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Hoekendijk JPA, Grundlehner A, Brasseur S, Kellenberger B, Tuia D, Aarts G. Stay close, but not too close: aerial image analysis reveals patterns of social distancing in seal colonies. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230269. [PMID: 37564067 PMCID: PMC10410205 DOI: 10.1098/rsos.230269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 05/31/2023] [Indexed: 08/12/2023]
Abstract
Many species aggregate in dense colonies. Species-specific spatial patterns provide clues about how colonies are shaped by various (a)biotic factors, including predation, temperature regulation or disease transmission. Using aerial imagery, we examined these patterns in colonies on land of two sympatric seal species: the harbour seal and grey seal. Results show that the density of grey seals on land is twice as high as that of harbour seals. Furthermore, the nearest neighbour distance (NND) of harbour seals (median = 1.06 m) is significantly larger than that of grey seals (median = 0.53 m). Avoidance at small distances (i.e. social distancing) was supported by spatial simulation: when the observed seal locations were shuffled slightly, the frequency of the smallest NNDs (0-25 cm) increased, while the most frequently observed NNDs decreased. As harbour seals are more prone to infectious diseases, we hypothesize that the larger NNDs might be a behavioural response to reduce pathogen transmission. The approach presented here can potentially be used as a practical tool to differentiate between harbour and grey seals in remote sensing applications, particularly in low to medium resolution imagery (e.g. satellite imagery), where morphological characteristics alone are insufficient to differentiate between species.
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Affiliation(s)
- J. P. A. Hoekendijk
- NIOZ Royal Netherlands Institute for Sea Research, 1790AB Den Burg, The Netherlands
- Wageningen University and Research, 6708PB Wageningen, The Netherlands
| | - A. Grundlehner
- Wageningen University and Research, 6708PB Wageningen, The Netherlands
- Wageningen Marine Research, Wageningen University and Research, 1781AG Den Helder, The Netherlands
| | - S. Brasseur
- NIOZ Royal Netherlands Institute for Sea Research, 1790AB Den Burg, The Netherlands
- Wageningen Marine Research, Wageningen University and Research, 1781AG Den Helder, The Netherlands
| | - B. Kellenberger
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA
| | - D. Tuia
- Ecole Polytechnique Fédérale de Lausanne (EPFL), 1950 Sion, Switzerland
| | - G. Aarts
- NIOZ Royal Netherlands Institute for Sea Research, 1790AB Den Burg, The Netherlands
- Wageningen University and Research, 6708PB Wageningen, The Netherlands
- Wageningen Marine Research, Wageningen University and Research, 1781AG Den Helder, The Netherlands
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2
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van Neer A, Nachtsheim D, Siebert U, Taupp T. Movements and spatial usage of harbour seals in the Elbe estuary in Germany. Sci Rep 2023; 13:6630. [PMID: 37095305 PMCID: PMC10125962 DOI: 10.1038/s41598-023-33594-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 04/15/2023] [Indexed: 04/26/2023] Open
Abstract
Harbour seals are top predators in the North Sea and regarded as sentinels for ecosystem health. A few hundred also occur in adjacent estuaries, such as the Elbe estuary, Germany. However, only little is known about how these animals use this dynamic tidally influenced habitat, which has been under high anthropogenic pressure for decades. In this context, nine harbour seals (Phoca vitulina) from the Elbe estuary were equipped with biotelemetry devices to track their movements over multiple months. Harbour seal movements were characterised by short trips (trip length outside pupping season for females: 9.0 ± 1.12 km, males: 7.0 ± 1.24 km) as well as small home ranges (median 50% home range for females: 16.3 km2, males: 36.1 km2) compared to harbour seals from marine regions. Within the estuary, the animals utilised the fairway, river branches and tributaries. During the pupping season in June and July, four seals showed strongly reduced trip lengths and durations, increased daily haul out durations as well as smaller home ranges. Even though a continuous exchange with harbour seals from the Wadden Sea likely occurs, most individuals in this study spent the entire deployment duration inside the estuary. This indicates that the Elbe estuary provides a suitable habitat for harbour seals, despite extensive anthropogenic usage, calling for further studies on the consequences of living in such an industrialised habitat.
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Affiliation(s)
- Abbo van Neer
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstraße 6, 25761, Büsum, Germany
| | - Dominik Nachtsheim
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstraße 6, 25761, Büsum, Germany.
