scholarly journals Effects of preservation methods of muscle tissue from upper-trophic level reef fishes on stable isotope values (δ13C andδ15N)

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e874 ◽  
Author(s):  
Christopher D. Stallings ◽  
James A. Nelson ◽  
Katherine L. Rozar ◽  
Charles S. Adams ◽  
Kara R. Wall ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Muscle Tissue ◽  
Trophic Level ◽  
Reef Fishes ◽  
Preservation Methods

scholarly journals Effects of preservation methods of muscle tissue from upper-trophic level reef fishes on stable isotope values (δ13C and δ15N)

2014 ◽  
Author(s):  
Christopher D. Stallings ◽  
James A. Neslon ◽  
Katherine L. Rozar ◽  
Charles S. Adams ◽  
Kara R. Wall ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Mass Balance ◽  
Muscle Tissue ◽  
Stable Isotope Analysis ◽  
Trophic Level ◽  
Isotopic Ratio ◽  
Isotope Analysis ◽  
Reef Fishes ◽  
Δ13c And Δ15n ◽  
Preservation Methods

Research that uses stable isotope analysis often involves a delay between sample collection in the field and laboratory processing, therefore requiring preservation to prevent or reduce tissue degradation and associated isotopic compositions. Although there is a growing literature describing the effects of various preservation techniques, the results are often contextual, unpredictable and vary among taxa, suggesting the need to treat each species individually. We conducted a controlled experiment to test the effects of four preservation methods of muscle tissue from four species of upper trophic-level reef fish collected from the eastern Gulf of Mexico (Red Grouper Epinephelus morio, Gag Mycteroperca microlepis, Scamp Mycteroperca phenax, and Red Snapper Lutjanus campechanus). We used a paired design to measure the effects on isotopic values for carbon and nitrogen after storage using ice, 95% ethanol, and sodium chloride (table salt), against that in a liquid nitrogen control. Mean offsets for both δ13C and δ15N values from controls were lowest for samples preserved on ice, intermediate for those preserved with salt, and highest with ethanol. Within species, both salt and ethanol significantly enriched the δ15N values in nearly all comparisons. Ethanol also had strong effects on the δ13C values in all three groupers. Conversely, for samples preserved on ice, we did not detect a significant offset in either isotopic ratio for any of the focal species. Previous studies have addressed preservation-induced offsets in isotope values using a mass balance correction that accounts for changes in the isotope value to that in the C/N ratio. We tested the application of standard mass balance corrections for isotope values that were significantly affected by the preservation methods and found generally poor agreement between corrected and control values. The poor performance by the correction may have been due to preferential loss of lighter isotopes and corresponding low levels of mass loss with a substantial change in the isotope value of the sample. Regardless of mechanism, it was evident that accounting for offsets caused by different preservation methods was not possible using the standard correction. Caution is warranted when interpreting the results from specimens stored in either ethanol or salt, especially when using those from multiple preservation techniques. We suggest the use of ice as the preferred preservation technique for muscle tissue when conducting stable isotope analysis as it is widely available, inexpensive, easy to transport and did not impart a significant offset in measured isotopic values. Our results provide additional evidence that preservation effects on stable isotope analysis can be highly contextual, thus requiring their effects to be measured and understood for each species and isotopic ratio of interest before addressing research questions.

scholarly journals Effects of preservation methods of muscle tissue from upper-trophic level reef fishes on stable isotope values (δ13C and δ15N)

2014 ◽  
Author(s):  
Christopher D. Stallings ◽  
James A. Neslon ◽  
Katherine L. Rozar ◽  
Charles S. Adams ◽  
Kara R. Wall ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Mass Balance ◽  
Muscle Tissue ◽  
Stable Isotope Analysis ◽  
Trophic Level ◽  
Isotopic Ratio ◽  
Isotope Analysis ◽  
Reef Fishes ◽  
Δ13c And Δ15n ◽  
Preservation Methods

