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Chapman E.W.,Old Dominion University | Hofmann E.E.,Old Dominion University | Patterson D.L.,Polar Oceans Research Group | Fraser W.R.,Polar Oceans Research Group
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2010

Factors that control variability in energy density of Antarctic krill (Euphausia superba) populations, and the consequences of this variability for growth and fledging mass of Adélie penguin (Pygoscelis adeliae) chicks, were investigated using an individual-based energetics model. Lipid content as a function of sex/maturity stage and season was used to calculate the energy density of krill ingested by chicks. Simulations tested the influence of variability in krill size-class distribution, sex-ratio, length-at-maturity, and the timing of spawning on krill population energy density and penguin chick fledging mass. Of the parameters included in simulations, variability in the timing of krill spawning had the greatest influence on predicted Adélie penguin fledging mass, with fledging mass decreasing from 3.30 to 2.92 kg when peak spawning was shifted from early December to early March. Adélie penguin chicks that fledge from colonies along the western Antarctic Peninsula (wAP) and survive to recruit into the breeding population are 0.117 kg heavier than those that do not survive to breed. Thus, it appears that small differences in fledging mass potentially have significant implications for Adélie penguin chick survivorship. Therefore, the timing of krill spawning may have important consequences for Adélie penguins, and other top-predator species, that may time critical activities to coincide with a period of dependable prey availability with maximum energy density. © 2009 Elsevier Ltd.

Chapman E.W.,Old Dominion University | Chapman E.W.,University of New Hampshire | Hofmann E.E.,Old Dominion University | Patterson D.L.,Polar Oceans Research Group | And 2 more authors.
Marine Ecology Progress Series | Year: 2011

An individual-based bioenergetics model that simulates the growth of an Adélie penguin Pygoscelis adeliae chick from hatching to fledging was used to assess marine and terrestrial factors that affect chick growth and fledging mass off the western Antarctic Peninsula. Simulations considered the effects on Adélie penguin fledging mass of (1) modification of chick diet through the addition of Antarctic silverfish Pleuragramma antarcticum to an all-Antarctic krill Euphausia superba diet, (2) reduction of provisioning rate which may occur as a result of an environmental stress such as reduced prey availability, and (3) increased thermoregulatory costs due to wetting of chicks which may result from increased precipitation or snow-melt in colonies. Addition of 17% Antarctic silverfish of Age-Class 3 yr (AC3) to a penguin chick diet composed of Antarctic krill increased chick fledging mass by 5%. Environmental stress that results in >4% reduction in provisioning rate or wetting of just 10% of the chick's surface area decreased fledging mass enough to reduce the chick's probability of successful recruitment. The negative effects of reduced provisioning and wetting on chick growth can be compensated for by inclusion of Antarctic silverfish of AC3 and older in the chick diet. Results provide insight into climate-driven processes that influence chick growth and highlight a need for field research designed to investigate factors that determine the availability of AC3 and older Antarctic silverfish to foraging Adélie penguins and the influence of snowfall on chick wetting, thermoregulation and adult provisioning rate. © 2011 Inter-Research.

Ainley D.,983 University Avenue | Russell J.,University of Arizona | Jenouvrier S.,Woods Hole Oceanographic Institution | Woehler E.,University of Tasmania | And 3 more authors.
Ecological Monographs | Year: 2010

We assess the response of pack ice penguins, Emperor (Aptenodytes forsteri) and Adélie (Pygoscelis adeliae), to habitat variability and, then, by modeling habitat alterations, the qualitative changes to their populations, size and distribution, as Earth's average tropospheric temperature reaches 2°C above preindustrial levels (ca. 1860), the benchmark set by the European Union in efforts to reduce greenhouse gases. First, we assessed models used in the Intergovernmental Panel on Climate Change Fourth Assessment Report (AR4) on penguin performance duplicating existing conditions in the Southern Ocean. We chose four models appropriate for gauging changes to penguin habitat: GFDL-CM2.1, GFDL-CM2.0, MIROC3.2(hi-res), and MRI-CGCM2.3.2a. Second, we analyzed the composited model ENSEMBLE to estimate the point of 2°C warming (2025-2052) and the projected changes to sea ice coverage (extent, persistence, and concentration), sea ice thickness, wind speeds, precipitation, and air temperatures. Third, we considered studies of ancient colonies and sediment cores and some recent modeling, which indicate the (space/time) large/centennialscale penguin response to habitat limits of all ice or no ice. Then we considered results of statistical modeling at the temporal interannual-decadal scale in regard to penguin response over a continuum of rather complex, meso- to large-scale habitat conditions, some of which have opposing and others interacting effects. The ENSEMBLE meso/decadal-scale output projects a marked narrowing of penguins' Zoogeographic range at the 2°C point. Colonies north of 70° S are projected to decrease or disappear: ∼50% of Emperor colonies (40% of breeding population) and ∼75% of Adélie colonies (70% of breeding population), but limited growth might occur south of 73° S. Net change would result largely from positive responses to increase in polynya persistence at high latitudes, overcome by decreases in pack ice cover at lower latitudes and, particularly for Emperors, ice thickness. Adélie Penguins might colonize new breeding habitat where concentrated pack ice diverges and/or disintegrating ice shelves expose coastline. Limiting increase will be decreased persistence of pack ice north of the Antarctic Circle, as this species requires daylight in its wintering areas. Adélies would be affected negatively by increasing snowfall, predicted to increase in certain areas owing to intrusions of warm, moist marine air due to changes in the Polar Jet Stream. © 2010 by the Ecological Society of America.

