scholarly journals Peer Review #2 of "Stable isotope analysis (δ13C and δ15N) of soil nematodes from four feeding groups (v0.1)"

2016 ◽  
Author(s):  
T Moens
Keyword(s):  
Stable Isotope ◽  
Peer Review ◽  
Stable Isotope Analysis ◽  
Isotope Analysis ◽  
Soil Nematodes ◽  
Δ13c And Δ15n ◽  
Feeding Groups

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.

Trophic relationships of the platypus: insights from stable isotope and cheek pouch dietary analyses

2016 ◽  
Vol 67 (8) ◽  
pp. 1196 ◽  
Author(s):  
Melissa Klamt ◽  
Jenny A. Davis ◽  
Ross M. Thompson ◽  
Richard Marchant ◽  
Tom R. Grant
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Isotope Analysis ◽  
Trophic Relationships ◽  
Cheek Pouch ◽  
Insect Larvae ◽  
Top Down ◽  
Δ13c And Δ15n ◽  
Eastern Australia ◽  
Wide Range

The unique Australian monotreme, the platypus (Ornithorhynchus anatinus) potentially exerts a strong top-down influence on riverine food webs in eastern Australia. However, despite considerable interest in the evolutionary history and physiology of the platypus, little is known of its trophic relationships. To address this lack of knowledge we used stable isotope analysis, in combination with the analysis of food items stored in cheek pouches, to determine its position in a typical riverine food web. This was the essential first step in the process of designing a larger study to investigate the relative importance of top-down and bottom-up effects in rivers where the platypus occurs. We found that platypuses were feeding on a wide range of benthic invertebrates, particularly insect larvae. The similarity of δ13C and δ15N values recorded for the platypus, a native fish (Galaxias sp.) and the exotic mosquitofish (Gambusia holbrooki) indicated dietary overlap and potential competition for the same resources. Although cheek pouch studies identify most of the major groups of prey organisms, the potential for contribution of the soft-bodied organisms such as larval dipterans, is suggested by stable isotope analysis, indicating that the use of both techniques will be important in future ecological investigations.

scholarly journals Preservation in 70% ethanol solution does not affect δ13C and δ15N values of reindeer blood samples – relevance for stable isotope studies of diet

Rangifer ◽  
2008 ◽  
Vol 28 (1) ◽  
pp. 9 ◽  
Author(s):  
Duncan J. Halley ◽  
Masao Minagawa ◽  
Mauri Nieminen ◽  
Eldar Gaare
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Efficient Method ◽  
Isotope Analysis ◽  
Ethanol Solution ◽  
Δ13c And Δ15n ◽  
Blood Samples ◽  
Isotope Studies ◽  
Whole Blood Samples ◽  
Chloroform Methanol

We compared duplicate samples of whole blood samples from 18 reindeer that were preserved either by immediate freezing or by immersion in 70 % ethanol. All samples were dried at 60 °C, powdered, treated with 1:1 chloroform: methanol, and dried again before isotope analysis. There were no differences in the values of δ13C and δ15N between the methods of preservation. Isotopic differences were absolutely small (δ13C = 0.1±0.10/00; δ15N=0.2±0.20/00), random in direction, and within the limits of analytical precision for the mass spectrometer. Preservation in ethanol thus appears to be an effective and efficient method for preserving blood samples for stable isotope analysis under field conditions. Abstract in Norwegian / Sammendrag:Konservering av blodprøver fra rein i 70% etanolløsning påvirker ikke verdiene av δ13C and δ15N–verdiene og er en fullgod metode for analyse av stabile isotoperVi sammenlignet to og to prøver av blodprøver fra 18 reinsdyr. Prøvene var enten konservert ved umiddelbar frysing eller ved bruk av 70% etanol. Alle prøver ble tørket ved 60 °C, pulverisert og behandlet med kloroform:metanol i forholdet 1:1. Til slutt ble de tørket på nytt før gjennomføring av isotopanalysen. Vi fant ingen forskjell i verdiene av δ13C and δ15N mellom de to konserveringsmetodene. I absolutte verdier var isotopforskjellene små (δ13C = 0.1±0.1 0/00; δ15N=0.2±0.2 0/00). Forskjellene var tilfeldige og innenfor grensene for massespektrometerets presisjon. Bruk av etanol framstår som en effektiv og fullgod metode til konservering av blodprøver for analyse av stabile isotoper under feltforhold.

Stable isotope analysis reveals that humpback whales (Megaptera novaeangliae) primarily consume capelin (Mallotus villosus) in coastal Newfoundland, Canada

2021 ◽  
Author(s):  
Kelsey Johnson ◽  
Gail Davoren
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Isotope Analysis ◽  
Niche Overlap ◽  
Prey Type ◽  
Megaptera Novaeangliae ◽  
Humpback Whales ◽  
Mallotus Villosus ◽  
Δ13c And Δ15n ◽  
Capelin Mallotus Villosus

On the Newfoundland, Canada foraging ground, humpback whales (Megaptera novaeangliae (Borowski, 1781)) are found associated with a dominant forage fish species, capelin (Mallotus villosus (Müller, 1776), that experienced a population collapse in the early 1990s and has not recovered. Our primary goal was to reconstruct dietary proportions of humpback whales on their summer foraging grounds off the northeastern Newfoundland coast during July-August, 2016 and 2017 using a Bayesian stable isotope mixing model (MixSiar). Modelled dietary proportions were similar in both years, with capelin comprising ~90% of the diet. However, both δ13C and δ15N in humpback whale skin differed significantly between years, resulting in minimal dietary niche overlap (9%). Lipid-extracted and nonlipid-extracted skin samples were used to develop a lipid normalization equation: ∆13C = – 3.184 + 1.011(C:N). Overall, findings suggest that capelin is the primary prey type of humpback whales in coastal Newfoundland, despite the continued collapsed state of the capelin population. Findings also reiterate that dietary reconstruction from stable isotope analysis of cetacean skin can be misinterpreted without concurrently sampled isotopic ratios of potential prey types.

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