Trathan
Phil N.
Trathan
Phil N.
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ArticleFull circumpolar migration ensures evolutionary unity in the Emperor penguin(Nature Publishing Group, 2016-06-14) Cristofari, Robin ; Bertorelle, Giorgio ; Ancel, André ; Benazzo, Andrea ; Le Maho, Yvon ; Ponganis, Paul J. ; Stenseth, Nils Christian ; Trathan, Phil N. ; Whittington, Jason D. ; Zanetti, Enrico ; Zitterbart, Daniel ; Le Bohec, Céline ; Trucchi, EmilianoDefining reliable demographic models is essential to understand the threats of ongoing environmental change. Yet, in the most remote and threatened areas, models are often based on the survey of a single population, assuming stationarity and independence in population responses. This is the case for the Emperor penguin Aptenodytes forsteri, a flagship Antarctic species that may be at high risk continent-wide before 2100. Here, using genome-wide data from the whole Antarctic continent, we reveal that this top-predator is organized as one single global population with a shared demography since the late Quaternary. We refute the view of the local population as a relevant demographic unit, and highlight that (i) robust extinction risk estimations are only possible by including dispersal rates and (ii) colony-scaled population size is rather indicative of local stochastic events, whereas the species’ response to global environmental change is likely to follow a shared evolutionary trajectory.
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ArticleThe call of the emperor penguin: legal responses to species threatened by climate change(Wiley, 2021-08-03) Jenouvrier, Stephanie ; Che-Castaldo, Judy ; Wolf, Shaye ; Holland, Marika M. ; Labrousse, Sara ; LaRue, Michelle ; Wienecke, Barbara ; Fretwell, Peter T. ; Barbraud, Christophe ; Greenwald, Noah ; Stroeve, Julienne ; Trathan, Phil N.Species extinction risk is accelerating due to anthropogenic climate change, making it urgent to protect vulnerable species through legal frameworks in order to facilitate conservation actions that help mitigate risk. Here, we discuss fundamental concepts for assessing climate change risks to species using the example of the emperor penguin (Aptenodytes forsteri), currently being considered for protection under the US Endangered Species Act (ESA). This species forms colonies on Antarctic sea ice, which is projected to significantly decline due to ongoing greenhouse gas (GHG) emissions. We project the dynamics of all known emperor penguin colonies under different GHG emission scenarios using a climate-dependent meta-population model including the effects of extreme climate events based on the observational satellite record of colonies. Assessments for listing species under the ESA require information about how species resiliency, redundancy and representation (3Rs) will be affected by threats within the foreseeable future. Our results show that if sea ice declines at the rate projected by climate models under current energy system trends and policies, the 3Rs would be dramatically reduced and almost all colonies would become quasi-extinct by 2100. We conclude that the species should be listed as threatened under the ESA.
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ArticleThe emperor penguin - vulnerable to projected rates of warming and sea ice loss(Elsevier, 2019-10-08) Trathan, Phil N. ; Wienecke, Barbara ; Barbraud, Christophe ; Jenouvrier, Stephanie ; Kooyman, Gerald L. ; Le Bohec, Céline ; Ainley, David G. ; Ancel, André ; Zitterbart, Daniel ; Chown, Steven L. ; LaRue, Michelle ; Cristofari, Robin ; Younger, Jane ; Clucas, Gemma V. ; Bost, Charles-Andre ; Brown, Jennifer A. ; Gillett, Harriet J. ; Fretwell, Peter T.We argue the need to improve climate change forecasting for ecology, and importantly, how to relate long-term projections to conservation. As an example, we discuss the need for effective management of one species, the emperor penguin, Aptenodytes forsteri. This species is unique amongst birds in that its breeding habit is critically dependent upon seasonal fast ice. Here, we review its vulnerability to ongoing and projected climate change, given that sea ice is susceptible to changes in winds and temperatures. We consider published projections of future emperor penguin population status in response to changing environments. Furthermore, we evaluate the current IUCN Red List status for the species, and recommend that its status be changed to Vulnerable, based on different modelling projections of population decrease of ≥50% over the current century, and the specific traits of the species. We conclude that current conservation measures are inadequate to protect the species under future projected scenarios. Only a reduction in anthropogenic greenhouse gas emissions will reduce threats to the emperor penguin from altered wind regimes, rising temperatures and melting sea ice; until such time, other conservation actions are necessary, including increased spatial protection at breeding sites and foraging locations. The designation of large-scale marine spatial protection across its range would benefit the species, particularly in areas that have a high probability of becoming future climate change refugia. We also recommend that the emperor penguin is listed by the Antarctic Treaty as an Antarctic Specially Protected Species, with development of a species Action Plan.
