Use of epidermal mucus in elasmobranch stable isotope studies: a pilot study using the giant manta ray (Manta birostris)

2018 ◽  
Vol 69 (2) ◽  
pp. 336 ◽  
Author(s):  
K. B. Burgess ◽  
M. Guerrero ◽  
A. J. Richardson ◽  
M. B. Bennett ◽  
A. D. Marshall
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Time Course ◽  
Feeding Habits ◽  
Isotope Analysis ◽  
Δ13c Values ◽  
Significant Difference ◽  
Manta Birostris ◽  
Epidermal Mucus ◽  
Manta Ray

Stable isotope analysis of tissues with different turnover rates allows for a broader temporal view of a species’ feeding habits. Epidermal mucus is a rapid to medium turnover ‘tissue’ in teleost fish, but its use in elasmobranch dietary studies is unknown. In the present study, we conducted stable isotope analysis on mucus and muscle from the giant manta ray Manta birostris. Mucus δ13C values were depleted and closer to surface zooplankton δ13C values compared with muscle, whereas there was no significant difference in δ15N values between these two tissue types. Using diet tissue discrimination factors from the literature, there was no significant difference in the expected prey profile between muscle and epidermal mucus. However, a broader range in δ13C values of expected prey was shown for mucus compared with muscle. The results suggest that if M. birostris mucus is indicative of recent dietary intake, resource use during aggregative behaviour off Ecuador is broader, but with no obvious resource switching. The present study is the first example of using bulk stable isotope analysis to evaluate mucus to investigate feeding ecology in elasmobranchs. However, the time course for the change in mucus isotope signature still needs to be determined through controlled feeding studies in an aquarium setting.

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

2016 ◽  
Vol 3 (11) ◽  
pp. 160717 ◽  
Author(s):  
Katherine B. Burgess ◽  
Lydie I. E. Couturier ◽  
Andrea D. Marshall ◽  
Anthony J. Richardson ◽  
Scarla J. Weeks ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Large Scale ◽  
Trophic Position ◽  
Isotope Analysis ◽  
Stomach Contents ◽  
Foraging Strategies ◽  
Manta Birostris ◽  
Elusive Species ◽  
Manta Ray

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 ( 15 N and 13 C) 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 δ 15 N and δ 13 C values among individuals. Manta birostris muscle tissue δ 13 C 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.

scholarly journals Trophic interactions of meso- and macrozooplankton and fish in the Iceland Sea as evaluated by fatty acid and stable isotope analysis

2012 ◽  
Vol 69 (7) ◽  
pp. 1277-1288 ◽  
Author(s):  
Hildur Petursdottir ◽  
Stig Falk-Petersen ◽  
Astthor Gislason
Keyword(s):  
Fatty Acid ◽  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Trophic Interactions ◽  
Trophic Ecology ◽  
Feeding Habits ◽  
Isotope Analysis ◽  
Trophic Levels ◽  
Amphipod Species ◽  
Blue Whiting

Abstract Petursdottir, H., Falk-Petersen, S., and Gislason, A. 2012. Trophic interactions of meso- and macrozooplankton and fish in the Iceland Sea as evaluated by fatty acid and stable isotope analysis. – ICES Journal of Marine Science, 69: . A trophic study was carried out in August of 2007 and 2008 on the pelagic ecosystem in the Subarctic Iceland Sea. Carbon and nitrogen stable isotopes and fatty acid biomarkers were used to study trophic linkages and the trophic ecology of the most important pelagic species in this ecosystem, with emphasis on capelin (Mallotus villosus). According to 15N enrichment results, there are 3–4 trophic levels in this ecosystem excluding organisms of the microbial loop and birds and mammals. The primarily herbivorous copepod Calanus hyperboreus occupies the lowest trophic level of the animal species studied, and adult capelin and blue whiting (Micromesistius poutassou) occupy the highest level. Calanus spp. proved to be an important dietary component of most of the species studied, the euphausiid species Thysanoessa inermis and T. longicaudata being exceptions. The chaetognath Eukrohnia hamata is a pure carnivore, feeding heavily on Calanus spp., whereas most of the other zooplankton species studied practice an omnivorous–carnivorous feeding mode. The amphipod species Themisto libellula is important in the diet of adult capelin. Adult capelin and blue whiting share the same feeding habits and could therefore be competing for food.

scholarly journals The influence of food quantity on carbon and nitrogen stable isotope values in southern African spiny mice (Acomys spinosissimus)

2015 ◽  
Vol 93 (5) ◽  
pp. 345-351 ◽  
Author(s):  
G.N. Robb ◽  
S. Woodborne ◽  
P.R. de Bruin ◽  
K. Medger ◽  
N.C. Bennett
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analysis ◽  
Lipid Extraction ◽  
C:N Ratio ◽  
Isotope Analysis ◽  
Single Species ◽  
Carbon And Nitrogen ◽  
Food Quantity ◽  
Significant Difference ◽  
Influence Of Food