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation, Werftstraße 6, 25761, Büsum, Germany
| | - Thomas Taupp
- Department of Animal Ecology, Federal Institute of Hydrology (BfG), Am Mainzer Tor 1, 56068, Koblenz, Germany
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3
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Seki F, Takeda M. Novel and classical morbilliviruses: Current knowledge of three divergent morbillivirus groups. Microbiol Immunol 2022; 66:552-563. [PMID: 36151905 DOI: 10.1111/1348-0421.13030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/30/2022] [Accepted: 09/23/2022] [Indexed: 12/24/2022]
Abstract
Currently, seven species of morbillivirus have been classified. Six of these species (Measles morbillivirus, Rinderpest morbillivirus, Small ruminant morbillivirus, Canine morbillivirus, Phocine morbillivirus, and Cetacean morbillivirus) are highly infectious and cause serious systemic diseases in humans, livestock, domestic dogs, and wild animals. These species commonly use the host proteins signaling lymphocytic activation molecule (SLAM) and nectin-4 as receptors, and this usage contributes to their virulence. The seventh species (Feline morbillivirus: FeMV) is phylogenetically divergent from the six SLAM-using species. FeMV differs from the SLAM-using morbillivirus group in pathogenicity and infectivity, and is speculated to use non-SLAM receptors. Recently, novel species of morbilliviruses have been discovered in bats, rodents, and domestic pigs. Because the ability to use SLAM and nectin-4 is closely related to the infectivity and pathogenicity of morbilliviruses, investigation of the potential usage of these receptors is useful for estimating infectivity and pathogenicity. The SLAM-binding sites in the receptor-binding protein show high similarity among the SLAM-using morbilliviruses. This feature may help to estimate whether novel morbillivirus species can use SLAM as a receptor. A novel morbillivirus species isolated from wild mice diverged from the classified morbilliviruses in the phylogenetic tree, forming a third group separate from the SLAM-using morbillivirus group and FeMV. This suggests that the novel rodent morbillivirus may exhibit a different risk from the SLAM-using morbillivirus group, and analyses of its viral pathogenicity and infectivity toward humans are warranted.
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Affiliation(s)
- Fumio Seki
- Department of Virology 3, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan
| | - Makoto Takeda
- Department of Virology 3, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan
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4
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Liu X, Schjøtt SR, Granquist SM, Rosing-Asvid A, Dietz R, Teilmann J, Galatius A, Cammen K, O Corry-Crowe G, Harding K, Härkönen T, Hall A, Carroll EL, Kobayashi Y, Hammill M, Stenson G, Frie AK, Lydersen C, Kovacs KM, Andersen LW, Hoffman JI, Goodman SJ, Vieira FG, Heller R, Moltke I, Tange Olsen M. Origin and expansion of the world's most widespread pinniped: range-wide population genomics of the harbour seal (Phoca vitulina). Mol Ecol 2022; 31:1682-1699. [PMID: 35068013 PMCID: PMC9306526 DOI: 10.1111/mec.16365] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/07/2022] [Accepted: 01/11/2022] [Indexed: 11/26/2022]
Abstract
The harbour seal (Phoca vitulina) is the most widely distributed pinniped, occupying a wide variety of habitats and climatic zones across the Northern Hemisphere. Intriguingly, the harbour seal is also one of the most philopatric seals, raising questions as to how it colonised virtually the whole of the Northern Hemisphere. To shed light on the origin, remarkable range expansion, population structure and genetic diversity of this species, we used genotyping-by-sequencing to analyse ~13,500 biallelic SNPs from 286 individuals sampled from 22 localities across the species' range. Our results point to a Northeast Pacific origin, colonisation of the North Atlantic via the Canadian Arctic, and subsequent stepping-stone range expansions across the North Atlantic from North America to Europe, accompanied by a successive loss of genetic diversity. Our analyses further revealed a deep divergence between modern North Pacific and North Atlantic harbour seals, with finer-scale genetic structure at regional and local scales consistent with strong philopatry. The study provides new insights into the harbour seal's remarkable ability to colonise and adapt to a wide range of habitats. Furthermore, it has implications for current harbour seal subspecies delineations and highlights the need for international and national red lists and management plans to ensure the protection of genetically and demographically isolated populations.