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ArticleSpectral reflectance of whale skin above the sea surface: a proposed measurement protocol(Wiley Open Access, 2020-03-10) Cubaynes, Hannah C. ; Rees, W. Gareth ; Jackson, Jennifer A. ; Moore, Michael J. ; Sformo, Todd L. ; McLellan, William A. ; Niemeyer, Misty E. ; George, John C. ; van der Hoop, Julie ; Forcada, Jaume ; Trathan, Phil N. ; Fretwell, Peter T.Great whales have been detected using very‐high‐resolution satellite imagery, suggesting this technology could be used to monitor whales in remote areas. However, the application of this method to whale studies is at an early developmental stage and several technical factors need to be addressed, including capacity for species differentiation and the maximum depth of detection in the water column. Both require knowledge of the spectral reflectance of the various whale species just above the sea surface, as when whales bodies break the surface of the water to breath, log or breach, there is, at times, no sea water between the whale's skin and the satellite sensor. Here we tested whether such reflectance could be measured on dead whale tissue. We measured the spectral reflectance of fresh integument collected during the bowhead subsistence harvest, and of thawed integument samples from various species obtained following strandings and stored at −20°C. We show that fresh and thawed samples of whale integument have different spectral properties. The reflectance of fresh samples was higher than the reflectance of thawed samples, as integument appears to darken after death and with time, even under frozen conditions. In this study, we present the first whale reflectance estimates (without the influence of sea water and for dead tissue). These provide a baseline for additional work, needed to advance the use of satellite imagery to monitor whales and facilitate their conservation.
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ArticleQuantifying the causes and consequences of variation in satellite-derived population indices: a case study of emperor penguins(Wiley Open Access, 2021-08-11) Labrousse, Sara ; Iles, David T. ; Viollat, Lise ; Fretwell, Peter T. ; Trathan, Phil N. ; Zitterbart, Daniel ; Jenouvrier, Stephanie ; LaRue, MichelleVery high-resolution satellite (VHR) imagery is a promising tool for estimating the abundance of wildlife populations, especially in remote regions where traditional surveys are limited by logistical challenges. Emperor penguins Aptenodytes forsteri were the first species to have a circumpolar population estimate derived via VHR imagery. Here we address an untested assumption from Fretwell et al. (2012) that a single image of an emperor penguin colony is a reasonable representation of the colony for the year the image was taken. We evaluated satellite-related and environmental variables that might influence the calculated area of penguin pixels to reduce uncertainties in satellite-based estimates of emperor penguin populations in the future. We focused our analysis on multiple VHR images from three representative colonies: Atka Bay, Stancomb-Wills (Weddell Sea sector) and Coulman Island (Ross Sea sector) between September and December during 2011. We replicated methods in Fretwell et al. (2012), which included using supervised classification tools in ArcGIS 10.7 software to calculate area occupied by penguins (hereafter referred to as ‘population indices’) in each image. We found that population indices varied from 2 to nearly 6-fold, suggesting that penguin pixel areas calculated from a single image may not provide a complete understanding of colony size for that year. Thus, we further highlight the important roles of: (i) sun azimuth and elevation through image resolution and (ii) penguin patchiness (aggregated vs. distributed) on the calculated areas. We found an effect of wind and temperature on penguin patchiness. Despite intra-seasonal variability in population indices, simulations indicate that reliable, robust population trends are possible by including satellite-related and environmental covariates and aggregating indices across time and space. Our work provides additional parameters that should be included in future models of population size for emperor penguins.
