Isotope turnover rates and diet-tissue discrimination in skin of<i>ex situ</i>Bottlenose Dolphins (<i>Tursiops truncatus</i>)

Browning, Nicole; Dold, Christopher; I-Fan, Jack; Worthy, Graham A. J.

doi:10.1242/jeb.093963

Cited by 85 publications

(99 citation statements)

References 62 publications

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“…All samples were frozen until analysis. All tissues sampled have similar tissue turnover rates (or half-life), estimated to be 2-3 weeks for shearwaters (cellular component; Barquete et al, 2013), gull chicks (whole blood; Bearhop et al, 2002;Ogden et al, 2004), and whales (skin; Todd, 1997;Browning et al, 2014).…”

Section: Study Site and Field Methodsmentioning

confidence: 99%

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

et al. 2017

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Understanding species interactions among top marine predators and interactions with their prey can provide important insight into community-level responses to changing prey availability and the role of apex predators as indicators of ecosystem change. On the northeast Newfoundland coast, marine predators rely on capelin (Mallotus villosus), a dominant forage fish, as a food source. Capelin migrate into coastal regions to spawn during July, essentially transforming the food supply from low during early summer (i.e., pre-spawning) to high later in the summer (i.e., spawning). During July-August, 2016, we used stable isotopic ratios of nitrogen (δ 15 N) and carbon (δ 13 C) to investigate shifts in dietary niche metrics at the predator group-level (trophic position, dietary niche breadth) and community-level (niche overlap, trophic diversity) for multiple marine predators under varying capelin availability. Predator groups included non-breeding shearwaters (great shearwater Ardenna gravis, sooty shearwater A. grisea), humpback whales (Megaptera novaeangliae), and gull chicks (herring gull Larus argentatus, great black-backed gull Larus marinus). We also tested the sensitivity of community-level dietary metrics to a variety of published trophic discrimination factors. Tissue samples from shearwaters (blood cellular component), gull chicks (whole blood), and whales (skin), representing average diets over 2-3 weeks, were collected during three periods (early, mid, late) corresponding to increasing capelin availability. Isotopic niche breadth (Standard Ellipse Area, SEA b ) narrowed and trophic position shifted toward higher δ 15 N for all predator groups as capelin availability increased, suggesting a higher reliance on capelin. Trophic diversity (distance to centroid) decreased with increased capelin availability, while pairwise niche overlap between predator groups was highly variable and sensitive to trophic discrimination factors. Findings suggest that although capelin is the dominant forage fish during the summer, predators rely on capelin as prey to varying degrees. Combining species-and community-level metrics of dietary niche and trophic diversity may provide a more complete picture of predator responses to prey availability and, thus, may be important monitoring tools to indicate changes in the food supply of marine predators.

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Section: Study Site and Field Methodsmentioning

confidence: 99%

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

et al. 2017

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“…These issues are discussed by Rosel et al (2017) for genetic assignment, and Hohn et al (2017) for SIR. One concern, in particular, is that SIR data tell us where animals have been foraging over the past few weeks to months (Browning et al 2014, Giménez et al 2016, not necessarily from where they originated (Hohn et al 2017). For example, in 10 cases, animals that were assigned via genetics to the BSE population with high probability had stable isotope signatures more indicative of a coastal stock animal (see Table S1 in the Supplement).…”

Section: Discussionmentioning

confidence: 99%

Where were they from? Modelling the source stock of dolphins stranded after the Deepwater Horizon oil spill using genetic and stable isotope data

Thomas¹,

Booth²,

Rosel³

et al. 2017

Endang. Species. Res.

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Understanding the source stock of common bottlenose dolphins Tursiops truncatus that stranded in the northern Gulf of Mexico subsequent to the Deepwater Horizon oil spill was essential to accurately quantify injury and apportion individuals to the appropriate stock. The aim of this study, part of the Natural Resource Damage Assessment (NRDA), was to estimate the proportion of the 932 recorded strandings between May 2010 and June 2014 that came from coastal versus bay, sound and estuary (BSE) stocks. Four sources of relevant information were available on overlapping subsets totaling 336 (39%) of the strandings: genetic stock assignment, stable isotope ratios, photo-ID and individual genetic-ID. We developed a hierarchical Bayesian model for combining these sources that weighted each data source for each stranding according to a measure of estimated precision: the effective sample size (ESS). The photo-and genetic-ID data were limited and considered to potentially introduce biases, so these data sources were excluded from analyses used in the NRDA. Estimates were calculated separately in 3 regions: East (of the Mississippi outflow), West (of the Mississippi outflow through Vermilion Bay, Louisiana) and Western Louisiana (west of Vermilion Bay to the Texas−Louisiana border); the estimated proportions of coastal strandings were, respectively 0.215 (95% CI: 0.169−0.263), 0.016 (0.036−0.099) and 0.622 (0.487−0.803). This method represents a general approach for integrating multiple sources of information that have differing uncertainties.

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“…δ (Caut et al 2009). These trophic discrimination factors (∆ values) are tissue-and species-specific, and are typically measured in controlled feeding studies (e.g., Hobson et al 1996, Browning et al 2014). …”

Section: Inferring Preymentioning

confidence: 99%

“…Three studies (Caut et al 2011, Browning et al 2014, Giménez et al 2016) have estimated trophic discrimination factors in cetaceans experimentally. We used values reported in Browning et al (Table 3), which we assumed would make up the largest proportion of protein assimilated by killer whales.…”

Section: Inferring Preymentioning

confidence: 99%

Variation in the diet of killer whales Orcinus orca at Marion Island, Southern Ocean

Reisinger¹,

Gröcke²,

Lübcker³

et al. 2016

Mar. Ecol. Prog. Ser.

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Citation for published item:eisingerD FF nd qr¤ okeD hFF nd v¤ ukerD iFvF nd wglymontD iFvF nd roelzelD eFF nd xio de fruynD FtF @PHITA 9rition in the diet of killer whles yrinus or t wrion sslndD outhern yenF9D wrine eology progress seriesFD SRW F ppF PTQEPURF Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

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Isotope turnover rates and diet-tissue discrimination in skin ofex situBottlenose Dolphins (Tursiops truncatus)

Cited by 85 publications

References 62 publications

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

Dietary Niche Shifts of Multiple Marine Predators under Varying Prey Availability on the Northeast Newfoundland Coast

Where were they from? Modelling the source stock of dolphins stranded after the Deepwater Horizon oil spill using genetic and stable isotope data

Variation in the diet of killer whales Orcinus orca at Marion Island, Southern Ocean

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