Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at the southern limit of their European range (Eastern English Channel)
Abstract Sympatric harbour (Phoca vitulina) and grey seals (Halichoerus grypus) are increasingly considered potential competitors, especially since recent local declines in harbour seal numbers while grey seal numbers remained stable or increased at their European core distributions. A better unders...
Published in: | Ecology and Evolution |
---|---|
Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2021
|
Subjects: | |
Online Access: | https://doi.org/10.1002/ece3.7739 https://doaj.org/article/41a28b9c66194646ae3f2d17b84207b0 |
id |
ftdoajarticles:oai:doaj.org/article:41a28b9c66194646ae3f2d17b84207b0 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:41a28b9c66194646ae3f2d17b84207b0 2023-05-15T16:33:37+02:00 Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at the southern limit of their European range (Eastern English Channel) Yann Planque Jérôme Spitz Matthieu Authier Gaël Guillou Cécile Vincent Florence Caurant 2021-08-01T00:00:00Z https://doi.org/10.1002/ece3.7739 https://doaj.org/article/41a28b9c66194646ae3f2d17b84207b0 EN eng Wiley https://doi.org/10.1002/ece3.7739 https://doaj.org/toc/2045-7758 2045-7758 doi:10.1002/ece3.7739 https://doaj.org/article/41a28b9c66194646ae3f2d17b84207b0 Ecology and Evolution, Vol 11, Iss 15, Pp 10004-10025 (2021) feeding strategies foraging ecology intraindividual variability marine top predators pinnipeds stable isotopes Ecology QH540-549.5 article 2021 ftdoajarticles https://doi.org/10.1002/ece3.7739 2022-12-31T07:07:35Z Abstract Sympatric harbour (Phoca vitulina) and grey seals (Halichoerus grypus) are increasingly considered potential competitors, especially since recent local declines in harbour seal numbers while grey seal numbers remained stable or increased at their European core distributions. A better understanding of the interactions between these species is critical for conservation efforts. This study aimed to identify the trophic niche overlap between harbour and grey seals at the southern limit of their European range, in the Baie de Somme (BDS, Eastern English Channel, France), where numbers of resident harbour seals and visiting grey seals are increasing exponentially. Dietary overlap was identified from scat contents using hierarchical clustering. Isotopic niche overlap was quantified using δ13C and δ15N isotopic values from whiskers of 18 individuals, by estimating isotopic standard ellipses with a novel hierarchical model developed in a Bayesian framework to consider both intraindividual variability and interindividual variability. Foraging areas of these individuals were identified from telemetry data. The three independent approaches provided converging results, revealing a high trophic niche overlap due to consumption of benthic flatfish. Two diet clusters were dominated by either small or large benthic flatfish; these comprised 85.5% [CI95%: 80.3%–90.2%] of harbour seal scats and 46.8% [35.1%–58.4%] of grey seal scats. The narrower isotopic niche of harbour seals was nested within that of grey seals (58.2% [22.7%–100%] overlap). Grey seals with isotopic values similar to harbour seals foraged in coastal waters close to the BDS alike harbour seals did, suggesting the niche overlap may be due to individual grey seal strategies. Our findings therefore provide the basis for potential competition between both species (foraging on benthic flatfish close to the BDS). We suggest that a continued increase in seal numbers and/or a decrease in flatfish supply in this area could cause/amplify competitive interactions ... Article in Journal/Newspaper harbour seal Phoca vitulina Directory of Open Access Journals: DOAJ Articles Ecology and Evolution 11 15 10004 10025 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
feeding strategies foraging ecology intraindividual variability marine top predators pinnipeds stable isotopes Ecology QH540-549.5 |
spellingShingle |
feeding strategies foraging ecology intraindividual variability marine top predators pinnipeds stable isotopes Ecology QH540-549.5 Yann Planque Jérôme Spitz Matthieu Authier Gaël Guillou Cécile Vincent Florence Caurant Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at the southern limit of their European range (Eastern English Channel) |
topic_facet |
feeding strategies foraging ecology intraindividual variability marine top predators pinnipeds stable isotopes Ecology QH540-549.5 |
description |
Abstract Sympatric harbour (Phoca vitulina) and grey seals (Halichoerus grypus) are increasingly considered potential competitors, especially since recent local declines in harbour seal numbers while grey seal numbers remained stable or increased at their European core distributions. A better understanding of the interactions between these species is critical for conservation efforts. This study aimed to identify the trophic niche overlap between harbour and grey seals at the southern limit of their European range, in the Baie de Somme (BDS, Eastern English Channel, France), where numbers of resident harbour seals and visiting grey seals are increasing exponentially. Dietary overlap was identified from scat contents using hierarchical clustering. Isotopic niche overlap was quantified using δ13C and δ15N isotopic values from whiskers of 18 individuals, by estimating isotopic standard ellipses with a novel hierarchical model developed in a Bayesian framework to consider both intraindividual variability and interindividual variability. Foraging areas of these individuals were identified from telemetry data. The three independent approaches provided converging results, revealing a high trophic niche overlap due to consumption of benthic flatfish. Two diet clusters were dominated by either small or large benthic flatfish; these comprised 85.5% [CI95%: 80.3%–90.2%] of harbour seal scats and 46.8% [35.1%–58.4%] of grey seal scats. The narrower isotopic niche of harbour seals was nested within that of grey seals (58.2% [22.7%–100%] overlap). Grey seals with isotopic values similar to harbour seals foraged in coastal waters close to the BDS alike harbour seals did, suggesting the niche overlap may be due to individual grey seal strategies. Our findings therefore provide the basis for potential competition between both species (foraging on benthic flatfish close to the BDS). We suggest that a continued increase in seal numbers and/or a decrease in flatfish supply in this area could cause/amplify competitive interactions ... |
format |
Article in Journal/Newspaper |
author |
Yann Planque Jérôme Spitz Matthieu Authier Gaël Guillou Cécile Vincent Florence Caurant |
author_facet |
Yann Planque Jérôme Spitz Matthieu Authier Gaël Guillou Cécile Vincent Florence Caurant |
author_sort |
Yann Planque |
title |
Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at the southern limit of their European range (Eastern English Channel) |
title_short |
Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at the southern limit of their European range (Eastern English Channel) |
title_full |
Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at the southern limit of their European range (Eastern English Channel) |
title_fullStr |
Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at the southern limit of their European range (Eastern English Channel) |
title_full_unstemmed |
Trophic niche overlap between sympatric harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) at the southern limit of their European range (Eastern English Channel) |
title_sort |
trophic niche overlap between sympatric harbour seals (phoca vitulina) and grey seals (halichoerus grypus) at the southern limit of their european range (eastern english channel) |
publisher |
Wiley |
publishDate |
2021 |
url |
https://doi.org/10.1002/ece3.7739 https://doaj.org/article/41a28b9c66194646ae3f2d17b84207b0 |
genre |
harbour seal Phoca vitulina |
genre_facet |
harbour seal Phoca vitulina |
op_source |
Ecology and Evolution, Vol 11, Iss 15, Pp 10004-10025 (2021) |
op_relation |
https://doi.org/10.1002/ece3.7739 https://doaj.org/toc/2045-7758 2045-7758 doi:10.1002/ece3.7739 https://doaj.org/article/41a28b9c66194646ae3f2d17b84207b0 |
op_doi |
https://doi.org/10.1002/ece3.7739 |
container_title |
Ecology and Evolution |
container_volume |
11 |
container_issue |
15 |
container_start_page |
10004 |
op_container_end_page |
10025 |
_version_ |
1766023297284177920 |