Spatial variation in a top marine predator’s diet at two regionally distinct sites

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dc.contributor.authorGosch, Martha
dc.contributor.authorCronin, Michelle A.
dc.contributor.authorRogan, Emer
dc.contributor.authorHunt, William
dc.contributor.authorLuck, Cian
dc.contributor.authorJessopp, Mark J.
dc.contributor.funderIrish Research Councilen
dc.contributor.funderDepartment of Agriculture, Food and the Marineen
dc.contributor.funderHigher Education Authorityen
dc.contributor.funderNational Parks and Wildlife Serviceen
dc.contributor.funderEnvironment and Climate Changeen
dc.contributor.funderMarine Instituteen
dc.date.accessioned2019-05-16T15:39:57Z
dc.date.available2019-05-16T15:39:57Z
dc.date.issued2019-01-02
dc.description.abstractIn ecological studies it is often assumed that predator foraging strategies and resource use are geographically and seasonally homogeneous, resulting in relatively static trophic relationships. However, certain centrally placed foragers (e.g. seals) often have terrestrial sites for breeding, resting, and moulting that are geographically distinct, and associated with different habitat types. Therefore, accurate estimations of predator diet at relevant spatial and temporal scales are key to understanding energetic requirements, predator-prey interactions and ecosystem structure. We investigate geographic variation in the diet of grey seals (Halichoerus grypus), a relatively abundant and widely distributed central place forager, to provide insights into geographic variation in resource use. Prey composition was identified using scat samples collected over concurrent timescales and a multivariate approach was used to analyse diet from two contrasting habitats. Regional differences in prey assemblages occurred within all years (2011–2013) and all seasons (ANOSIM, all p<0.05), apart from in winter. Telemetry data were used to identify core foraging areas and habitats most likely associated with scat samples collected at the two haul-out sites. Regional differences in the diet appear to reflect regional differences in the physical habitat features, with seals foraging in deeper waters over sandy substrates showing a higher prevalence of pelagic and bentho-pelagic prey species such as blue whiting and sandeels. Conversely, seals foraging in comparatively shallow waters had a greater contribution of demersal and groundfish species such as cephalopods and flatfish in their diet. We suggest that shallower waters enable seals to spend more time foraging along the benthos while remaining within aerobic dive limits, resulting in more benthic species in the diet. In contrast, the diet of seals hauled-out in areas adjacent to deeper waters indicates that either seals engage in a more pelagic foraging strategy, or that seals can spend less time at the benthos, resulting in comparatively more pelagic prey recovered in the diet. The substantial differences in prey assemblages over a small spatial scale (<300 km) demonstrates the importance of using regionally-specific diet information in ecosystem-based models to better account for different trophic interactions.en
dc.description.sponsorshipIrish Research Council (RS/2012/357); Department of Agriculture, Food and the Marine (FishKOSM (15/S/744)); Higher Education Authority (PRTLI4 programme Environment and Climate Change); Beaufort Marine Research Award (Sea Change Strategy and Strategy for Science Technology and Innovation 2006-2013); Marine Institute (Marine Research Sub-Programme of the National Development Plan 2007-2013)en
dc.description.statusPeer revieweden
dc.description.versionPublished Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.articleide0209032en
dc.identifier.citationGosch, M., Cronin, M., Rogan, E., Hunt, W., Luck, C. and Jessopp, M., 2019. Spatial variation in a top marine predator’s diet at two regionally distinct sites. PloS one, 14(1), (e0209032). DOI: 10.1371/journal.pone.0209032en
dc.identifier.doi10.1371/journal.pone.0209032en
dc.identifier.eissn1932-6203
dc.identifier.endpage20en
dc.identifier.issued1en
dc.identifier.journaltitlePLoS ONEen
dc.identifier.startpage1en
dc.identifier.urihttps://hdl.handle.net/10468/7928
dc.identifier.volume14en
dc.language.isoenen
dc.publisherPLoS ONEen
dc.relation.projectFishKOSM (15/S/744)en
dc.relation.urihttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.0209032
dc.rights© 2019 Gosch et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en
dc.subjectMarine predator dieten
dc.subjectEcological studiesen
dc.subjectGeographic variationen
dc.titleSpatial variation in a top marine predator’s diet at two regionally distinct sitesen
dc.typeArticle (peer-reviewed)en
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