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Sontag PT, Godfrey LV, Fraser WR, Hinke JT, Reinfelder JR. Influence of migration range and foraging ecology on mercury accumulation in Southern Ocean penguins. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 951:175154. [PMID: 39153634 DOI: 10.1016/j.scitotenv.2024.175154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 07/26/2024] [Accepted: 07/28/2024] [Indexed: 08/19/2024]
Abstract
In order to evaluate mercury (Hg) accumulation patterns in Southern Ocean penguins, we measured Hg concentrations and carbon (δ13C) and nitrogen (δ15N) stable isotope ratios in body feathers of adult Adélie (Pygoscelis adeliae), gentoo (Pygoscelis papua), and chinstrap (Pygoscelis antarctica) penguins living near Anvers Island, West Antarctic Peninsula (WAP) collected in the 2010/2011 austral summer. With these and data from Pygoscelis and other penguin genera (Eudyptes and Aptenodytes) throughout the Southern Ocean, we modelled Hg variation using δ13C and δ15N values. Mean concentrations of Hg in feathers of Adélie (0.09 ± 0.05 μg g-1) and gentoo (0.16 ± 0.08 μg g-1) penguins from Anvers Island were among the lowest ever reported for the Southern Ocean. However, Hg concentrations in chinstrap penguins (0.80 ± 0.20 μg g-1), which undertake relatively broad longitudinal winter migrations north of expanding sea ice, were significantly higher (P < 0.001) than those in gentoo or Adélie penguins. δ13C and δ15N values for feathers from all three Anvers Island populations were also the lowest among those previously reported for Southern Ocean penguins foraging within Antarctic and subantarctic waters. These observations, along with size distributions of WAP krill, suggest foraging during non-breeding seasons as a primary contributor to higher Hg accumulation in chinstraps relative to other sympatric Pygoscelis along the WAP. δ13C values for all Southern Ocean penguin populations, alone best explained feather Hg concentrations among possible generalized linear models (GLMs) for populations grouped by either breeding site (AICc = 36.9, wi = 0.0590) or Antarctic Frontal Zone (AICc = 36.9, wi = 0.0537). Although Hg feather concentrations can vary locally by species, there was an insignificant species-level effect (wi < 0.001) across the full latitudinal range examined. Therefore, feeding ecology at breeding locations, as tracked by δ13C, control Hg accumulation in penguin populations across the Southern Ocean.
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Affiliation(s)
- Philip T Sontag
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA.
| | - Linda V Godfrey
- Department of Earth and Planetary Sciences, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854, USA
| | | | - Jefferson T Hinke
- Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 8901 La Jolla Shores Drive, La Jolla, CA 92037, USA
| | - John R Reinfelder
- Department of Environmental Sciences, Rutgers University, 14 College Farm Road, New Brunswick, NJ 08901, USA
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2
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Allison AZT, Conway CJ, Goldberg AR. Weather influences survival probability in two coexisting mammals directly and indirectly via competitive asymmetry. Ecology 2024; 105:e4229. [PMID: 38071700 DOI: 10.1002/ecy.4229] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 05/27/2023] [Accepted: 10/19/2023] [Indexed: 12/22/2023]
Abstract
Ecologists have studied the role of interspecific competition in structuring ecological communities for decades. Differential weather effects on animal competitors may be a particularly important factor contributing to the outcome of competitive interactions, though few studies have tested this hypothesis in free-ranging animals. Specifically, weather might influence competitive dynamics by altering competitor densities and/or per-capita competitive effects on demographic vital rates. We used a 9-year data set of marked individuals to test for direct and interactive effects of weather and competitor density on survival probability in two coexisting mammalian congeners: Columbian ground squirrels (Urocitellus columbianus) and northern Idaho ground squirrels (Urocitellus brunneus). Ambient temperature and precipitation influenced survival probability in both species, but the effects of weather differed between the two species. Moreover, density of the larger Columbian ground squirrel negatively impacted survival probability in the smaller northern Idaho ground squirrel (but not vice versa), and the strength of the negative effect was exacerbated by precipitation. That is, cooler, wetter conditions benefited the larger competitor to the detriment of the smaller species. Our results suggest weather-driven environmental variation influences the competitive equilibrium between ecologically similar mammals of differential body size. Whether future climate change leads to the competitive exclusion of either species will likely depend on the mechanism(s) explaining the coexistence of these competing species. Divergent body size and, hence, differences in thermal tolerance and giving up densities offer potential explanations for the weather-dependent competitive asymmetry we documented, especially if the larger species competitively excludes the smaller species from habitat patches of shared preference via interference.
