenetic changes in at-sea distributions of immature short-tailed albatrosses Phoebastria albatrus

Marine pelagic ecosystems: the West Antarctic Peninsula

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