Stable isotope analysis is frequently applied as a tool to examine dietary patterns in animals. However, some of the underlying assumptions associated with using this approach are increasingly being questioned. We carried out a controlled diet experiment on the southern African spiny mouse (Acomys spinosissimus Peters, 1852) to test a number of aspects relating to these assumptions and also examine the hypothesis that stable isotopes, especially δ15N, can be used to provide evidence of nutritional stress. We compared the δ13C and δ15N values of livers and blood from animals that were fed ad libitum with animals undergoing a 10% reduction in food supply. Food-restricted animals showed no significant difference in δ15N; however, δ13C values of both liver and blood were depleted. Restricted animals also had a significantly lower C:N ratio. We examined the role of lipids and found following lipid extraction that both livers and lipids still showed the same separation in carbon values. Tissue–diet discrimination values were also calculated and found to be higher for both Δ13C and Δ15N compared with other mice species. Empirical values for discrimination rates were then compared with values calculated using an alternative method based on employing generic values and were found to be dissimilar, suggesting the use of generic values are not always appropriate. Our results highlight the need for greater understanding of the assumptions associated with using stable isotope analysis to examine diet and we suggest that studying a single species under captive conditions presents an ideal method to begin to test these hypotheses.

Trophic niche differentiation mirrors intra-island population structure of Galápagos marine iguanas (Amblyrhynchus cristatus)

2019 ◽  
Author(s):  
Sten Anslan ◽  
Timm Reinhardt ◽  
Patrick Fink ◽  
Mario Brauns ◽  
Nicolás Peñafiel ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Genetic Differentiation ◽  
Stable Isotope Analysis ◽  
Isotope Analysis ◽  
Trophic Niche ◽  
Ecological Niches ◽  
Amblyrhynchus Cristatus ◽  
Significant Difference ◽  
Marine Iguanas ◽  
Marine Iguana

Abstract Background: Differences in the trophic niche often underlie ecological specialization of individuals and can promote ecological speciation of populations, but studies showing a link between differences in the trophic niche and genetic differentiation of populations are rare. On the island of San Cristóbal (Galapágos archipelago), a strong genetic differentiation between two relatively proximate populations (subspecies; Amblyrhynchus cristatus mertensi and A. c. godzilla) of marine iguanas along the coastline has been observed. Here, we explore whether this genetic differentiation is mirrored in the iguanas’ trophic niche. Results: Although, no significant difference in the number of consumed algal taxa between subspecies were detected, the Schoener index exhibited low diet overlap between A. c. mertensi and A. c. godzilla. The latter was also demonstrated by the PERMANOVA analysis with significantly different diet OTU composition from the fecal samples between subspecies. Stable isotope analysis revealed that subspecies identity was overall more important than site for the iguanas’ resource use. Conclusions: By applying a metabarcoding approach on feces samples in combination with stable isotope analysis of skin sheds, we found that A. c. mertensi and A. c. godzilla differ in their ecological niches. Moreover, stable isotope analysis indicated that marine iguana populations have low spatial foraging distances, which, together with the diet partitioning patterns, might explain, at least partially, the lack of gene flow between these geographically proximate marine iguana populations. Key words: diet analysis, trophic niche, metabarcoding, stable isotopes, marine iguanas, Amblyrhynchus cristatus

scholarly journals European lobsters utilise Atlantic salmon wastes in coastal integrated multi-trophic aquaculture systems

2020 ◽  
Vol 12 ◽  
pp. 485-494
Author(s):  
A Baltadakis ◽  
J Casserly ◽  
L Falconer ◽  
M Sprague ◽  
TC Telfer
Keyword(s):  
Stable Isotope ◽  
Atlantic Salmon ◽  
Stable Isotope Analysis ◽  
Isotope Analysis ◽  
Flow Analysis ◽  
Control Site ◽  
Fish Feed ◽  
Fatty Acid Profiling ◽  
Significant Difference ◽  
Fouling Organisms

In this study, we investigated if juvenile European lobsters Homarus gammarus would eat waste from Atlantic salmon Salmo salar cages in a coastal integrated multi-trophic aquaculture (IMTA) setup and if there were any impacts on growth. Trophic interactions between salmon and lobsters were assessed using δ15N and δ13C stable isotope analysis and fatty acid profiling from fish feed as indicators of nutrient flow. Analysis revealed that lobsters directly utilised particulate waste from salmon production, as levels of indicator fatty acids from salmon feed were significantly higher in lobster tissues near the fish cages compared to the control site. Route of uptake may have been direct consumption of waste feed or faecal material or indirectly through fouling organisms. Stable isotope analysis did not indicate nutrient transfer to lobsters, suggesting that the duration of the study and/or the amount of waste consumed was not sufficient for stable isotope analysis. Lobsters grew significantly over the trial period at both sites, but there was no significant difference in lobster growth between the sites. Our results show a trophic relationship between salmon and lobsters within this IMTA system, with no apparent advantage or disadvantage to growth.

Development of an In-Situ Mass Spectrometer for Stable Isotope Analysis

2003 ◽  
Author(s):  
R. T. Short ◽  
Gottfried P. Kibelka ◽  
Robert H. Byrne ◽  
David Hollander
Keyword(s):  
Stable Isotope ◽  
Mass Spectrometer ◽  
Stable Isotope Analysis ◽  
Isotope Analysis
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