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LaRue M, Iles D, Labrousse S, Fretwell P, Ortega D, Devane E, Horstmann I, Viollat L, Foster-Dyer R, Le Bohec C, Zitterbart D, Houstin A, Richter S, Winterl A, Wienecke B, Salas L, Nixon M, Barbraud C, Kooyman G, Ponganis P, Ainley D, Trathan P, Jenouvrier S. Advances in remote sensing of emperor penguins: first multi-year time series documenting trends in the global population. Proc Biol Sci 2024; 291:20232067. [PMID: 38471550 PMCID: PMC10932703 DOI: 10.1098/rspb.2023.2067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 02/15/2024] [Indexed: 03/14/2024] Open
Abstract
Like many polar animals, emperor penguin populations are challenging to monitor because of the species' life history and remoteness. Consequently, it has been difficult to establish its global status, a subject important to resolve as polar environments change. To advance our understanding of emperor penguins, we combined remote sensing, validation surveys and using Bayesian modelling, we estimated a comprehensive population trajectory over a recent 10-year period, encompassing the entirety of the species' range. Reported as indices of abundance, our study indicates with 81% probability that there were fewer adult emperor penguins in 2018 than in 2009, with a posterior median decrease of 9.6% (95% credible interval (CI) -26.4% to +9.4%). The global population trend was -1.3% per year over this period (95% CI = -3.3% to +1.0%) and declines probably occurred in four of eight fast ice regions, irrespective of habitat conditions. Thus far, explanations have yet to be identified regarding trends, especially as we observed an apparent population uptick toward the end of time series. Our work potentially establishes a framework for monitoring other Antarctic coastal species detectable by satellite, while promoting a need for research to better understand factors driving biotic changes in the Southern Ocean ecosystem.
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Affiliation(s)
- Michelle LaRue
- Department of Earth and Environmental Science, University of Minnesota, Minneapolis, MN, USA
- School of Earth and Environment, University of Canterbury, Christchurch, New Zealand
| | - David Iles
- Canadian Wildlife Service, Environment and Climate Change Canada, Ottawa, Canada
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Sara Labrousse
- Department of Earth and Environmental Science, University of Minnesota, Minneapolis, MN, USA
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Sorbonne Université, LOCEAN-IPSL, UMR 7159, 75005, Paris, France
| | | | - David Ortega
- Department of Earth and Environmental Science, University of Minnesota, Minneapolis, MN, USA
| | - Eileen Devane
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | | | - Lise Viollat
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Rose Foster-Dyer
- School of Earth and Environment, University of Canterbury, Christchurch, New Zealand
| | - Céline Le Bohec
- Centre National de la Recherche Scientifique, Université de Strasbourg, IPHC UMR 7178, Strasbourg, France
- Département de Biologie Polaire, Centre Scientifique de Monaco, Monaco City, Monaco
| | - Daniel Zitterbart
- Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Aymeric Houstin
- Centre National de la Recherche Scientifique, Université de Strasbourg, IPHC UMR 7178, Strasbourg, France
- Département de Biologie Polaire, Centre Scientifique de Monaco, Monaco City, Monaco
- Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Sebastian Richter
- Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Alexander Winterl
- Department of Physics, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Barbara Wienecke
- Department of Climate Change, Energy, the Environment and Water, Australian Antarctic Division, Hobart, Australia
| | - Leo Salas
- Point Blue Conservation Science, Petaluma, CA, USA
| | - Monique Nixon
- School of Earth and Environment, University of Canterbury, Christchurch, New Zealand
| | - Christophe Barbraud
- Centre d'Etudes Biologiques de Chizé, UMR7372 Centre National de la Recherche Scientifique – La Rochelle Université, 79360 Villiers en Bois, France
| | | | - Paul Ponganis
- Scripps Institution of Oceanography, La Jolla, CA, USA
| | | | - Philip Trathan
- British Antarctic Survey, Cambridge, UK
- Ocean and Earth Science, National Oceanography Centre, University of Southampton, University Road, Southampton SO17 1BJ, UK
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Menze S, Zitterbart D, Biuw M, Boebel O. Estimating the spatial distribution of vocalizing animals from ambient sound spectra using widely spaced recorder arrays and inverse modelling. J Acoust Soc Am 2019; 146:4699. [PMID: 31893742 DOI: 10.1121/1.5139406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 11/18/2019] [Indexed: 06/10/2023]
Abstract
The sound energy from marine mammal populations vocalizing over extended periods of time adds up to quasi-continuous "choruses," which create characteristic peaks in marine sound spectra. An approach to estimate animal distribution is presented, which uses chorus recordings from very sparse unsynchronized arrays in ocean areas that are too large or remote to survey with traditional methods. To solve this under-determined inverse problem, simulated annealing is used to estimate the distribution of vocalizing animals on a geodesic grid. This includes calculating a transmission loss (TL) matrix, which connects all grid nodes and recorders. Geometrical spreading and the ray trace model BELLHOP [Porter (1987). J. Acoust. Soc. Am. 82(4), 1349-1359] were implemented. The robustness of the proposed method was tested with simulated marine mammal distributions in the Atlantic sector of the Southern Ocean using both drifting acoustic recorders [Argo (2018). SEANOE] and a moored array as acoustic receivers. The results show that inversion accuracy mainly depends on the number and location of the recorders, and can be predicted using the entropy and range of the estimated source distributions. Tests with different TL models indicated that inversion accuracy is affected only slightly by inevitable inaccuracies in TL models. The presented method could also be applied to bird, crustacean, and insect choruses.