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Affiliation(s)
- Austin Z T Allison
- Department of Fish and Wildlife Sciences, Idaho Cooperative Fish and Wildlife Research Unit, University of Idaho, Moscow, Idaho, USA
| | - Courtney J Conway
- U.S. Geological Survey, Idaho Cooperative Fish and Wildlife Research Unit, University of Idaho, Moscow, Idaho, USA
| | - Amanda R Goldberg
- Department of Fish and Wildlife Sciences, Idaho Cooperative Fish and Wildlife Research Unit, University of Idaho, Moscow, Idaho, USA
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3
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Antarctic krill (Euphausia superba) distributions, aggregation structures, and predator interactions in Bransfield Strait. Polar Biol 2023. [DOI: 10.1007/s00300-023-03113-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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4
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Bird Communities in a Changing World: The Role of Interspecific Competition. DIVERSITY 2022. [DOI: 10.3390/d14100857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Significant changes in the environment have the potential to affect bird species abundance and distribution, both directly, through a modification of the landscape, habitats, and climate, and indirectly, through a modification of biotic interactions such as competitive interactions. Predicting and mitigating the consequences of global change thus requires not only a sound understanding of the role played by biotic interactions in current ecosystems, but also the recognition and study of the complex and intricate effects that result from the perturbation of these ecosystems. In this review, we emphasize the role of interspecific competition in bird communities by focusing on three main predictions derived from theoretical and empirical considerations. We provide numerous examples of population decline and displacement that appeared to be, at least in part, driven by competition, and were amplified by environmental changes associated with human activities. Beyond a shift in relative species abundance, we show that interspecific competition may have a negative impact on species richness, ecosystem services, and endangered species. Despite these findings, we argue that, in general, the role played by interspecific competition in current communities remains poorly understood due to methodological issues and the complexity of natural communities. Predicting the consequences of global change in these communities is further complicated by uncertainty regarding future environmental conditions and the speed and efficacy of plastic and evolutionary responses to fast-changing environments. Possible directions of future research are highlighted.
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Phillips LR, Carroll G, Jonsen I, Harcourt R, Brierley AS, Wilkins A, Cox M. Variability in prey field structure drives inter-annual differences in prey encounter by a marine predator, the little penguin. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220028. [PMID: 36117863 PMCID: PMC9470263 DOI: 10.1098/rsos.220028] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 08/26/2022] [Indexed: 06/15/2023]
Abstract
Understanding how marine predators encounter prey across patchy landscapes remains challenging due to difficulties in measuring the three-dimensional structure of pelagic prey fields at scales relevant to animal movement. We measured at-sea behaviour of a central-place forager, the little penguin (Eudyptula minor), over 5 years (2015-2019) using GPS and dive loggers. We made contemporaneous measurements of the prey field within the penguins' foraging range via boat-based acoustic surveys. We developed a prey encounter index by comparing estimates of acoustic prey density encountered along actual penguin tracks to those encountered along simulated penguin tracks with the same characteristics as real tracks but that moved randomly through the prey field. In most years, penguin tracks encountered prey better than simulated random movements greater than 99% of the time, and penguin dive depths matched peaks in the vertical distribution of prey. However, when prey was unusually sparse and/or deep, penguins had worse than random prey encounter indices, exhibited dives that mismatched depth of maximum prey density, and females had abnormally low body mass (5.3% lower than average). Reductions in prey encounters owing to decreases in the density or accessibility of prey may ultimately lead to reduced fitness and population declines in central-place foraging marine predators.