Schofield O.,Rutgers University | Ducklow H.W.,Ecosystems Center | Martinson D.G.,Columbia University | Meredith M.P.,British Antarctic Survey | And 2 more authors.
Science | Year: 2010

Climate change will alter marine ecosystems; however, the complexity of the food webs, combined with chronic undersampling, constrains efforts to predict their future and to optimally manage and protect marine resources. Sustained observations at the West Antarctic Peninsula show that in this region, rapid environmental change has coincided with shifts in the food web, from its base up to apex predators. New strategies will be required to gain further insight into how the marine climate system has influenced such changes and how it will do so in the future. Robotic networks, satellites, ships, and instruments mounted on animals and ice will collect data needed to improve numerical models that can then be used to study the future of polar ecosystems as climate change progresses. Copyright Science 2010 by the American Association for the Advancement of Science; all rights reserved.

Cimino M.A.,University of Delaware | Fraser W.R.,Polar Oceans Research Group | Irwin A.J.,Mount Allison University | Oliver M.J.,University of Delaware
Global Change Biology | Year: 2013

Pygoscelis penguins are experiencing general population declines in their northernmost range whereas there are reported increases in their southernmost range. These changes are coincident with decadal-scale trends in remote sensed observations of sea ice concentrations (SIC) and sea surface temperatures (SST) during the chick-rearing season (austral summer). Using SIC, SST, and bathymetry, we identified separate chick-rearing niche spaces for the three Pygoscelis penguin species and used a maximum entropy approach (MaxEnt) to spatially and temporally model suitable chick-rearing habitats in the Southern Ocean. For all Pygoscelis penguin species, the MaxEnt models predict significant changes in the locations of suitable chick-rearing habitats over the period of 1982-2010. In general, chick-rearing habitat suitability at specific colony locations agreed with the corresponding increases or decreases in documented population trends over the same time period. These changes were the most pronounced along the West Antarctic Peninsula where there has been a rapid warming event during at least the last 50 years. © 2013 Blackwell Publishing Ltd.

Kahl L.A.,Rutgers University | Schofield O.,Rutgers University | Fraser W.R.,Polar Oceans Research Group
Integrative and Comparative Biology | Year: 2010

Despite their strong dependence on the pelagic environment, seabirds and other top predators in polar marine ecosystems are generally studied during their reproductive phases in terrestrial environments. As a result, a significant portion of their life history is understudied which in turn has led to limited understanding. Recent advances in autonomous underwater vehicle (AUV) technologies have allowed satellite-tagged Adélie penguins to guide AUV surveys of the marine environment at the Palmer Long-Term Ecological Research (LTER) site on the western Antarctic Peninsula. Near real-time data sent via Iridium satellites from the AUVs to a centralized control center thousands of miles away allowed scientists to adapt AUV sampling strategies to meet the changing conditions of the subsurface. Such AUV data revealed the water masses and fine-scale features associated with Adélie penguin foraging trips. During this study, the maximum concentration of chlorophyll was between 30 and 50m deep. Encompassing this peak in the chlorophyll concentration, within the water-column, was a mixture of nutrient-laden Upper Circumpolar Deep (UCDW) and western Antarctic Peninsula winter water (WW). Together, data from the AUV survey and penguin dives reveal that 54 of foraging by Adélie penguins occurs immediately below the chlorophyll maximum. These data demonstrate how bringing together emerging technologies, such as AUVs, with established methods such as the radio-tagging of penguins can provide powerful tools for monitoring and hypothesis testing of previously inaccessible ecological processes. Ocean and atmosphere temperatures are expected to continue increasing along the western Antarctic Peninsula, which will undoubtedly affect regional marine ecosystems. New and emerging technologies such as unmanned underwater vehicles and individually mounted satellite tracking devices will provide the tools critical to documenting and understanding the widespread ecological change expected in polar regions. © The Author 2010. Published oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved.

