Effects of ethanol storage and lipid and urea extraction on δ<scp>15N</scp> and δ<scp>13C</scp> isotope ratios in a benthic elasmobranch, the bluespotted maskray Neotrygon kuhlii

Burgess, Katherine B.; Bennett, Michael B.

doi:10.1111/jfb.13164

Cited by 18 publications

(19 citation statements)

References 37 publications

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“…Our results support the recommendation that urea be extracted from batoid muscle tissue prior to stable isotope analysis due to increases in δ 15 N and C:N ratios following UE (Burgess and Bennett ; Carlisle et al ). In contrast, δ 13 C and C:N ratios did not change following LE, suggesting muscle lipid content was low.…”

Section: Discussionsupporting

confidence: 89%

“…UE is recommended for elasmobranch tissues (Kim and Koch ; Li et al ; Burgess and Bennett ; Carlisle et al ) due to urea retention in body tissues for osmoregulation (Hazon et al ), and because urea is relatively depleted in 14 N (Gannes et al ). In the present study, UE led to a ~ 1‰ increase in δ 15 N values of stingray muscle tissue (+0.9 ± 0.2‰ for P. ater ; +1.1 ± 0.3‰ for H. australis ).…”

Section: Discussionmentioning

confidence: 99%

“…Thus, high urea concentrations in elasmobranch tissues lower δ 15 N values, and this can result in an underestimation of trophic positions (Kim and Koch ; Carlisle et al ). Experimental studies examining the influence of urea on elasmobranch δ 15 N have illustrated that urea‐extracted tissues generally have higher δ 15 N and C:N ratios relative to untreated tissues although results are not consistent across all species (Kim and Koch ; Li et al ; Burgess and Bennett ; Carlisle et al ). The increase in C:N ratio following urea‐extraction has important implications for assessing tissue lipid content based on the C:N ratios.…”

mentioning

confidence: 99%

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Effects of lipid and urea extraction on stable isotope values (δ¹³C and δ¹⁵N) of two batoids: A call for more species‐specific investigations

Crook

Barnett

Sheaves

et al. 2019

Limnology & Ocean Methods

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The presence of lipids and urea in elasmobranch tissues can affect carbon (δ13C) and nitrogen (δ15N) stable isotope values, introducing bias in food web interpretations. Information on how lipids and urea affect δ13C/δ15N is only available for < 5% of ~ 1150 described elasmobranch species and results are highly variable among existing studies. Here, we investigate the effects of lipid and urea extraction on δ13C, δ15N, and C:N ratios in muscle and blood plasma of two batoids (Pastinachus ater and Himantura australis) and examine the influence of lipid/urea extraction on isotopic niche size and overlap. Lipid extraction (LE) did not affect δ13C, δ15N, or C:N ratios, suggesting low lipid content. Urea extraction (UE), however, increased δ15N and C:N in muscle. The ~ 1‰ δ15N increase represents a shift of ~ 0.5 trophic levels relative to bulk samples, highlighting the importance of UE to accurately assess trophic positions. Although there was no effect of any treatment on niche size, the probability of P. ater occurring within the niche of H. australis increased following UE. Overall, results suggest that urea should be removed from muscle prior to analysis, but LE is not required. Given the interspecific variability in the effects of lipid/urea on elasmobranch δ13C/δ15N, more studies are needed to assess the effects of lipid and urea on a broader range of species to produce a generalized understanding. Where no species‐specific data are available, we recommend pilot samples are analyzed to determine if LE is needed prior to preparation of the overall sample set.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of lipid and urea extraction on stable isotope values (δ¹³C and δ¹⁵N) of two batoids: A call for more species‐specific investigations

Crook

Barnett

Sheaves

et al. 2019

Limnology & Ocean Methods

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“…Muscle samples were soaked in deionized water for 24–48 h to remove urea [11]. Manta ray muscle tissue and zooplankton samples were dried at 50–60°C for 24–48 h and then each was homogenized.…”