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Affiliation(s)
| | - Gemma Carroll
- School of Aquatic and Fisheries Sciences, University of Washington, WA, USA
- Resource Ecology and Fisheries Management Division, NOAA Alaska Fisheries Science Center, Seattle, WA USA
| | - Ian Jonsen
- Macquarie University, Sydney, NSW, Australia
| | | | - Andrew S. Brierley
- Pelagic Ecology Research Group, Scottish Oceans Institute, Gatty Marine Laboratory, School of Biology, University of St. Andrews, St Andrews, Scotland KY16 8LB, UK
| | - Adam Wilkins
- Field Friendly, 203 Channel Highway, Kingston, Tasmania 7050, Australia
| | - Martin Cox
- Pelagic Ecology Research Group, Scottish Oceans Institute, Gatty Marine Laboratory, School of Biology, University of St. Andrews, St Andrews, Scotland KY16 8LB, UK
- Australian Antarctic Division, 203 Channel Highway, Kingston, Tasmania 7050, Australia
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6
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Molecular dietary analysis of Adélie (Pygoscelis adeliae) and Gentoo (Pygoscelis papua) penguins breeding sympatrically on Antarctic Ardley Island using fecal DNA. Polar Biol 2022. [DOI: 10.1007/s00300-022-03051-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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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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Cimino MA, Patterson‐Fraser DL, Stammerjohn S, Fraser WR. The interaction between island geomorphology and environmental parameters drives Adélie penguin breeding phenology on neighboring islands near Palmer Station, Antarctica. Ecol Evol 2019; 9:9334-9349. [PMID: 31463025 PMCID: PMC6706194 DOI: 10.1002/ece3.5481] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 06/25/2019] [Accepted: 07/03/2019] [Indexed: 11/06/2022] Open
Abstract
Despite many studies on Adélie penguin breeding phenology, understanding the drivers of clutch initiation dates (CIDs, egg 1 lay date) is limited or lacks consensus. Here, we investigated Adélie penguin CIDs over 25 years (1991-2016) on two neighboring islands, Torgersen and Humble (<1 km apart), in a rapidly warming region near Palmer Station, Antarctica. We found that sea ice was the primary large-scale driver of CIDs and precipitation was a secondary small-scale driver that fine-tunes CID to island-specific nesting habitat geomorphology. In general, CIDs were earlier (later) when the spring sea ice retreat was earlier (later) and when the preceding annual ice season was shorter (longer). Island-specific effects related to precipitation and island geomorphology caused greater snow accumulation and delayed CIDs by ~2 days on Torgersen compared to Humble Island. When CIDs on the islands were similar, conditions were mild with less snow across breeding sites. At Torgersen Island, the negative relationship between CID and breeding success highlights detrimental effects of delayed breeding and/or snow on penguin fitness. Past phenological studies reported a relationship between air temperature and CID, assumed to be related to precipitation, but we found air temperature was more highly correlated to sea ice, revealing a misinterpretation of temperature effects. Finally, contrasting trends in CIDs based on temporal shifts in regional sea ice patterns revealed trends toward earlier CIDs (4-6 day advance) from 1979 to 2009 as the annual ice season shortened, and later CIDs (7-10 day delay) from 2010 to 2016 as the annual ice season lengthened. Adélie penguins tracked environmental conditions with flexible breeding phenology, but their life history remains vulnerable to subpolar weather conditions that can delay CIDs and decrease breeding success, especially on landscapes where geomorphology facilitates snow accumulation.