Ribic C.A.,U.S. Geological Survey | Ainley D.G.,983 University Avenue | Glenn Ford R.,University of California at Santa Cruz | Fraser W.R.,Polar Oceans Research Group | And 2 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2011

Waters off the western Antarctic Peninsula (i.e., the eastern Bellingshausen Sea) are unusually complex owing to the convergence of several major fronts. Determining the relative influence of fronts on occurrence patterns of top-trophic species in that area, therefore, has been challenging. In one of the few ocean-wide seabird data syntheses, in this case for the Southern Ocean, we analyzed ample, previously collected cruise data, Antarctic-wide, to determine seabird species assemblages and quantitative relationships to fronts as a way to provide context to the long-term Palmer LTER and the winter Southern Ocean GLOBEC studies in the eastern Bellingshausen Sea. Fronts investigated during both winter (April-September) and summer (October-March) were the southern boundary of the Antarctic Circumpolar Current (ACC), which separates the High Antarctic from the Low Antarctic water mass, and within which are embedded the marginal ice zone and Antarctic Shelf Break Front; and the Antarctic Polar Front, which separates the Low Antarctic and the Subantarctic water masses. We used clustering to determine species' groupings with water masses, and generalized additive models to relate species' densities, biomass and diversity to distance to respective fronts. Antarctic-wide, in both periods, highest seabird densities and lowest species diversity were found in the High Antarctic water mass. In the eastern Bellingshausen, seabird density in the High Antarctic water mass was lower (as low as half that of winter) than found in other Antarctic regions. During winter, Antarctic-wide, two significant species groups were evident: one dominated by Adélie penguins (. Pygoscelis adeliae) (High Antarctic water mass) and the other by petrels and prions (no differentiation among water masses); in eastern Bellingshausen waters during winter, the one significant species group was composed of species from both Antarctic-wide groups. In summer, Antarctic-wide, a High Antarctic group dominated by Adélie penguins, a Low Antarctic group dominated by petrels, and a Subantarctic group dominated by albatross were evident. In eastern Bellingshausen waters during summer, groups were inconsistent. With regard to frontal features, Antarctic-wide in winter, distance to the ice edge was an important explanatory factor for nine of 14 species, distance to the Antarctic Polar Front for six species and distance to the Shelf Break Front for six species; however, these Antarctic-wide models could not successfully predict spatial relationships of winter seabird density (individual species or total) and biomass in the eastern Bellingshausen. Antarctic-wide in summer, distance to land/Antarctic continent was important for 10 of 18 species, not a surprising result for these summer-time Antarctic breeders, as colonies are associated with ice-free areas of coastal land. Distance to the Shelf Break Front was important for 8 and distance to the southern boundary of the ACC was important for 7 species. These summer models were more successful in predicting eastern Bellingshausen species density and species diversity but failed to predict total seabird density or biomass. Antarctic seabirds appear to respond to fronts in a way similar to that observed along the well-studied upwelling front of the California Current. To understand fully the seabird patterns found in this synthesis, multi-disciplinary at-sea investigations, including a quantified prey field, are needed. © 2011.

Erdmann E.S.,University of Wisconsin - Madison | Ribic C.A.,U.S. Geological Survey | Patterson-Fraser D.L.,Polar Oceans Research Group | Fraser W.R.,Polar Oceans Research Group
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2011