Research that uses stable isotope analysis often involves a delay between sample collection in the field and laboratory processing, therefore requiring preservation to prevent or reduce tissue degradation and associated isotopic compositions. Although there is a growing literature describing the effects of various preservation techniques, the results are often contextual, unpredictable and vary among taxa, suggesting the need to treat each species individually. We conducted a controlled experiment to test the effects of four preservation methods of muscle tissue from four species of upper trophic-level reef fish collected from the eastern Gulf of Mexico (Red Grouper Epinephelus morio, Gag Mycteroperca microlepis, Scamp Mycteroperca phenax, and Red Snapper Lutjanus campechanus). We used a paired design to measure the effects on isotopic values for carbon and nitrogen after storage using ice, 95% ethanol, and sodium chloride (table salt), against that in a liquid nitrogen control. Mean offsets for both δ13C and δ15N values from controls were lowest for samples preserved on ice, intermediate for those preserved with salt, and highest with ethanol. Within species, both salt and ethanol significantly enriched the δ15N values in nearly all comparisons. Ethanol also had strong effects on the δ13C values in all three groupers. Conversely, for samples preserved on ice, we did not detect a significant offset in either isotopic ratio for any of the focal species. Previous studies have addressed preservation-induced offsets in isotope values using a mass balance correction that accounts for changes in the isotope value to that in the C/N ratio. We tested the application of standard mass balance corrections for isotope values that were significantly affected by the preservation methods and found generally poor agreement between corrected and control values. The poor performance by the correction may have been due to preferential loss of lighter isotopes and corresponding low levels of mass loss with a substantial change in the isotope value of the sample. Regardless of mechanism, it was evident that accounting for offsets caused by different preservation methods was not possible using the standard correction. Caution is warranted when interpreting the results from specimens stored in either ethanol or salt, especially when using those from multiple preservation techniques. We suggest the use of ice as the preferred preservation technique for muscle tissue when conducting stable isotope analysis as it is widely available, inexpensive, easy to transport and did not impart a significant offset in measured isotopic values. Our results provide additional evidence that preservation effects on stable isotope analysis can be highly contextual, thus requiring their effects to be measured and understood for each species and isotopic ratio of interest before addressing research questions.

Matching and mismatching stable isotope (δ13C and δ15N) ratios in fin and muscle tissue among fish species: a critical review

2013 ◽  
Vol 160 (7) ◽  
pp. 1633-1644 ◽  
Author(s):  
Trevor J. Willis ◽  
Christopher J. Sweeting ◽  
Sarah J. Bury ◽  
Sean J. Handley ◽  
Julie C. S. Brown ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Muscle Tissue ◽  
Fish Species ◽  
Critical Review ◽  
Δ13c And Δ15n

scholarly journals Stable Isotope Food Web Analysis of a Large Subtropical Lake: Alternative Explanations for15N Enrichment of Pelagic vs. Littoral Fisheries

2003 ◽  
Vol 3 ◽  
pp. 613-622 ◽  
Author(s):  
Karl E. Havens ◽  
Binhe Gu ◽  
Brian Fry ◽  
Carol Kendall
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Food Webs ◽  
Trophic Level ◽  
Stable Isotope Ratio ◽  
Pelagic Zone ◽  
Primary Producers ◽  
Subtropical Lake ◽  
Primary Consumers ◽  
Habitat Enrichment

The food webs of littoral, pelagic, and littoral-pelagic ecotone (interface) regions of a large subtropical lake were investigated using stable isotope ratio methods, expanding the focus of a previous fish-only study to include other food web components such as primary producers and invertebrates. In these food webs, δ13C increased ~4o/oo and δ15N increased ~10o/oo from primary producers to fish. The δ15N of fish was ~9o/oo in the littoral zone, ~10 o/oo in the ecotone, and ~12o/oo in the pelagic zone. The cross-habitat enrichment in fish15N corresponded with both an increase in the size of fish and an increase in the δ15N of primary consumers (mollusks). Despite larger body size in the pelagic zone, fish in all three habitats appear to occur at the same average trophic level (TL = 4), assuming an enrichment factor of 3.4o/oo per trophic level, and normalizing to the δ15N of primary consumers.