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Affiliation(s)
- Megan A. Cimino
- Institute of Marine SciencesUniversity of California, Santa CruzSanta CruzCAUSA
| | | | - Sharon Stammerjohn
- Institute of Arctic and Alpine ResearchUniversity of ColoradoBoulderCOUSA
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9
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Oliver MJ, Kohut JT, Bernard K, Fraser W, Winsor P, Statscewich H, Fredj E, Cimino M, Patterson-Fraser D, Carvalho F. Central place foragers select ocean surface convergent features despite differing foraging strategies. Sci Rep 2019; 9:157. [PMID: 30655549 PMCID: PMC6336854 DOI: 10.1038/s41598-018-35901-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 11/09/2018] [Indexed: 11/09/2022] Open
Abstract
Discovering the predictors of foraging locations can be challenging, and is often the critical missing piece for interpreting the ecological significance of observed movement patterns of predators. This is especially true in dynamic coastal marine systems, where planktonic food resources are diffuse and must be either physically or biologically concentrated to support upper trophic levels. In the Western Antarctic Peninsula, recent climate change has created new foraging sympatry between Adélie (Pygoscelis adeliae) and gentoo (P. papua) penguins in a known biological hotspot near Palmer Deep canyon. We used this recent sympatry as an opportunity to investigate how dynamic local oceanographic features affect aspects of the foraging ecology of these two species. Simulated particle trajectories from measured surface currents were used to investigate the co-occurrence of convergent ocean features and penguin foraging locations. Adélie penguin diving activity was restricted to the upper mixed layer, while gentoo penguins often foraged much deeper than the mixed layer, suggesting that Adélie penguins may be more responsive to dynamic surface convergent features compared to gentoo penguins. We found that, despite large differences in diving and foraging behavior, both shallow-diving Adélie and deeper-diving gentoo penguins strongly selected for surface convergent features. Furthermore, there was no difference in selectivity for shallow- versus deep-diving gentoo penguins. Our results suggest that these two mesopredators are selecting surface convergent features, however, how these surface signals are related to subsurface prey fields is unknown.
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Affiliation(s)
- Matthew J Oliver
- University of Delaware, College of Earth, Ocean and Environment, 700 Pilottown Road, Lewes, DE, 19958, USA
| | - Josh T Kohut
- Rutgers, The State University of New Jersey, Department of Marine and Coastal Sciences, 71 Dudley Road, New Brunswick, NJ, 08901, USA.
| | - Kim Bernard
- Oregon State University, College of Earth, Ocean, and Atmospheric Sciences, 104 CEOAS Admin Bldg, Corvallis, OR, 97330, USA
| | - William Fraser
- Polar Oceans Research Group, P.O. Box 368, Sheridan, MT, 59749, USA
| | - Peter Winsor
- University of Alaska, Fairbanks, College of Fisheries and Ocean Sciences, 905 Koyukuk Dr. Suite 245 O'Neill Bldg., Fairbanks, AK, 99775-7220, USA
| | - Hank Statscewich
- University of Alaska, Fairbanks, College of Fisheries and Ocean Sciences, 905 Koyukuk Dr. Suite 245 O'Neill Bldg., Fairbanks, AK, 99775-7220, USA
| | - Erick Fredj
- The Jerusalem College of Technology, Computer Science Department, 21 Havaad Haleumi St., P.O. Box 16031, Jerusalem, 91160, Israel
| | - Megan Cimino
- Scripps Institution of Oceanography, University of California, San Diego, Coastal Observing R&D Center, 9500 Gilman Drive #0214, La Jolla, CA, 92093, USA
| | | | - Filipa Carvalho
- National Oceanography Centre, European Way, Southampton, SO14 3ZH, United Kingdom
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10
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Clewlow HL, Takahashi A, Watanabe S, Votier SC, Downie R, Ratcliffe N. Niche partitioning of sympatric penguins by leapfrog foraging appears to be resilient to climate change. J Anim Ecol 2018; 88:223-235. [PMID: 30378103 PMCID: PMC7379715 DOI: 10.1111/1365-2656.12919] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 10/04/2018] [Indexed: 11/29/2022]
Abstract
Interspecific competition can drive niche partitioning along multidimensional axes, including allochrony. Competitor matching will arise where the phenology of sympatric species with similar ecological requirements responds to climate change at different rates such that allochrony is reduced. Our study quantifies the degree of niche segregation in foraging areas and depths that arises from allochrony in sympatric Adélie and chinstrap penguins and explores its resilience to climate change. Three-dimensional tracking data were sampled during all stages of the breeding season and were used to parameterise a behaviour-based model that quantified spatial overlap of foraging areas under different scenarios of allochrony. The foraging ranges of the two species were similar within breeding stages, but differences in their foraging ranges between stages, combined with the observed allochrony of 28 days, resulted in them leapfrogging each other through the breeding season such that they were exploiting different foraging locations on the same calendar dates. Allochrony reduced spatial overlap in the peripheral utilisation distribution of the two species by 54.0% over the entire breeding season, compared to a scenario where the two species bred synchronously. Analysis of long-term phenology data revealed that both species advanced their laying dates in relation to October air temperatures at the same rate, preserving allochrony and niche partitioning. However, if allochrony is reduced by just a single day, the spatial overlap of the core utilisation distribution increased by an average of 2.1% over the entire breeding season. Niche partitioning between the two species by allochrony appears to be resilient to climate change and so competitor matching cannot be implicated in the observed population declines of the two penguin species across the Western Antarctic Peninsula.