In accord with the hypotheses driving the Southern Ocean Global Ocean Ecosystems Dynamics (SO GLOBEC) program, we tested the hypothesis that the winter foraging ecology of a major top predator in waters off the Western Antarctic Peninsula (WAP), the Adélie penguin (. Pygoscelis adeliae), is constrained by oceanographic features related to the physiography of the region. This hypothesis grew from the supposition that breeding colonies in the WAP during summer are located adjacent to areas of complex bathymetry where circulation and upwelling processes appear to ensure predictable food resources. Therefore, we tested the additional hypothesis that these areas continue to contribute to the foraging strategy of this species throughout the non-breeding winter season. We used satellite telemetry data collected as part of the SO GLOBEC program during the austral winters of 2001 and 2002 to characterize individual penguin foraging locations in relation to bathymetry, sea ice variability within the pack ice, and wind velocity and divergence (as a proxy for potential areas with cracks and leads). We also explored differences between males and females in core foraging area overlap. Ocean depth was the most influential variable in the determination of foraging location, with most birds focusing their effort on shallow (<200. m) waters near land and on mixed-layer (200-500. m) waters near the edge of deep troughs. Within-ice variability and wind (as a proxy for potential areas with cracks and leads) were not found to be influential variables, which is likely because of the low resolution satellite imagery and model outputs that were available. Throughout the study period, all individuals maintained a core foraging area separated from other individuals with very little overlap. However, from a year with light sea ice to one with heavy ice cover (2001-2002), we observed an increase in the overlap of individual female foraging areas with those of other birds, likely due to restricted access to the water column, reduced prey abundance, or higher prey concentration. Male birds maintained separate core foraging areas with the same small amount of overlap, showing no difference in overlap between the years. While complex bathymetry was an important physical variable influencing the Adélie penguin's foraging, the analysis of sea ice data of a higher resolution than was available for this study may help elucidate the role of sea ice in affecting Adélie penguin winter foraging behavior within the pack ice. © 2010 Elsevier Ltd.

Friedlaender A.S.,Duke University | Johnston D.W.,Duke University | Fraser W.R.,Polar Oceans Research Group | Burns J.,University of Alaska Anchorage | And 2 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2011

Adélie penguins (. Pygoscelis adeliae), carabeater seals (. Lobodon carcinophagus), humpback (. Megaptera novaeangliae), and minke whales (. Balaenoptera bonaernsis) are found in the waters surrounding the Western Antarctic Peninsula. Each species relies primarily on Antarctic krill (. Euphausia superba) and has physiological constraints and foraging behaviors that dictate their ecological niches. Understanding the degree of ecological overlap between sympatric krill predators is critical to understanding and predicting the impacts on climate-driven changes to the Antarctic marine ecosystem. To explore ecological relationships amongst sympatric krill predators, we developed ecological niche models using a maximum entropy modeling approach (Maxent) that allows the integration of data collected by a variety of means (e.g. satellite-based locations and visual observations). We created spatially explicit probability distributions for the four krill predators in fall 2001 and 2002 in conjunction with a suite of environmental variables. We find areas within Marguerite Bay with high krill predator occurrence rates or biological hot spots. We find the modeled ecological niches for Adélie penguins and crabeater seals may be affected by their physiological needs to haul-out on substrate. Thus, their distributions may be less dictated by proximity to prey and more so by physical features that over time provide adequate access to prey. Humpback and minke whales, being fully marine and having greater energetic demands, occupy ecological niches more directly proximate to prey. We also find evidence to suggest that the amount of overlap between modeled niches is relatively low, even for species with similar energetic requirements. In a rapidly changing and variable environment, our modeling work shows little indication that krill predators maintain similar ecological niches across years around Marguerite Bay. Given the amount of variability in the marine environment around the Antarctic Peninsula and how this affects the local abundance of prey, there may be consequences for krill predators with historically little niche overlap to increase the potential for interspecific competition for shared prey resources. © 2010 Elsevier Ltd.

Agency: NSF | Branch: Standard Grant | Program: | Phase: ANTARCTIC ORGANISMS & ECOSYST | Award Amount: 333.98K | Year: 2013

The application of innovative ocean observing and animal telemetry technology over Palmer Deep (Western Antarctic Peninsula; WAP) is leading to new understanding, and also to many new questions related to polar ecosystem processes and their control by bio-physical interactions in the polar environment. This multi-platform field study will investigate the impact of coastal physical processes (e.g. tides, currents, upwelling events, sea-ice) on Adélie penguin foraging ecology in the vicinity of Palmer Deep, off Anvers Island, WAP. Guided by real-time surface convergence and divergences based on remotely sensed surface current maps derived from a coastal network of High Frequency Radars (HFRs), a multidisciplinary research team will adaptively sample the distribution of phytoplankton and zooplankton, which influence Adélie penguin foraging ecology, to understand how local oceanographic processes structure the ecosystem.

Core educational objectives of this proposal are to increase awareness and
understanding of (i) global climate change, (ii) the unique WAP ecosystem, (iii) innovative methods and technologies used by the researchers, and (iv) careers in ocean sciences, through interactive interviews with scientists, students, and technicians, during the field work. These activities will be directed towards instructional programming for K-16 students and their teachers. Researchers and educators will conduct formative and summative evaluation to improve the educational program and measure its impacts respectively.

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