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ArticleMarine ecosystem assessment for the Southern Ocean: birds and marine mammals in a changing climate(Frontiers Media, 2020-11-04) Bestley, Sophie ; Ropert-Coudert, Yan ; Bengtson Nash, Susan ; Brooks, Cassandra M. ; Cotté, Cédric ; Dewar, Meagan ; Friedlaender, Ari S. ; Jackson, Jennifer A. ; Labrousse, Sara ; Lowther, Andrew D. ; McMahon, Clive R. ; Phillips, Richard A. ; Pistorius, Pierre ; Puskic, Peter S. ; de Almeida Reis, Ana Olívia ; Reisinger, Ryan ; Santos, Mercedes ; Tarszisz, Esther ; Tixier, Paul ; Trathan, Phil N. ; Wege, Mia ; Wienecke, BarbaraThe massive number of seabirds (penguins and procellariiformes) and marine mammals (cetaceans and pinnipeds) – referred to here as top predators – is one of the most iconic components of the Antarctic and Southern Ocean. They play an important role as highly mobile consumers, structuring and connecting pelagic marine food webs and are widely studied relative to other taxa. Many birds and mammals establish dense breeding colonies or use haul-out sites, making them relatively easy to study. Cetaceans, however, spend their lives at sea and thus aspects of their life cycle are more complicated to monitor and study. Nevertheless, they all feed at sea and their reproductive success depends on the food availability in the marine environment, hence they are considered useful indicators of the state of the marine resources. In general, top predators have large body sizes that allow for instrumentation with miniature data-recording or transmitting devices to monitor their activities at sea. Development of scientific techniques to study reproduction and foraging of top predators has led to substantial scientific literature on their population trends, key biological parameters, migratory patterns, foraging and feeding ecology, and linkages with atmospheric or oceanographic dynamics, for a number of species and regions. We briefly summarize the vast literature on Southern Ocean top predators, focusing on the most recent syntheses. We also provide an overview on the key current and emerging pressures faced by these animals as a result of both natural and human causes. We recognize the overarching impact that environmental changes driven by climate change have on the ecology of these species. We also evaluate direct and indirect interactions between marine predators and other factors such as disease, pollution, land disturbance and the increasing pressure from global fisheries in the Southern Ocean. Where possible we consider the data availability for assessing the status and trends for each of these components, their capacity for resilience or recovery, effectiveness of management responses, risk likelihood of key impacts and future outlook.
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ArticleHappy feet in a hostile world? The future of penguins depends on proactive management of current and expected threats.(Frontiers Media, 2019-05-28) Ropert-Coudert, Yan ; Chiaradia, André ; Ainley, David G. ; Barbosa, Andres ; Boersma, P. Dee ; Brasso, Rebecka ; Dewar, Meagan ; Ellenberg, Ursula ; García-Borboroglu, Pablo ; Emmerson, Louise M. ; Hickcox, Rachel ; Jenouvrier, Stephanie ; Kato, Akiko ; McIntosh, Rebecca Ruth ; Lewis, Phoebe ; Ramírez, Francisco ; Ruoppolo, Valeria ; Ryan, Peter G. ; Seddon, Philip J. ; Sherley, Richard Brain ; Vanstreels, Ralph E. T. ; Waller, Lauren J. ; Woehler, Eric ; Trathan, Phil N.Penguins face a wide range of threats. Most observed population changes have been negative and have happened over the last 60 years. Today, populations of 11 penguin species are decreasing. Here we present a review that synthesizes details of threats faced by the world’s 18 species of penguins. We discuss alterations to their environment at both breeding sites on land and at sea where they forage. The major drivers of change appear to be climate, and food web alterations by marine fisheries. In addition, we also consider other critical and/or emerging threats, namely human disturbance near nesting sites, pollution due to oil, plastics and chemicals such as mercury and persistent organic compounds. Finally, we assess the importance of emerging pathogens and diseases on the health of penguins. We suggest that in the context of climate change, habitat degradation, introduced exotic species and resource competition with fisheries, successful conservation outcomes will require new and unprecedented levels of science and advocacy. Successful conservation stories of penguin species across their geographical range have occurred where there has been concerted effort across local, national and international boundaries to implement effective conservation planning.