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Affiliation(s)
- Xiaodong Liu
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Denmark
| | | | - Sandra M Granquist
- Icelandic Seal Centre, Höfðabraut 6, 530, Hvammstangi, Iceland.,Marine and Freshwater Research Institute, Institute of Freshwater Fisheries Fornubúðir 5, 220, Hafnarfjörður, Iceland
| | | | - Rune Dietz
- Marine Mammal Research, Department of Ecoscience, Aarhus University, Frederiksborgvej 399, 4000, Roskilde, Denmark
| | - Jonas Teilmann
- Marine Mammal Research, Department of Ecoscience, Aarhus University, Frederiksborgvej 399, 4000, Roskilde, Denmark
| | - Anders Galatius
- Marine Mammal Research, Department of Ecoscience, Aarhus University, Frederiksborgvej 399, 4000, Roskilde, Denmark
| | | | - Greg O Corry-Crowe
- Wildlife Evolution and Behavior Program, Florida Atlantic University, USA
| | - Karin Harding
- Department of Biological and Environmental Sciences, University of Gothenburg, Sweden
| | | | - Ailsa Hall
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, UK, KY16 8LB
| | - Emma L Carroll
- School of Biological Sciences, University of Auckland, Auckland, 1010, New Zealand
| | - Yumi Kobayashi
- Laboratory of Animal Ecology, Research Faculty of Agriculture, Hokkaido University, Japan
| | - Mike Hammill
- Maurice Lamontagne Institute, Fisheries and Oceans Canada, P.O. Box 1000, Mont-Joli, QC, Canada
| | - Garry Stenson
- Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, P.O. Box 5667, St. John's NL, Canada
| | | | | | - Kit M Kovacs
- Norwegian Polar Institute, Fram Centre, 9296, Tromsø, Norway
| | | | - Joseph I Hoffman
- Department of Animal Behaviour, University of Bielefeld, 33501, Bielefeld, Germany.,British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 OET, UK
| | - Simon J Goodman
- School of Biology, Faculty of Biological Sciences, University of Leeds, UK
| | - Filipe G Vieira
- Center for Genomic Medicine, Copenhagen University Hospitalet, Denmark
| | - Rasmus Heller
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Denmark
| | - Ida Moltke
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, Denmark
| | - Morten Tange Olsen
- Section for Evolutionary Genomics, Globe Institute, University of Copenhagen, Denmark
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5
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Hoekendijk JPA, Kellenberger B, Aarts G, Brasseur S, Poiesz SSH, Tuia D. Counting using deep learning regression gives value to ecological surveys. Sci Rep 2021; 11:23209. [PMID: 34853327 PMCID: PMC8636638 DOI: 10.1038/s41598-021-02387-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 11/10/2021] [Indexed: 12/03/2022] Open
Abstract
Many ecological studies rely on count data and involve manual counting of objects of interest, which is time-consuming and especially disadvantageous when time in the field or lab is limited. However, an increasing number of works uses digital imagery, which opens opportunities to automatise counting tasks. In this study, we use machine learning to automate counting objects of interest without the need to label individual objects. By leveraging already existing image-level annotations, this approach can also give value to historical data that were collected and annotated over longer time series (typical for many ecological studies), without the aim of deep learning applications. We demonstrate deep learning regression on two fundamentally different counting tasks: (i) daily growth rings from microscopic images of fish otolith (i.e., hearing stone) and (ii) hauled out seals from highly variable aerial imagery. In the otolith images, our deep learning-based regressor yields an RMSE of 3.40 day-rings and an [Formula: see text] of 0.92. Initial performance in the seal images is lower (RMSE of 23.46 seals and [Formula: see text] of 0.72), which can be attributed to a lack of images with a high number of seals in the initial training set, compared to the test set. We then show how to improve performance substantially (RMSE of 19.03 seals and [Formula: see text] of 0.77) by carefully selecting and relabelling just 100 additional training images based on initial model prediction discrepancy. The regression-based approach used here returns accurate counts ([Formula: see text] of 0.92 and 0.77 for the rings and seals, respectively), directly usable in ecological research.
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Affiliation(s)
- Jeroen P A Hoekendijk
- NIOZ Royal Netherlands Institute for Sea Research, 1790AB, Den Burg, The Netherlands.