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Affiliation(s)
- Harriet L Clewlow
- British Antarctic Survey, Cambridge, UK.,Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | | | | | - Stephen C Votier
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | - Rod Downie
- WWF-UK, The Living Planet Centre, Woking, UK
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11
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Pickett EP, Fraser WR, Patterson‐Fraser DL, Cimino MA, Torres LG, Friedlaender AS. Spatial niche partitioning may promote coexistence of Pygoscelis penguins as climate-induced sympatry occurs. Ecol Evol 2018; 8:9764-9778. [PMID: 30386573 PMCID: PMC6202752 DOI: 10.1002/ece3.4445] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 07/03/2018] [Accepted: 07/06/2018] [Indexed: 11/09/2022] Open
Abstract
Climate-induced range overlap can result in novel interactions between similar species and potentially lead to competitive exclusion. The West Antarctic Peninsula (WAP) is one of the most rapidly warming regions on Earth and is experiencing a poleward climate migration from a polar to subpolar environment. This has resulted in a range expansion of the ice-intolerant gentoo penguins (Pygoscelis papua) and a coincident decrease in ice-obligate Adélie penguins (P. adeliae) near Palmer Station, Anvers Island, WAP. Ecologically similar species that share a limited prey resource must occupy disparate foraging niches in order to co-exist. Therefore, we determined the extent of foraging and dietary niche segregation between Adélie and gentoo penguins during the austral breeding season near Palmer Station. This research was conducted across six breeding seasons, from 2009 to 2014, which allowed us to investigate niche overlap in the context of interannual resource variability. Using biotelemetry and diet sampling, we found substantial overlap in the diets of Adélie and gentoo penguins, who primarily consumed Antarctic krill (Euphausia superba); however, our results showed that Adélie and gentoo penguins partitioned this shared prey resource through horizontal segregation of their core foraging areas. We did not find evidence that Antarctic krill were a limiting resource during the breeding season or that climate-induced sympatry of Adélie and gentoo penguins resulted in competition for prey or caused the subsequent differing population trajectories. This apparent absence of resource competition between Adélie and gentoo penguins throughout this study implies that current population trends in this region are governed by other biological and physical factors. Our results highlight the importance of understanding the mechanistic processes that influence top predator populations in the context of climate-driven ecosystem shifts.
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Affiliation(s)
- Erin P. Pickett
- Department of Fisheries and WildlifeMarine Mammal InstituteOregon State UniversityNewportOregon
| | | | | | - Megan A. Cimino
- Scripps Institution of OceanographyUniversity of CaliforniaSan DiegoCalifornia
| | - Leigh G. Torres
- Department of Fisheries and WildlifeMarine Mammal InstituteOregon State UniversityNewportOregon
| | - Ari S. Friedlaender
- Department of Fisheries and WildlifeMarine Mammal InstituteOregon State UniversityNewportOregon
- Institute for Marine ScienceUniversity of California Santa CruzSanta CruzCalifornia
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12
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Handley JM, Thiebault A, Stanworth A, Schutt D, Pistorius P. Behaviourally mediated predation avoidance in penguin prey: in situ evidence from animal-borne camera loggers. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171449. [PMID: 30224976 PMCID: PMC6124084 DOI: 10.1098/rsos.171449] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2017] [Accepted: 07/19/2018] [Indexed: 06/08/2023]
Abstract
Predator dietary studies often assume that diet is reflective of the diversity and relative abundance of their prey. This interpretation ignores species-specific behavioural adaptations in prey that could influence prey capture. Here, we develop and describe a scalable biologging protocol, using animal-borne camera loggers, to elucidate the factors influencing prey capture by a seabird, the gentoo penguin (Pygoscelis papua). From the video evidence, we show, to our knowledge for the first time, that aggressive behavioural defence mechanisms by prey can deter prey capture by a seabird. Furthermore, we provide evidence demonstrating that these birds, which were observed hunting solitarily, target prey when they are most discernible. Specifically, birds targeted prey primarily while ascending and when prey were not tightly clustered. In conclusion, we show that prey behaviour can significantly influence trophic coupling in marine systems because despite prey being present, it is not always targeted. Thus, these predator-prey relationships should be accounted for in studies using marine top predators as samplers of mid- to lower trophic-level species.