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ArticleStroke frequency, but not swimming speed, is related to body size in free-ranging seabirds, pinnipeds and cetaceans(Royal Society, 2006-12-05) Sato, Katsufumi ; Watanuki, Yutaka ; Takahashi, Akinori ; Miller, Patrick J. O. ; Tanaka, Hideji ; Kawabe, Ryo ; Ponganis, Paul J. ; Handrich, Yves ; Akamatsu, Tomonari ; Watanabe, Yuuki ; Mitani, Yoko ; Costa, Daniel P. ; Bost, Charles-Andre ; Aoki, Kagari ; Amano, Masao ; Trathan, Phil N. ; Shapiro, Ari D. ; Naito, YasuhikoIt is obvious, at least qualitatively, that small animals move their locomotory apparatus faster than large animals: small insects move their wings invisibly fast, while large birds flap their wings slowly. However, quantitative observations have been difficult to obtain from free-ranging swimming animals. We surveyed the swimming behaviour of animals ranging from 0.5kg seabirds to 30000kg sperm whales using animal-borne accelerometers. Dominant stroke cycle frequencies of swimming specialist seabirds and marine mammals were proportional to mass−0.29 (R2=0.99, n=17 groups), while propulsive swimming speeds of 1–2ms−1 were independent of body size. This scaling relationship, obtained from breath-hold divers expected to swim optimally to conserve oxygen, does not agree with recent theoretical predictions for optimal swimming. Seabirds that use their wings for both swimming and flying stroked at a lower frequency than other swimming specialists of the same size, suggesting a morphological trade-off with wing size and stroke frequency representing a compromise. In contrast, foot-propelled diving birds such as shags had similar stroke frequencies as other swimming specialists. These results suggest that muscle characteristics may constrain swimming during cruising travel, with convergence among diving specialists in the proportions and contraction rates of propulsive muscles.
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ArticleHave whales returned to a historical hotspot of industrial whaling? the pattern of southern right whale Eubalaena australis recovery at South Georgia(Inter Research, 2020-11-05) Jackson, Jennifer A. ; Kennedy, Amy S. ; Moore, Michael J. ; Andriolo, Artur ; Bamford, Connor C. G. ; Calderan, Susannah ; Cheeseman, Ted ; Gittins, George ; Groch, Karina ; Kelly, Natalie ; Leaper, Russell ; Leslie, Matthew S. ; Lurcock, Sarah ; Miller, Brian S. ; Richardson, Jessica ; Rowntree, Victoria ; Smith, Patrick ; Stepien, Emilie N. ; Stowasser, Gabriele ; Trathan, Phil N. ; Vermeulen, Els ; Zerbini, Alexandre N. ; Carroll, EmmaAround 176500 whales were killed in the sub-Antarctic waters off South Georgia (South Atlantic) between 1904 and 1965. In recent decades, whales have once again become summer visitors, with the southern right whale (SRW) the most commonly reported species until 2011. Here, we assess the distribution, temporal pattern, health status and likely prey of SRWs in these waters, combining observations from a summertime vessel-based expedition to South Georgia, stable isotope data collected from SRWs and putative prey and sightings reports collated by the South Georgia Museum. The expedition used directional acoustics and visual surveys to localise whales and collected skin biopsies and photo-IDs. During 76 h of visual observation effort over 19 expedition days, SRWs were encountered 15 times (~31 individuals). Photo-IDs, combined with publicly contributed images from commercial vessels, were reconciled and quality-controlled to form a catalogue of 6 fully (i.e. both sides) identified SRWs and 26 SRWs identified by either left or right sides. No photo-ID matches were found with lower-latitude calving grounds, but 3 whales had gull lesions supporting a direct link with Península Valdés, Argentina. The isotopic position of SRWs in the South Georgia food web suggests feeding on a combination of copepod and krill species. Opportunistic reports of SRW sightings and associated group sizes remain steady over time, while humpback whales provide a strong contrast, with increased sighting rates and group sizes seen since 2013. These data suggest a plateau in SRWs and an increasing humpback whale presence in South Georgia waters following the cessation of whaling.