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Affiliation(s)
- Sebastian Menze
- Oceanography and Climate Group, Institute of Marine Research, P. O. Box 1870, Nordnes, Bergen, Norway
| | - Daniel Zitterbart
- Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, 266 Woods Hole Road, Woods Hole, Massachusetts 02543-1050, USA
| | - Martin Biuw
- Marine Mammal Group, Institute of Marine Research, Tromsø, Norway
| | - Olaf Boebel
- Ocean Acoustics Group, Alfred-Wegener-Institute, Helmholtz-Center for Polar and Marine Research, Klussmannstrasse 3d, 27570 Bremerhaven, Germany
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Gerum R, Richter S, Fabry B, Le Bohec C, Bonadonna F, Nesterova A, Zitterbart D. Structural organisation and dynamics in king penguin colonies. J Phys D Appl Phys 2018; 51:164004. [PMID: 30319146 PMCID: PMC6181452 DOI: 10.1088/1361-6463/aab46b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
During breeding, king penguins do not build nests, however they show strong territorial behaviour and keep a pecking distance to neighbouring penguins. Penguin positions in breeding colonies are highly stable over weeks and appear regularly spaced, but thus far no quantitative analysis of the structural order inside a colony has been performed. In this study, we use the radial distribution function to analyse the spatial coordinates of penguin positions. Coordinates are obtained from aerial images of two colonies that were observed for several years. Our data demonstrate that the structural order in king penguin colonies resembles a 2-dimensional liquid of particles with a Lennard-Jones-type interaction potential. We verify this using a molecular dynamics simulation with thermally driven particles, whereby temperature corresponds to penguin movements, the energy well depth e of the attractive potential corresponds to the strength of the colony-forming behaviour, and the repulsive zone corresponds to the pecking radius. We can recapitulate the liquid disorder of the colony, as measured by the radial distribution function, when the particles have a temperature of several (1.4-10) ε/k B and a normally distributed repulsive radius. To account for the observation that penguin positions are stable over the entire breeding period, we hypothesize that the liquid disorder is quenched during the colony formation process. Quenching requires the temperature to fall considerably below 1 ε/k B, which corresponds to a glass transition, or the repulsion radius to exceed the distance between neighbouring penguins, which corresponds to a jamming transition. Video recordings of a breeding colony together with simulations suggest that quenching is achieved by a behavioural motility arrest akin to a glass transition. We suggest that a liquid disordered colony structure provides an ideal compromise between high density and high flexibility to respond to external disturbances that require a repositioning of penguins.
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Affiliation(s)
- Richard Gerum
- Department of Physics, University of Erlangen-Nürnberg, Germany
| | | | - Ben Fabry
- Department of Physics, University of Erlangen-Nürnberg, Germany
| | - Céline Le Bohec
- Université de Strasbourg, CNRS, IPHC, UMR 7178, Strasbourg, France
- Centre Scientifique de Monaco, Département de Biologie Polaire, Monaco, Principality of Monaco
- LIA 647 BioSensib (CSM-CNRS-Unistra), Monaco, Principality of Monaco
| | - Francesco Bonadonna
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier, France
| | - Anna Nesterova
- Université de Strasbourg, CNRS, IPHC, UMR 7178, Strasbourg, France
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, Montpellier, France
| | - Daniel Zitterbart
- Department of Physics, University of Erlangen-Nürnberg, Germany
- Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, USA
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