- Wageningen University and Research, 6708PB, Wageningen, The Netherlands.
| | | | - Geert Aarts
- NIOZ Royal Netherlands Institute for Sea Research, 1790AB, Den Burg, The Netherlands
- Wageningen Marine Research, Wageningen University and Research, 1781AG, Den Helder, The Netherlands
- Wageningen University and Research, Wildlife Ecology and Conservation Group, 6708 PB, Wageningen, The Netherlands
| | - Sophie Brasseur
- Wageningen Marine Research, Wageningen University and Research, 1781AG, Den Helder, The Netherlands
| | - Suzanne S H Poiesz
- NIOZ Royal Netherlands Institute for Sea Research, 1790AB, Den Burg, The Netherlands
- Groningen Institute of Evolutionary Life Sciences, University of Groningen, 9700 CC, Groningen, The Netherlands
| | - Devis Tuia
- Ecole Polytechnique Fédérale de Lausanne (EPFL), 1950, Sion, Switzerland
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6
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Bethune E, Schulz-Kornas E, Lehnert K, Siebert U, Kaiser TM. Tooth Microwear Texture in the Eastern Atlantic Harbour Seals (Phoca vitulina vitulina) of the German Wadden Sea and Its Implications for Long Term Dietary and Ecosystem Changes. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.644019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Marine mammals are increasingly threatened in their habitat by various anthropogenic impacts. This is particularly evident in prey abundance. Understanding the dietary strategies of marine mammal populations can help predict implications for their future health status and is essential for their conservation. In this study we provide a striking example of a new dietary proxy in pinnipeds to document marine mammal diets using a dental record. In this novel approach, we used a combination of 49 parameters to establish a dental microwear texture (DMTA) as a dietary proxy of feeding behaviour in harbour seals. This method is an established approach to assess diets in terrestrial mammals, but has not yet been applied to pinnipeds. Our aim was to establish a protocol, opening DMTA to pinnipeds by investigating inter- and intra-individual variations. We analysed the 244 upper teeth of 78 Atlantic harbour seals (Phoca vitulina vitulina). The specimens were collected in 1988 along the North Sea coast (Wadden Sea, Germany) and are curated by the Zoological Institute of Kiel University, Germany. An increasing surface texture roughness from frontal to distal teeth was found and related to different prey processing biomechanics. Ten and five year old individuals were similar in their texture roughness, whereas males and females were similar to each other with the exception of their frontal dentition. Fall and summer specimens also featured no difference in texture roughness. We established the second to fourth postcanine teeth as reference tooth positions, as those were unaffected by age, sex, season, or intra-individual variation. In summary, applying indirect dietary proxies, such as DMTA, will allow reconstructing dietary traits of pinnipeds using existing skeletal collection material. Combining DMTA with time series analyses is a very promising approach to track health status in pinniped populations over the last decades. This approach opens new research avenues and could help detect dietary shifts in marine environments in the past and the future.
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7
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Abstract
Central place foragers are expected to offset travel costs between a central place and foraging areas by targeting productive feeding zones. Harbour seals (Phoca vitulina) make multi-day foraging trips away from coastal haul-out sites presumably to target rich food resources, but periodic track points from telemetry tags may be insufficient to infer reliably where, and how often, foraging takes place. To study foraging behaviour during offshore trips, and assess what factors limit trip duration, we equipped harbour seals in the German Wadden Sea with high-resolution multi-sensor bio-logging tags, recording 12 offshore trips from 8 seals. Using acceleration transients as a proxy for prey capture attempts, we found that foraging rates during travel to and from offshore sites were comparable to offshore rates. Offshore foraging trips may, therefore, reflect avoidance of intra-specific competition rather than presence of offshore foraging hotspots. Time spent resting increased by approx. 37 min/day during trips suggesting that a resting deficit rather than patch depletion may influence trip length. Foraging rates were only weakly correlated with surface movement patterns highlighting the value of integrating multi-sensor data from on-animal bio-logging tags (GPS, depth, accelerometers and magnetometers) to infer behaviour and habitat use.