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Affiliation(s)
- Jonathan M. Handley
- DST/NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, Department of Zoology, Nelson Mandela University, South Campus, Port Elizabeth 6031, South Africa
| | - Andréa Thiebault
- DST/NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, Department of Zoology, Nelson Mandela University, South Campus, Port Elizabeth 6031, South Africa
| | - Andrew Stanworth
- Falklands Conservation, PO Box 26, Stanley FIQQ 1ZZ, Falkland Islands
| | - David Schutt
- Department of Integrative Biology, University of Colorado Denver, PO Box 173364, Denver, CO 80217, USA
| | - Pierre Pistorius
- DST/NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, Department of Zoology, Nelson Mandela University, South Campus, Port Elizabeth 6031, South Africa
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13
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Seasonal prey switching in non-breeding gentoo penguins related to a wintertime environmental anomaly around South Georgia. Polar Biol 2018. [DOI: 10.1007/s00300-018-2372-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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14
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Kohut JT, Winsor P, Statscewich H, Oliver MJ, Fredj E, Couto N, Bernard K, Fraser W. Variability in summer surface residence time within a West Antarctic Peninsula biological hotspot. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2017.0165. [PMID: 29760110 PMCID: PMC5954466 DOI: 10.1098/rsta.2017.0165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/05/2018] [Indexed: 05/30/2023]
Abstract
Palmer Deep canyon along the central West Antarctic Peninsula is known to have higher phytoplankton biomass than the surrounding non-canyon regions, but the circulation mechanisms that transport and locally concentrate phytoplankton and Antarctic krill, potentially increasing prey availability to upper-trophic-level predators such as penguins and cetaceans, are currently unknown. We deployed a three-site high-frequency radar network that provided hourly surface circulation maps over the Palmer Deep hotspot. A series of particle release experiments were used to estimate surface residence time and connectivity across the canyon. The majority of residence times fell between 1.0 and 3.5 days, with a mean of 2 days and a maximum of 5 days. We found a highly significant negative relationship between wind speed and residence time. Our residence time analysis indicates that the elevated phytoplankton biomass over the central canyon is transported into and out of the hotspot on time scales much shorter than the observed phytoplankton growth rate, suggesting that the canyon may not act as an incubator of phytoplankton productivity as previously suggested. It may instead serve more as a conveyor belt of phytoplankton biomass produced elsewhere, continually replenishing the phytoplankton biomass for the local Antarctic krill community, which in turn supports numerous top predators.This article is part of the theme issue 'The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change'.
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Affiliation(s)
- Josh T Kohut
- Department of Marine and Coastal Sciences, Rutgers, The State University of New Jersey, 71 Dudley Road, New Brunswick, NJ 08901, USA
| | - Peter Winsor
- College of Fisheries and Ocean Sciences, University of Alaska, Fairbanks, 2150 Koyukuk Dr., Suite 245 O'Neill Bldg., Fairbanks, AK 99775-7220, USA
| | - Hank Statscewich
- College of Fisheries and Ocean Sciences, University of Alaska, Fairbanks, 2150 Koyukuk Dr., Suite 245 O'Neill Bldg., Fairbanks, AK 99775-7220, USA
| | - Matthew J Oliver
- College of Earth, Ocean and Environment, University of Delaware, 700 Pilottown Road, Lewes, DE 19958, USA
| | - Erick Fredj
- Computer Science Department, The Jerusalem College of Technology, 21 Havaad Haleumi St., PO Box 16031, Jerusalem 91160, Israel
| | - Nicole Couto
- Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive #0213, La Jolla, CA 92093, USA
| | - Kim Bernard
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, 104 CEOAS Admin Bldg, Corvallis, OR 97330, USA
| | - William Fraser
- Polar Oceans Research Group, PO Box 368, Sheridan, MT 59749, USA
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Tarroux A, Lydersen C, Trathan PN, Kovacs KM. Temporal variation in trophic relationships among three congeneric penguin species breeding in sympatry. Ecol Evol 2018; 8:3660-3674. [PMID: 29686847 PMCID: PMC5901183 DOI: 10.1002/ece3.3937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 01/12/2018] [Accepted: 01/27/2018] [Indexed: 11/08/2022] Open
Abstract
