Carbon and nitrogen discrimination factors for elasmobranch soft tissues based on a long-term controlled feeding study

Kim, Sora L.; Casper, Dave; Galván‐Magaña, Felipe; Ochoa-Díaz, Ruth; Hernández-Aguilar, Sandra Berenice; Koch, Paul L.

doi:10.1007/s10641-011-9919-7

Cited by 113 publications

(142 citation statements)

References 77 publications

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“…2a) Kim et al (2012a) Mixing model results indicated clear dif ferences between oceanic whitetip diet estimated from plasma (short-term diet) and muscle (long-term diet) (Fig. 2b).…”

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confidence: 90%

“…N for white muscle tissue and blood plasma were adjusted for dif fe rent tissuespecific diet tissue discrimination factor (DTDF) values (Kim et al 2012a) based on captive leopard sharks Triakis semifasciata (see subsection 'Statistical and diet analyses'). We did not perform chemical or arithmetic lipid extractions/corrections since C:N ratios for all tissues were < 3.5 (Post et al 2007; see Table 2) and lipid extractions have been shown to have little effect on shark muscle tissue (Hussey et al 2010a).…”

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confidence: 99%

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confidence: 99%

“…In order to account for tissue-specific differences in DTDFs, we corrected both muscle and plasma for DTDFs determined in a controlled laboratory study (Kim et al 2012a). We chose DTDFs according to Kim et al (2012a) for 2 reasons. First, it is the only study to date that has assessed the DTDFs of both muscle and plasma in sharks, from both tissues in the same ani- N values (± SD) were calculated for both flying fish and various squids.…”

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confidence: 99%

“…Since it is not known which squid species are specifically consumed by whitetips, we assumed that pelagic predator (tunas, dolphinfish, and wahoo) stomach contents adequately sampled the squid prey species available, and we did not identify the squid samples to the species level. We used DTDFs from Kim et al (2012a) and mean prey SIA values (see Table 2) to generate median and 95% confidence interval estimates for the proportion of large pelagic teleosts, forage fish, and squids in the short-term diet of oceanic whitetips using blood plasma δ 13 C and δ 15 N values and in the long-term diet using white muscle δ 13 C and δ 15 N values using the Bayesian mixing model MixSIR. We ran 10 6 iterations and uninfor med priors when generating mixing model estimates.…”

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confidence: 99%

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Diet shift and site-fidelity of oceanic whitetip sharks Carcharhinus longimanus along the Great Bahama Bank

Madigan

Brooks²,

Bond³

et al. 2015

Mar. Ecol. Prog. Ser.

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Identifying the driving forces behind oceanic pelagic shark movements is key to a better understanding of their life history. Some oceanic pelagic shark species have been shown to aggregate in specific regions to mate and/or exploit abundant food resources. The oceanic whitetip shark Carcharhinus longimanus, a subtropical, ectothermic, oceanic pelagic shark that has experienced severe population declines, aggregates seasonally around Cat Island (CI) in The Bahamas. Large pelagic teleosts (e.g. billfish, tunas, and dolphinfish) are abundant in this region and oceanic whitetips are anecdotally reported to feed heavily on recreationally caught teleosts. However, it was unknown whether feeding habits at CI substantially differ from longer-term feeding habits. We used tag-recapture to assess site-fidelity of adult oceanic whitetips to CI and stable isotope analysis (SIA) of 2 different tissues (blood plasma and white muscle) to compare short-and long-term feeding patterns. The relatively high recapture rate (20.3%) confirmed that individual whitetips exhibit site-fidelity to CI. The aggregation consisted of adult individuals; females were more common, more than half were gravid, and no physical or behavioral evidence of mating or parturition was observed at CI. SIA-based Bayesian mixing model estimates of short-term (near CI) diets showed more large pelagic teleosts (72%) than in long-term diets (47%), showing a spatiotemporal difference in oceanic whitetip feeding habits. This suggests that availability of large teleost prey is a possible mechanism underpinning site-fidelity and aggregation of whitetips at CI. These results provide insight into the function of one of the last known aggregations of this once-abundant top predator.

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“…2a) Kim et al (2012a) Mixing model results indicated clear dif ferences between oceanic whitetip diet estimated from plasma (short-term diet) and muscle (long-term diet) (Fig. 2b).…”

mentioning

confidence: 90%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Diet shift and site-fidelity of oceanic whitetip sharks Carcharhinus longimanus along the Great Bahama Bank

Madigan

Brooks²,

Bond³

et al. 2015

Mar. Ecol. Prog. Ser.

