Isotopic niche differs between seal and fish‐eating killer whales (Orcinus orca) in northern Norway
Abstract Ecological diversity has been reported for killer whales (Orcinus orca) throughout the North Atlantic but patterns of prey specialization have remained poorly understood. We quantify interindividual dietary variations in killer whales (n = 38) sampled throughout the year in 2017–2018 in nor...
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ftdoajarticles:oai:doaj.org/article:8db653b190004c4189222a2fecb6fc93 2023-05-15T17:03:39+02:00 Isotopic niche differs between seal and fish‐eating killer whales (Orcinus orca) in northern Norway Eve Jourdain Clare Andvik Richard Karoliussen Anders Ruus Dag Vongraven Katrine Borgå 2020-05-01T00:00:00Z https://doi.org/10.1002/ece3.6182 https://doaj.org/article/8db653b190004c4189222a2fecb6fc93 EN eng Wiley https://doi.org/10.1002/ece3.6182 https://doaj.org/toc/2045-7758 2045-7758 doi:10.1002/ece3.6182 https://doaj.org/article/8db653b190004c4189222a2fecb6fc93 Ecology and Evolution, Vol 10, Iss 9, Pp 4115-4127 (2020) ecological niche ecological variation prey specialization stable isotopes trophic level Ecology QH540-549.5 article 2020 ftdoajarticles https://doi.org/10.1002/ece3.6182 2022-12-31T06:15:26Z Abstract Ecological diversity has been reported for killer whales (Orcinus orca) throughout the North Atlantic but patterns of prey specialization have remained poorly understood. We quantify interindividual dietary variations in killer whales (n = 38) sampled throughout the year in 2017–2018 in northern Norway using stable isotopic nitrogen (δ15N: 15N/14N) and carbon (δ13C: 13C/12C) ratios. A Gaussian mixture model assigned sampled individuals to three differentiated clusters, characterized by disparate nonoverlapping isotopic niches, that were consistent with predatory field observations: seal‐eaters, herring‐eaters, and lumpfish‐eaters. Seal‐eaters showed higher δ15N values (mean ± SD: 12.6 ± 0.3‰, range = 12.3–13.2‰, n = 10) compared to herring‐eaters (mean ± SD: 11.7 ± 0.2‰, range = 11.4–11.9‰, n = 19) and lumpfish‐eaters (mean ± SD: 11.6 ± 0.2‰, range = 11.3–11.9, n = 9). Elevated δ15N values for seal‐eaters, regardless of sampling season, confirmed feeding at high trophic levels throughout the year. However, a wide isotopic niche and low measured δ15N values in the seal‐eaters, compared to that of whales that would eat solely seals (δN‐measured = 12.6 vs. δN‐expected = 15.5), indicated a diverse diet that includes both fish and mammal prey. A narrow niche for killer whales sampled at herring and lumpfish seasonal grounds supported seasonal prey specialization reflective of local peaks in prey abundance for the two fish‐eating groups. Our results, thus, show differences in prey specialization within this killer whale population in Norway and that the episodic observations of killer whales feeding on prey other than fish are a consistent behavior, as reflected in different isotopic niches between seal and fish‐eating individuals. Article in Journal/Newspaper Killer Whale North Atlantic Northern Norway Orca Orcinus orca Killer whale Directory of Open Access Journals: DOAJ Articles Norway Ecology and Evolution 10 9 4115 4127 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
ecological niche ecological variation prey specialization stable isotopes trophic level Ecology QH540-549.5 |
spellingShingle |
ecological niche ecological variation prey specialization stable isotopes trophic level Ecology QH540-549.5 Eve Jourdain Clare Andvik Richard Karoliussen Anders Ruus Dag Vongraven Katrine Borgå Isotopic niche differs between seal and fish‐eating killer whales (Orcinus orca) in northern Norway |
topic_facet |
ecological niche ecological variation prey specialization stable isotopes trophic level Ecology QH540-549.5 |
description |
Abstract Ecological diversity has been reported for killer whales (Orcinus orca) throughout the North Atlantic but patterns of prey specialization have remained poorly understood. We quantify interindividual dietary variations in killer whales (n = 38) sampled throughout the year in 2017–2018 in northern Norway using stable isotopic nitrogen (δ15N: 15N/14N) and carbon (δ13C: 13C/12C) ratios. A Gaussian mixture model assigned sampled individuals to three differentiated clusters, characterized by disparate nonoverlapping isotopic niches, that were consistent with predatory field observations: seal‐eaters, herring‐eaters, and lumpfish‐eaters. Seal‐eaters showed higher δ15N values (mean ± SD: 12.6 ± 0.3‰, range = 12.3–13.2‰, n = 10) compared to herring‐eaters (mean ± SD: 11.7 ± 0.2‰, range = 11.4–11.9‰, n = 19) and lumpfish‐eaters (mean ± SD: 11.6 ± 0.2‰, range = 11.3–11.9, n = 9). Elevated δ15N values for seal‐eaters, regardless of sampling season, confirmed feeding at high trophic levels throughout the year. However, a wide isotopic niche and low measured δ15N values in the seal‐eaters, compared to that of whales that would eat solely seals (δN‐measured = 12.6 vs. δN‐expected = 15.5), indicated a diverse diet that includes both fish and mammal prey. A narrow niche for killer whales sampled at herring and lumpfish seasonal grounds supported seasonal prey specialization reflective of local peaks in prey abundance for the two fish‐eating groups. Our results, thus, show differences in prey specialization within this killer whale population in Norway and that the episodic observations of killer whales feeding on prey other than fish are a consistent behavior, as reflected in different isotopic niches between seal and fish‐eating individuals. |
format |
Article in Journal/Newspaper |
author |
Eve Jourdain Clare Andvik Richard Karoliussen Anders Ruus Dag Vongraven Katrine Borgå |
author_facet |
Eve Jourdain Clare Andvik Richard Karoliussen Anders Ruus Dag Vongraven Katrine Borgå |
author_sort |
Eve Jourdain |
title |
Isotopic niche differs between seal and fish‐eating killer whales (Orcinus orca) in northern Norway |
title_short |
Isotopic niche differs between seal and fish‐eating killer whales (Orcinus orca) in northern Norway |
title_full |
Isotopic niche differs between seal and fish‐eating killer whales (Orcinus orca) in northern Norway |
title_fullStr |
Isotopic niche differs between seal and fish‐eating killer whales (Orcinus orca) in northern Norway |
title_full_unstemmed |
Isotopic niche differs between seal and fish‐eating killer whales (Orcinus orca) in northern Norway |
title_sort |
isotopic niche differs between seal and fish‐eating killer whales (orcinus orca) in northern norway |
publisher |
Wiley |
publishDate |
2020 |
url |
https://doi.org/10.1002/ece3.6182 https://doaj.org/article/8db653b190004c4189222a2fecb6fc93 |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Killer Whale North Atlantic Northern Norway Orca Orcinus orca Killer whale |
genre_facet |
Killer Whale North Atlantic Northern Norway Orca Orcinus orca Killer whale |
op_source |
Ecology and Evolution, Vol 10, Iss 9, Pp 4115-4127 (2020) |
op_relation |
https://doi.org/10.1002/ece3.6182 https://doaj.org/toc/2045-7758 2045-7758 doi:10.1002/ece3.6182 https://doaj.org/article/8db653b190004c4189222a2fecb6fc93 |
op_doi |
https://doi.org/10.1002/ece3.6182 |
container_title |
Ecology and Evolution |
container_volume |
10 |
container_issue |
9 |
container_start_page |
4115 |
op_container_end_page |
4127 |
_version_ |
1766057553470423040 |