Penguins are a monophyletic group in which many species are found breeding sympatrically, raising questions regarding how these species coexist successfully. Here, the isotopic niche of three sympatric pygoscelid penguin species was investigated at Powell Island, South Orkney Islands, during two breeding seasons (austral summers 2013–2014 and 2015–2016). Measurements of carbon (δ13C) and nitrogen (δ15N) stable isotope ratios were obtained from blood (adults) or feather (chicks) samples collected from Adélie Pygoscelis adeliae, chinstrap P. antarctica, and gentoo P. papua penguins. Isotopic niche regions (a proxy for the realized trophic niches) were computed to provide estimates of the trophic niche width of the studied species during the breeding season. The isotopic niche regions of adults of all three species were similar, but gentoo chicks had noticeably wider isotopic niches than the chicks of the other two species. Moderate to strong overlap in isotopic niche among species was found during each breeding season and for both age groups, suggesting that the potential for competition for shared food sources was similar during the two study years, although the actual level of competition could not be determined owing to the lack of data on resource abundance. Clear interannual shifts in isotopic niche were seen in all three species, though of lower amplitude for adult chinstrap penguins. These shifts were due to variation in carbon, but not nitrogen, isotopic ratios, which could indicate either a change in isotopic signature of their prey or a switch to an alternative food web. The main conclusions of this study are that (1) there is a partial overlap in the isotopic niches of these three congeneric species and that (2) they responded similarly to changes that likely occurred at the base of their food chain between the 2 years of the study.
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Affiliation(s)
- Arnaud Tarroux
- Norwegian Polar Institute Fram Centre Tromsø Norway.,Norwegian Institute for Nature Research Fram Centre Tromsø Norway
| | | | | | - Kit M Kovacs
- Norwegian Polar Institute Fram Centre Tromsø Norway
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16
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Isotopic niches of sympatric Gentoo and Chinstrap Penguins: evidence of competition for Antarctic krill? Polar Biol 2018. [DOI: 10.1007/s00300-018-2306-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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17
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Xavier JC, Trathan PN, Ceia FR, Tarling GA, Adlard S, Fox D, Edwards EWJ, Vieira RP, Medeiros R, De Broyer C, Cherel Y. Sexual and individual foraging segregation in Gentoo penguins Pygoscelis papua from the Southern Ocean during an abnormal winter. PLoS One 2017; 12:e0174850. [PMID: 28362847 PMCID: PMC5376302 DOI: 10.1371/journal.pone.0174850] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 03/16/2017] [Indexed: 01/30/2023] Open
Abstract
Knowledge about sexual segregation and gender-specific, or indeed individual specialization, in marine organisms has improved considerably in the past decade. In this context, we tested the "Intersexual Competition Hypothesis" for penguins by investigating the feeding ecology of Gentoo penguins during their austral winter non-breeding season. We considered this during unusual environmental conditions (i.e. the year 2009 had observations of high sea surface and air temperatures) in comparison with the long term average at Bird Island, South Georgia. Through conventional (i.e. stomach contents) and stable isotopic values from red blood cells, plasma and feathers of both male and female Gentoo penguins, we showed that there were significant differences between sexes, with males feeding mainly on fish (54% by mass) followed by crustaceans (38%) whereas females fed mainly on crustaceans (89% by mass) followed by fish (4%). Themisto gaudichaudii was the most important crustacean prey for males (64% by mass; 82% by number; 53% by frequency of occurrence) and females (63% by mass; 77% by number; 89% by frequency of occurrence), contrasting with all previous studies that found Antarctic krill Euphausia superba were generally the main prey. Stable isotopic data showed that, in terms of habitat use (based on δ 13C), there were significant differences in short-term carbon signatures between males and females (based on plasma and red blood cells), suggesting that both sexes explored different habitats, with females exploring more offshore pelagic waters and males feeding more in coastal benthic waters. Based on δ 15N, males fed on significantly higher trophic level than females (based on plasma and red blood cells), in agreement with our diet results., Thus, Gentoo penguins behave in a similar manner to other non-breeding penguins species (e.g. king, macaroni and rockhopper penguins), albeit at a smaller spatial scale (as they do not disperse as these other penguins do), in that they have a wider habitat and trophic niche during the Antarctic Winter (in comparison to Summer). We also detected individual specialization in feeding/trophic levels for each gender, with certain males feeding mainly on fish and certain females mainly on crustaceans, which may be driven the prevailing environmental conditions that lead individuals to search for alternative prey, and cause sexual diet segregation. Our results provide further information to help improve understanding about sexual segregation and individual specialization of marine organisms, while contributing valuable information on the winter diet for Antarctic monitoring programs and for modelling Antarctic marine food webs.