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Enhancing insights into foraging specialization in the world's largest fish using a multi‐tissue, multi‐isotope approach

Wyatt

Matsumoto

Chikaraishi

et al. 2019

Ecological Monographs

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Intra‐species variability in foraging strategies may be common, which has significant implications for efforts to understand and manage enigmatic species like the whale shark Rhincodon typus. The ecological relevance of differences in tissue isotopes within and between individuals in the context of foraging however depends on understanding tissue turnover times and carbon (Δ13C) and nitrogen (Δ15N) discrimination, which can vary with physiology, metabolism, and diet quality. Here, we examine isotope dynamics in captive R. typus as a basis for enhanced ecological insights into wild populations of the world's largest fish and other enigmatic species. A variable diet, principally consisting of two krill (Euphausia pacifica and Euphausia superba) provided an average of 48 ± 20 MJ/d (mean ± SD), or 2.7 ± 1.3 times basal metabolic requirements. On this diet, in agreement with allometric relationships, large body sizes (3,000–4,000 kg) were matched by slow plasma and cartilage turnover rates (empirically derived as 9 months and 3 yr, respectively), which provide tissue‐specific limits on the timescales over which we can isotopically detect diet changes in this species. Average diet‐to‐tissue discrimination showed significant variation between tissues (plasma and cartilage), and among growing and fasting individuals (Δ13C range, 1.5 to 5.5‰; Δ15N range, −0.1 to 2.9‰). Assimilation rates increased with temperature and were higher for the smaller E. pacifica (15 ± 2 mm) than E. superba (48 ± 2 mm). Growth significantly lowered both Δ15Nplasma and Δ15Ncartilage, with inappetence markedly reducing Δ15Nplasma and Δ13Cplasma, as well as significantly altering blood biochemistry. Captive findings facilitated the first robust multi‐tissue growth‐ and nutrition‐corrected isotope analysis of a wild R. typus population, suggesting individual foraging specialization on low trophic level mid‐ocean or coastal prey. Long‐term fasting during ocean‐basin‐scale migrations may be common and such metabolic effects should be carefully quantified when isotopically assessing intra‐species foraging differences. The metabolically constrained multi‐tissue, multi‐isotope approach described can facilitate ecological insights that are indispensable for effective conservation and management of globally threatened, but poorly understood, species by identifying differences in key foraging areas and target prey within and between individuals.

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Trophic position estimates of marine teleosts using amino acid compound specific isotopic analysis

Bradley

Wallsgrove

Choy

et al. 2015

Limnology & Ocean Methods

130

230

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The increasing use of trophic position (TP) for assessing and describing ecosystems has resulted in the emergence of novel techniques for accurate and accessible measurements. The strength of amino acid compound specific nitrogen isotopic analysis (AA-CSIA) lies in its ability to determine TP using a single organism, utilizing the isotopic differences between two or more amino acids (AAs). However, calculating TP from this technique relies upon the predictability of isotopic differences across consumer types and consistency among ecosystems. The goal of this study was to use wild samples to evaluate 15 N enrichment between AA groups with differing trophic fractionation patterns, termed the trophic discrimination factor (TDF AA ), and determine an accurate value for calculating TPs of marine teleosts. Using a large sample size (224 samples of 47 species) across a broad range of TPs (2.0-4.5, estimated by stomach content analysis [SCA]) and marine ecosystems, we derived TDF AA values that explained up to 80% of the variability between TP calculations from SCA and AA-CSIA. We found a TDF AA value of 5.7 6 0.3& using the difference between d 15 N values of glutamic acid and phenylalanine, 2& lower than the most commonly used value of 7.6 6 1.3&. The weighted mean of several AAs resulted in the same value for TDF AA , but provided greater agreement with TPs from SCA. For more reliable TP calculations in marine teleosts, our results strongly advocate a lower TDF AA and the use of weighted mean AA d 15 N values from triplicate analyses.

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Carbon and nitrogen discrimination factors for elasmobranch soft tissues based on a long-term controlled feeding study

Cited by 113 publications

References 77 publications

Diet shift and site-fidelity of oceanic whitetip sharks Carcharhinus longimanus along the Great Bahama Bank

Diet shift and site-fidelity of oceanic whitetip sharks Carcharhinus longimanus along the Great Bahama Bank

Enhancing insights into foraging specialization in the world's largest fish using a multi‐tissue, multi‐isotope approach

Trophic position estimates of marine teleosts using amino acid compound specific isotopic analysis

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