Section: Methodsmentioning

confidence: 99%

Manta birostris, predator of the deep? Insight into the diet of the giant manta ray through stable isotope analysis

et al. 2016

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The characterization of diet for the giant manta ray Manta birostris has been problematic given their large-scale movement patterns and the difficulty in obtaining stomach contents from this species. The large majority of existing information is based on observational data limited to feeding events at the sea surface during daylight. Recently discovered aggregation sites for the giant manta ray off mainland Ecuador are some of the most accessible to date and provide a unique opportunity for researchers to gather much needed information on this elusive species. To assess how important surface zooplankton is to giant manta ray diet, we conducted stable isotope analysis (15N and 13C) on M. birostris muscle and surface zooplankton. Trophic position estimates placed M. birostris overall at a secondary consumer level of approximately 3.4 but there was large variation in δ15N and δ13C values among individuals. Manta birostris muscle tissue δ13C values were also not consistent with this species feeding predominantly on surface zooplankton and suggest that the majority of dietary intake is of mesopelagic origin. Given the conservative life history and fisheries pressure on large planktivores, knowledge of their trophic role and foraging strategies is essential to better understand their ecology and develop effective conservation measures.

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“…Muscle samples were rinsed in deionised water for c . 5 min to remove urea following Burgess and Bennett () and along with histotroph and yolk were freeze‐dried and homogenised. A c .…”

Section: Methodsmentioning

confidence: 99%

Mother–embryo isotope fractionation in the pygmy devilray Mobula kuhlii cf. eregoodootenkee

Broadhurst

Domit

Trevizani

et al. 2019

Journal of Fish Biology

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We determined stable‐isotope ratios for replicate muscle tissues in 13 gravid Mobula kuhlii cf. eregoodootenkee (110.4–120.4 cm disc width; WD) and their embryos (7.0–42.3 cm WD) and also yolks and histrotroph, to assess the potential implications for juvenile nutrition and habitat use. Irrespective of their development in the uterus, embryos had similar δ13C values in their muscle tissue as the mothers and both had greater values than in the histotroph. During gestation, δ13C values increased across all sample types. However, while embryo muscle tissue and the histotroph were associated with increasing 15N levels during embryonic development, this was depleted in the mothers’ muscle tissue and yolk. Although speculative, the observed variation in stable‐isotope ratios might imply a dietary shift among gravid females during their early gestation. Irrespective of the underlying mechanisms, the results indicate neonates will have relatively greater δ15N values than post‐partum females, which would probably confound juvenile foraging‐ecology estimates.

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Effects of ethanol storage and lipid and urea extraction on δ¹⁵N and δ¹³C isotope ratios in a benthic elasmobranch, the bluespotted maskray Neotrygon kuhlii

Cited by 18 publications

References 37 publications

Effects of lipid and urea extraction on stable isotope values (δ¹³C and δ¹⁵N) of two batoids: A call for more species‐specific investigations

Effects of lipid and urea extraction on stable isotope values (δ¹³C and δ¹⁵N) of two batoids: A call for more species‐specific investigations

Manta birostris, predator of the deep? Insight into the diet of the giant manta ray through stable isotope analysis

Mother–embryo isotope fractionation in the pygmy devilray Mobula kuhlii cf. eregoodootenkee

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Effects of ethanol storage and lipid and urea extraction on δ15N and δ13C isotope ratios in a benthic elasmobranch, the bluespotted maskray Neotrygon kuhlii

Cited by 18 publications

References 37 publications

Effects of lipid and urea extraction on stable isotope values (δ13C and δ15N) of two batoids: A call for more species‐specific investigations

Effects of lipid and urea extraction on stable isotope values (δ13C and δ15N) of two batoids: A call for more species‐specific investigations

Manta birostris, predator of the deep? Insight into the diet of the giant manta ray through stable isotope analysis

Mother–embryo isotope fractionation in the pygmy devilray Mobula kuhlii cf. eregoodootenkee

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Product

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Effects of ethanol storage and lipid and urea extraction on δ¹⁵N and δ¹³C isotope ratios in a benthic elasmobranch, the bluespotted maskray Neotrygon kuhlii

Effects of lipid and urea extraction on stable isotope values (δ¹³C and δ¹⁵N) of two batoids: A call for more species‐specific investigations

Effects of lipid and urea extraction on stable isotope values (δ¹³C and δ¹⁵N) of two batoids: A call for more species‐specific investigations