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8
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Surprisingly long body length of the lungworm Parafilaroides gymnurus from common seals of the Dutch North Sea. Parasitol Res 2020; 119:1803-1817. [PMID: 32372130 DOI: 10.1007/s00436-020-06675-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 03/24/2020] [Indexed: 10/24/2022]
Abstract
Lungworms of the genera Parafilaroides and Otostrongylus are responsible for parasitic bronchopneumonia, the foremost disease of eastern Atlantic common seals (EACS, Phoca vitulina vitulina) in the Dutch North Sea. Recently, there have been increased reports of lungworm cases and observations of unusually long Parafilaroides sp. adults in this location. The initial aim of this study was to confirm the identity of the Parafilaroides species infecting this population. Parafilaroides are usually small and delicate, making them difficult to extract from host tissue, and there is often difficulty accessing fresh specimens for morphological study. The large size of the Dutch worms and the accessibility of specimens from numerous animals enabled the description and measurement of many intact specimens (N = 64) from multiple host animals (N = 20). Species identity was confirmed by targeted sequencing of ribosomal and mitochondrial DNA amplicons from a subset of worms. Worm morphology was consistent with descriptions for P. gymnurus, but the mature females were 1.9-fold and 3.4-fold longer than those recovered from French EACS (P ≤ 0.001) and Canadian western Atlantic common seals (Phoca vitulina concolor; P ≤ 0.0001). They were also significantly longer than mature female P. gymnurus described from other seal species, with the exception of those from harp seals of Les Escoumins, Quebec. We suggest that intraspecific genetic differences in P. gymnurus and the environment within the host could contribute to the variation reported here. This study is the first to describe P. gymnurus using morphological and molecular methods and should serve as a reference for identification of the species.
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Gilbert MJ, IJsseldijk LL, Rubio-García A, Gröne A, Duim B, Rossen J, Zomer AL, Wagenaar JA. After the bite: bacterial transmission from grey seals ( Halichoerus grypus) to harbour porpoises ( Phocoena phocoena). ROYAL SOCIETY OPEN SCIENCE 2020; 7:192079. [PMID: 32537205 PMCID: PMC7277243 DOI: 10.1098/rsos.192079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 03/24/2020] [Indexed: 06/11/2023]
Abstract
Recent population growth of the harbour porpoise (Phocoena phocoena), grey seal (Halichoerus grypus) and common seal (Phoca vitulina) in the North Sea has increased potential interaction between these species. Grey seals are known to attack harbour porpoises. Some harbour porpoises survive initially, but succumb eventually, often showing severely infected skin lesions. Bacteria transferred from the grey seal oral cavity may be involved in these infections and eventual death of the animal. In humans, seal bites are known to cause severe infections. In this study, a 16S rRNA-based microbiome sequencing approach is used to identify the oral bacterial diversity in harbour porpoises, grey seals and common seals; detect the potential transfer of bacteria from grey seals to harbour porpoises by biting and provide insights in the bacteria with zoonotic potential present in the seal oral cavity. β-diversity analysis showed that 12.9% (4/31) of the harbour porpoise skin lesion microbiomes resembled seal oral microbiomes, while most of the other skin lesion microbiomes also showed seal-associated bacterial species, including potential pathogens. In conclusion, this study shows that bacterial transmission from grey seals to harbour porpoises by biting is highly likely and that seal oral cavities harbour many bacterial pathogens with zoonotic potential.
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Affiliation(s)
- Maarten J. Gilbert
- Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands
- Reptile, Amphibian and Fish Conservation Netherlands (RAVON), Nijmegen, The Netherlands
| | - Lonneke L. IJsseldijk
- Faculty of Veterinary Medicine, Department of Biomolecular Health Sciences, Division of Pathology, Utrecht University, Utrecht, The Netherlands
| | - Ana Rubio-García
- Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands
- Sealcentre, Pieterburen, The Netherlands
- Department of Medical Microbiology and Infection Prevention, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Andrea Gröne
- Faculty of Veterinary Medicine, Department of Biomolecular Health Sciences, Division of Pathology, Utrecht University, Utrecht, The Netherlands
| | - Birgitta Duim
- Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands
- WHO Collaborating Centre for Campylobacter/OIE Reference Laboratory for Campylobacteriosis, Utrecht, The Netherlands
| | - John Rossen
- Department of Medical Microbiology and Infection Prevention, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Aldert L. Zomer
- Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands
- WHO Collaborating Centre for Campylobacter/OIE Reference Laboratory for Campylobacteriosis, Utrecht, The Netherlands
| | - Jaap A. Wagenaar
- Faculty of Veterinary Medicine, Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, The Netherlands
