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Identifying foraging habitats of adult female long-nosed fur seal Arctocephalus forsteri based on vibrissa stable isotopes

Citation

Foo, D and Hindell, M and McMahon, C and Goldsworthy, S, Identifying foraging habitats of adult female long-nosed fur seal Arctocephalus forsteri based on vibrissa stable isotopes, Marine Ecology - Progress Series, 628 pp. 223-234. ISSN 0171-8630 (2019) [Refereed Article]


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Copyright 2019 Inter-Research

DOI: doi:10.3354/meps13113

Abstract

We investigated how foraging ecotypes of female long-nosed fur seals Arctocephalus forsteri could be identified from vibrissa stable isotopes. We collected regrowths of vibrissae from adult females (n = 18) from Cape Gantheaume, Kangaroo Island, South Australia, from 2 breeding seasons (2016, 2017). The period represented by the regrowth was known, and 8 individuals were administered with 15N-enriched glycine as a biomarker to mark the start date of the regrowth. Non-glycine-marked and glycine-marked vibrissae were used to estimate the rate of the individual vibrissa regrowth. Using individual growth rates (0.18 ± 0.04 mm d-1), we reconstructed a stable isotope (δ13C and δ15N) time series for each regrowth and allocated them to corresponding at-sea locations either based on geolocation tracks (n = 14) or foraging habitat type (shelf or oceanic) based on diving data (n = 2) of the sampled seals. Mean (±SD) δ15N from vibrissa segments was higher when females foraged on the continental shelf region (16.1 ± 0.7‰, n = 29) compared to oceanic waters (15.1 ± 0.7‰, n = 106) in 2017, whereas it was similar in both regions in 2016 (shelf: 15.3 ± 0.4‰, n = 13; oceanic: 15.4 ± 0.4‰, n = 15). Based on the stable isotope signatures of vibrissa segments, model-based clustering analysis correctly classified 79.8% as originating from shelf or oceanic foraging habitats. This demonstrates the potential of using vibrissa stable isotopes for studying the foraging ecology of an important top marine predator.

Item Details

Item Type:Refereed Article
Keywords:fur seal, isoscape, foraging strategies, trophic dynamics, continental shelf, oceanic, marine top predators
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological Oceanography
Objective Division:Environment
Objective Group:Ecosystem Assessment and Management
Objective Field:Ecosystem Assessment and Management of Marine Environments
UTAS Author:Foo, D ( Dahlia Foo)
UTAS Author:Hindell, M (Professor Mark Hindell)
ID Code:136828
Year Published:2019
Deposited By:Ecology and Biodiversity
Deposited On:2020-01-20
Last Modified:2020-05-25
Downloads:0

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