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Affiliation(s)
- José C Xavier
- Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.,British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, UK
| | - Philip N Trathan
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, UK
| | - Filipe R Ceia
- Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Geraint A Tarling
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, UK
| | - Stacey Adlard
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, UK
| | - Derren Fox
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, UK
| | - Ewan W J Edwards
- British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, UK
| | - Rui P Vieira
- Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Renata Medeiros
- Cardiff University, Cardiff School of Biosciences, Sir Martin Evans Building, Cardiff, United Kingdom
| | - Claude De Broyer
- Royal Belgian Institute of Natural Sciences, OD Taxonomy and Phylogeny, Rue Vautier 29, Bruxelles, Belgium
| | - Yves Cherel
- Centre d´Etudes Biologiques de Chizé, UPR 7372 du CNRS-Université de La Rochelle, Villiers-en-Bois, France
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18
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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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19
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Ancel A, Cristofari R, Trathan PN, Gilbert C, Fretwell PT, Beaulieu M. Looking for new emperor penguin colonies? Filling the gaps. Glob Ecol Conserv 2017. [DOI: 10.1016/j.gecco.2017.01.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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20
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Cimino MA, Lynch HJ, Saba VS, Oliver MJ. Projected asymmetric response of Adélie penguins to Antarctic climate change. Sci Rep 2016; 6:28785. [PMID: 27352849 PMCID: PMC4926113 DOI: 10.1038/srep28785] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 06/08/2016] [Indexed: 11/15/2022] Open
Abstract
The contribution of climate change to shifts in a species’ geographic distribution is a critical and often unresolved ecological question. Climate change in Antarctica is asymmetric, with cooling in parts of the continent and warming along the West Antarctic Peninsula (WAP). The Adélie penguin (Pygoscelis adeliae) is a circumpolar meso-predator exposed to the full range of Antarctic climate and is undergoing dramatic population shifts coincident with climate change. We used true presence-absence data on Adélie penguin breeding colonies to estimate past and future changes in habitat suitability during the chick-rearing period based on historic satellite observations and future climate model projections. During the contemporary period, declining Adélie penguin populations experienced more years with warm sea surface temperature compared to populations that are increasing. Based on this relationship, we project that one-third of current Adélie penguin colonies, representing ~20% of their current population, may be in decline by 2060. However, climate model projections suggest refugia may exist in continental Antarctica beyond 2099, buffering species-wide declines. Climate change impacts on penguins in the Antarctic will likely be highly site specific based on regional climate trends, and a southward contraction in the range of Adélie penguins is likely over the next century.
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Affiliation(s)
- Megan A Cimino
- College of Earth Ocean and Environment, University of Delaware, 700 Pilottown Rd., Lewes, DE 19958, United States
| | - Heather J Lynch
- Stony Brook University, 113 Life Sciences Bldg., Stony Brook, NY 11794, United States
| | - Vincent S Saba
- NOAA National Marine Fisheries Service, Northeast Fisheries Science Center, c/o Geophysical Fluid Dynamics Laboratory, Princeton University Forrestal Campus, 201 Forrestal Road, Princeton, NJ 08540, United States
| | - Matthew J Oliver
- College of Earth Ocean and Environment, University of Delaware, 700 Pilottown Rd., Lewes, DE 19958, United States
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