scholarly journals Stable Isotope Analyses of Multiple Tissues of Great Shearwaters (Ardenna Gravis) Reveals Long-Term Dietary Stability, Short-Term Changes in Diet, and Can be Used as a Tool to Monitor Food Webs

Diversity ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 163 ◽  
Author(s):  
Hong ◽  
Wiley ◽  
Powers ◽  
Michener ◽  
Kaufman ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Food Webs ◽  
Trophic Level ◽  
Isotope Analysis ◽  
Diet Shift ◽  
Turnover Rates ◽  
Δ13c And Δ15n ◽  
Isotopic Signatures ◽  
Over Time

The great shearwater (Ardenna gravis) is a common pelagic bird with a distribution that spans almost the entire Atlantic basin, which in conjunction with its relatively high abundance, makes great shearwaters an effective bio indicator. We compared δ13C and δ15N values from the feathers, red blood cells (RBCs), and plasma of great shearwaters collected in 2014 and 2015 from the waters off Massachusetts and Cape Cod. The δ13C and δ15N values of RBCs were quite constant between sampling periods and years, suggesting a generally stable food web over that time period. However, the δ13C of plasma indicates a small seasonal change in diet between July and September for both years, with plasma δ15N values suggesting a slight increase in trophic level late in summer. Comparison of the δ15N of RBCs and plasma indicates that great shearwaters experienced a diet shift during the first few weeks of summer 2014, but not in 2015. Comparisons with other studies suggest that these shearwaters feed at a lower trophic level than great shearwaters sampled in the Bay of Fundy and that there is a decrease in δ13C with increasing latitude, which could indicate a more pelagic diet in northern waters. Stable isotope analysis of the sixth primary feathers provided evidence that these feathers are molted in the Northern Hemisphere and that the diet of great shearwaters shortly after arrival was different in 2014 and 2015. This study demonstrates that within species comparisons of tissue isotopic signatures over time and comparisons of isotopic signatures of tissues with different turnover rates, can detect changes in diet and be used as a tool to monitor for changes in marine food webs over time and space. The relevant signals remain informative even in the absence of species-specific data on tissue-diet discrimination factors, tissue turnover rates, or knowledge of dietary components and their stable isotopic signatures, suggesting dietary changes indicative of a corresponding change in the food web.

Stable isotope analysis reveals partitioning in prey use by Kajikia audax (Istiophoridae), Thunnus albacares, Katsuwonus pelamis, and Auxis spp. (Scombridae) in the Eastern Tropical Pacific of Ecuador

2021 ◽  
Vol 19 (4) ◽  
Author(s):  
Rigoberto Rosas-Luis ◽  
Nancy Cabanillas-Terán ◽  
Carmen A. Villegas-Sánchez
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Stable Isotope Analysis ◽  
Trophic Ecology ◽  
Isotope Analysis ◽  
Middle Level ◽  
Food Sources ◽  
Thunnus Albacares ◽  
Katsuwonus Pelamis ◽  
Δ13c And Δ15n

Abstract Kajikia audax, Thunnus albacares, Katsuwonus pelamis, and Auxis spp. occupy high and middle-level trophic positions in the food web. They represent important sources for fisheries in Ecuador. Despite their ecological and economic importance, studies on pelagic species in Ecuador are scarce. This study uses stable isotope analysis to assess the trophic ecology of these species, and to determine the contribution of prey to the predator tissue. Isotope data was used to test the hypothesis that medium-sized pelagic fish species have higher δ15N values than those of the prey they consumed, and that there is no overlap between their δ13C and δ15N values. Results showed higher δ15N values for K. audax, followed by T. albacares, Auxis spp. and K. pelamis, which indicates that the highest position in this food web is occupied by K. audax. The stable isotope Bayesian ellipses demonstrated that on a long time-scale, these species do not compete for food sources. Moreover, δ15N values were different between species and they decreased with a decrease in predator size.

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.

Trophic guilds of generalist feeders in soil animal communities as indicated by stable isotope analysis (15N/14N)

2010 ◽  
Vol 100 (5) ◽  
pp. 511-520 ◽  
Author(s):  
K. Oelbermann ◽  
S. Scheu
Keyword(s):  
Stable Isotope ◽  
Food Webs ◽  
Trophic Level ◽  
A Priori ◽  
Isotope Analysis ◽  
Trophic Levels ◽  
Soil Arthropods ◽  
Trophic Guilds ◽  
Natural Variations ◽  
Animal Communities

AbstractWe investigated if the commonly used aggregation of organisms into trophic guilds, such as detritivores and predators, in fact represent distinct trophic levels. Soil arthropods of a forest-meadow transect were ascribed a priori to trophic guilds (herbivores, detritivores, predators and necrovores), which are often used as an equivalent to trophic levels. We analysed natural variations in 15N/14N ratios of the animals in order to investigate the trophic similarity of organisms within (a priori defined) trophic guilds. Using trophic guilds as an equivalent to trophic level, the assumed stepwise enrichment of 15N by 3.4‰ per trophic level did not apply to detritivores; they were only enriched in 15N by on average 1.5‰ compared to litter materials. Predators on average were enriched in 15N by 3.5‰ compared to detritivores. Within detritvores and predators δ15N signatures varied markedly, indicating that these trophic guilds are dominated by generalist feeders which form a gradient of organisms feeding on different resources. The results indicate that commonly used trophic guilds, in particular detritivores and predators, do not represent trophic levels but consist of subguilds, i.e. subsets of organisms differing in resource utilization. In particular, in soil and litter food webs where trophic level omnivory is common, the use of distinct trophic levels may be inappropriate. Guilds of species delineated by natural variations of stable isotope ratios are assumed to more adequately represent the structure of litter and soil food webs allowing a more detailed understanding of their functioning.