How ‘Best’ to Determine Trophic Levels in Archaeological Agricultural Communities

2017 ◽  
Author(s):  
Linda Reynard
Keyword(s):  
Stable Isotope ◽  
Trophic Level ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Trophic Levels ◽  
Bone Collagen ◽  
Carbon And Nitrogen ◽  
Agricultural Communities ◽  
Plant Remains ◽  
Isotope System

Stable isotope ratios of bone collagen have been used to determine trophic levels in diverse archaeological populations. The longest established and arguably most successful isotope system has been nitrogen, followed by carbon, and more recently hydrogen. These trophic level proxies rely on a predictable change in isotope ratio with each trophic level step; however, this requirement may not always be met, which can lead to difficulties in interpreting archaeological evidence. In agricultural communities, in particular, there are several possible complications to the interpretation of nitrogen and carbon isotopes. Recent approaches to overcome these limitations include better quantification and understanding of the influences on consumer isotope ratios; inclusion of evidence from plant remains; further investigation of apatite δ13C—collagen δ13C spacing in bones; measurement of carbon and nitrogen isotope ratios in individual amino acids, rather than collagen; and development of other stable isotope proxies for trophic level, such as hydrogen isotopes.

Use of stable-carbon and -nitrogen isotopes to assess weaning and fasting in female polar bears and their cubs

2001 ◽  
Vol 79 (3) ◽  
pp. 499-511 ◽  
Author(s):  
S C Polischuk ◽  
K A Hobson ◽  
M A Ramsay
Keyword(s):  
Stable Isotope ◽  
Trophic Level ◽  
Nitrogen Isotopes ◽  
Milk Proteins ◽  
Milk Lipid ◽  
Polar Bears ◽  
Stable Carbon ◽  
Stable Isotope Analyses ◽  
The Impact ◽  
Isotope Analyses

In some species, stable-isotope techniques can provide insights into dietary regimens where there are temporal shifts in trophic level or feeding frequency. We determined stable carbon (δ13C) and nitrogen (δ15N) isotope values for plasma and milk proteins and δ13C values for milk lipids from female polar bears (Ursus maritimus) and cubs to (i) ascertain whether cubs are at a higher trophic level than their mothers as a result of nursing and whether we can determine when weaning occurs, and (ii) determine the impact of seasonal fasting on δ13C and δ15N values. The plasma δ13C values for mothers and cubs were similar to milk-protein δ13C values and were significantly enriched in 13C compared with those for milk lipid. Plasma from cubs of the year (COYs) in spring, when milk was their only diet, was isotopically enriched in 15N by 1.0‰ over that of their mothers (δ15N = 21.5 ± 0.8‰ (mean ± SD) for cubs and 20.5 ± 0.5‰ for mothers) and depleted in 13C by 0.8 ‰ (δ13C = –19.6 ± 0.5‰ for cubs and –18.8 ± 0.8‰ for mothers). For bears who fasted between summer and fall (3–4 months), plasma became depleted in 13C by 0.5‰ and in 15N by 1‰. Plasma from females, who had fasted from summer to spring (7–8 months) and given birth to cubs, became enriched in 13C by 0.7‰ and in 15N by 2‰. By using stable-isotope analyses we were able to show that (i) young cubs were at a higher trophic level than their mother when milk was their only food source, and (ii) seasonal fasting influenced δ13C and δ15N values. However, we were not able to use stable-isotope analyses to determine the exact time of weaning.

Sexual segregation in distribution, diet and trophic level of seabirds: insights from stable isotope analysis

2011 ◽  
Vol 158 (10) ◽  
pp. 2199-2208 ◽  
Author(s):  
Richard A. Phillips ◽  
Rona A. R. McGill ◽  
Deborah A. Dawson ◽  
Stuart Bearhop
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Trophic Level ◽  
Isotope Analysis ◽  
Sexual Segregation
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