- WHO Collaborating Centre for Campylobacter/OIE Reference Laboratory for Campylobacteriosis, Utrecht, The Netherlands
- Wageningen Bioveterinary Research, Lelystad, The Netherlands
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Aarts G, Brasseur S, Poos JJ, Schop J, Kirkwood R, Kooten T, Mul E, Reijnders P, Rijnsdorp AD, Tulp I. Top‐down pressure on a coastal ecosystem by harbor seals. Ecosphere 2019. [DOI: 10.1002/ecs2.2538] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Geert Aarts
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
- NIOZ Royal Netherlands Institute for Sea Research Department of Coastal Systems Utrecht University P.O. Box 59, 1790 AB, Den Burg Texel The Netherlands
| | - Sophie Brasseur
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
| | - Jan Jaap Poos
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
- Aquaculture and Fisheries Group Wageningen University & Research Zodiac Building 122, De Elst 1 6708 WD Wageningen The Netherlands
| | - Jessica Schop
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
| | - Roger Kirkwood
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
| | - Tobias Kooten
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
- Institute for Biodiversity and Ecosystem Dynamics University of Amsterdam P.O. Box 94240 1090 GE Amsterdam The Netherlands
| | - Evert Mul
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
| | - Peter Reijnders
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
- Department of Aquatic Ecology & Water Quality Management (AEW) Wageningen University & Research Droevendaalsesteeg 3a, Building 100 6708 PB Wageningen The Netherlands
| | - Adriaan D. Rijnsdorp
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
- Aquaculture and Fisheries Group Wageningen University & Research Zodiac Building 122, De Elst 1 6708 WD Wageningen The Netherlands
| | - Ingrid Tulp
- Wageningen Marine Research Wageningen University & Research Ankerpark 27 1781 AG Den Helder The Netherlands
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11
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Jouta J, de Goeij P, Lok T, Velilla E, Camphuysen CJ, Leopold M, van der Veer HW, Olff H, Overdijk O, Piersma T. Unexpected dietary preferences of Eurasian Spoonbills in the Dutch Wadden Sea: spoonbills mainly feed on small fish not shrimp. JOURNAL OF ORNITHOLOGY 2018; 159:839-849. [PMID: 30997317 PMCID: PMC6435024 DOI: 10.1007/s10336-018-1551-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 02/26/2018] [Accepted: 03/07/2018] [Indexed: 06/09/2023]
Abstract
After an historical absence, over the last decades Eurasian Spoonbills Platalea leucorodia leucorodia have returned to breed on the barrier islands of the Wadden Sea. The area offers an abundance of predator-free nesting habitat, low degrees of disturbance, and an extensive intertidal feeding area with increasing stocks of brown shrimp Crangon crangon, the assumed main prey of P. leucorodia leucorodia. Nevertheless, newly established and expanding colonies of spoonbills have surprisingly quickly reached plateau levels. Here we tested the often stated assertion that spoonbills mainly rely on brown shrimp as food, by quantifying the diet of chicks on the basis of regurgitates and by analysis of blood isotopes using stable isotope Bayesian mixing models. Both methods showed that, rather than brown shrimp being the staple food of spoonbill chicks, small flatfish (especially plaice Pleuronectes platessa) and gobies (Pomatoschistus spp.) were their main prey. Unlike shrimp, small flatfish have been reported to be rather scarce in the Wadden Sea in recent years, which may explain the rapid saturation of colony size due to food-related density-dependent recruitment declines of growing colonies. By way of their diet and colony growth characteristics, spoonbills may thus indicate the availability of small fish in the Wadden Sea. We predict that the recovery to former densities of young flatfish and other juvenile/small fish in the Wadden Sea will be tracked by changing diets (more fish) and an increase in the size of Eurasian Spoonbill colonies across the Wadden Sea.
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Affiliation(s)
- Jeltje Jouta
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel The Netherlands
| | - Petra de Goeij
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel The Netherlands
- Werkgroep Lepelaar, Visserspad 10, 9142 VN Moddergat, The Netherlands
| | - Tamar Lok
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel The Netherlands
- Biostatistics and Population Biology, Centre d’Ecologie Fonctionnelle et Evolutive, UMR 5175, Montpellier, France
| | - Estefania Velilla
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel The Netherlands
- Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands
| | - Cornelis J. Camphuysen
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel The Netherlands
| | - Mardik Leopold
- Present Address: Ecosystems, Wageningen IMARES, P.O. Box 57, 1780 AB Den Helder, The Netherlands
| | - Henk W. van der Veer
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel The Netherlands
| | - Han Olff
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands
| | - Otto Overdijk
- Werkgroep Lepelaar, Visserspad 10, 9142 VN Moddergat, The Netherlands
| | - Theunis Piersma
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel The Netherlands
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