Identification of local populations of Lake Biwa catfish Silurus biwaensis in Japan on the basis of δ13C and δ15N analyses

1999 ◽  
Vol 77 (2) ◽  
pp. 258-266 ◽  
Author(s):  
Noriyuki Takai ◽  
Wataru Sakamoto
Keyword(s):  
Stable Isotope ◽  
Lake Biwa ◽  
Local Population ◽  
Isotope Analysis ◽  
Lepomis Macrochirus ◽  
Δ13c And Δ15n ◽  
Eastern Area ◽  
Isotopic Signatures ◽  
Local Populations ◽  
Ultrasonic Tracking

Carbon and nitrogen stable isotope ratios were used to examine the mixing of adult Lake Biwa catfish, Silurus biwaensis, in different areas of the lake and to identify the local populations. The isotopic signatures of its prey, the bluegill, Lepomis macrochirus, were also examined as indicators of each local food web. We analyzed 141 Lake Biwa catfish and 60 bluegills captured in the lake. The differences in δ13C values indicated that the two groups of catfish captured in the northern- and the southern-most spawning areas did not mix with each other frequently and were thus identified as local populations. The catfish captured in the mid-eastern area, where no spawning ground was found, were considered to be a group of migrators from the southernmost area, not a local population. These results are consistent with those obtained using ultrasonic tracking. It was therefore clearly demonstrated that stable isotope analysis is useful for identifying local populations of aquatic animals.

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 Young, Old, and Weathered Carbon—Part 2: Using Radiocarbon and Stable Isotopes to Identify Terrestrial Carbon Support of the Food Web in an Alkaline, Humic Lake

Radiocarbon ◽  
2015 ◽  
Vol 57 (3) ◽  
pp. 425-438 ◽  
Author(s):  
Evelyn M Keaveney ◽  
Paula J Reimer ◽  
Robert H Foy
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Food Webs ◽  
Isotope Analysis ◽  
Carbon Sources ◽  
Carbon Support ◽  
Trophic Levels ◽  
Terrestrial Carbon ◽  
Organic C ◽  
Fish Samples

Carbon (C) and nitrogen (N) stable isotope analysis (SIA) has been used to identify the terrestrial subsidy of freshwater food webs. However, SIA fails to differentiate between the contributions of old and recently fixed terrestrial C and consequently cannot fully determine the source, age, and biochemical quality of terrestrial carbon. Natural abundance radiocarbon (Δ14C) was used to examine the age and origin of carbon in Lower Lough Erne, Northern Ireland. 14C and stable isotope values were obtained from invertebrate, algae, and fish samples, and the results indicate that terrestrial organic C is evident at all trophic levels. High winter δ15N values in calanoid zooplankton (δ15N = 24‰) relative to phytoplankton and particulate organic matter (δ15N = 6‰ and 12‰, respectively) may reflect several microbial trophic levels between terrestrial C and calanoid invertebrates. Winter and summer calanoid Δ14C values show a seasonal switch between autochthonous and terrestrial carbon sources. Fish Δ14C values indicate terrestrial support at the highest trophic levels in littoral and pelagic food webs. 14C therefore is useful in attributing the source of carbon in freshwater in addition to tracing the pathway of terrestrial carbon through the food web.

A stable isotope study of a neotropical stream food web prior to the extirpation of its large amphibian community

2007 ◽  
Vol 23 (6) ◽  
pp. 643-651 ◽  
Author(s):  
Piet Verburg ◽  
Susan S. Kilham ◽  
Catherine M. Pringle ◽  
Karen R. Lips ◽  
Dana L. Drake
Keyword(s):  
Stable Isotope ◽  
Food Web ◽  
Isotope Analysis ◽  
Trophic Relationships ◽  
Population Declines ◽  
Isotopic Signatures ◽  
Top Predators ◽  
Forest Stream ◽  
Nitrogen Concentrations ◽  
Stable Isotope Study

Rapid and massive amphibian population declines have been reported throughout upland areas of the Neotropics. The abundance and species richness of Neotropical amphibian communities suggest that losses of this magnitude are likely to have strong effects at the ecosystem level. To improve understanding of the implications of their loss we used stable isotope analysis to examine trophic relationships in an ecosystem in which amphibians are dominant in a second-order forest stream at 750 m asl in Parque Nacional Omar Torrijos Herrera, Panama. We analysed δ13C, δ15N and C:N ratios of major biotic components (basal resources, invertebrates, amphibians, fish and reptiles) in the stream and of the adjacent riparian food web. Tadpoles (mean δ15N = 4.49‰) and adult amphibians (mean δ15N = 5.45‰) were intermediate links in the aquatic and terrestrial food web respectively. High δ15N signatures identified fish as top predators in the aquatic food web and snakes and the toad Bufo as top predators in the terrestrial food web. Isotopic signatures clearly distinguished between trophic groups of tadpoles: microbial feeders (Centrolenidae, δ15N range = 0.91–3.05‰), herbivores (Rana and Hyla, δ15N range = 4.74–5.15‰) and neuston feeders (Colostethus, δ15N range = 5.31–6.40‰). Dependence on autotrophic production was indicated by enriched signatures of carbon isotopes in pool dwellers versus those that reside in faster-flowing sections of the stream. High nitrogen concentrations in detrital matter (average 0.8%, C:N = 10.3) suggested that grazing tadpoles enhanced nitrogen fluxes and improved the quality of organic matter available to detritivores.

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.

Sign in / Sign up

Export Citation Format

Share Document