Stable isotope analysis as a tool for elasmobranch conservation research: a primer for non-specialists

2012 ◽  
Vol 63 (7) ◽  
pp. 635 ◽  
Author(s):  
D. S. Shiffman ◽  
A. J. Gallagher ◽  
M. D. Boyle ◽  
C. M. Hammerschlag-Peyer ◽  
N. Hammerschlag

Many elasmobranch species are undergoing population declines on a global scale; however, implementation of effective conservation and management strategies is hindered, to a large extent, by a lack of sufficient data on diet, life history and behaviour. This work is a primer of how stable isotope analysis can be used as a cost-effective, relatively simple tool for examining resource use patterns (e.g. diet, habitat) and generating relevant data in support of science-based elasmobranch conservation and management. Specifically, isotopes can resolve the feeding niches of elasmobranchs, detect ontogenetic trophic shifts and calculate relative diet breadth of different species. Stable isotope analysis can also be employed to investigate the extent of anthropogenic impacts on diet or to infer the source of toxins affecting elasmobranchs. Additionally, this tool can be used to study migration patterns and habitat usage. Depending on the tissue analysed, this technique can also be non-lethal and minimally invasive. The limitations of stable isotope analysis are discussed, and recommendations for future work are presented.

2018 ◽  
Vol 66 (4) ◽  
pp. 261 ◽  
Author(s):  
J. F. Ocock ◽  
K. J. Brandis ◽  
B. J. Wolfenden ◽  
K. M. Jenkins ◽  
S. Wassens

Larval amphibians (tadpoles) are an important link in aquatic food webs, as they can be highly abundant consumers and prey for a wide variety of predators. Most tadpoles are considered omnivores, predominately grazing on algae, detritus and macrophytes, though recent work has identified greater plasticity and breadth in diet than previously considered. We used gut content and stable isotope analysis (SIA) in a baseline study to determine the important dietary items (ingested material) and food sources (assimilated material) for tadpoles of two abundant generalist frog species in regulated floodplain wetlands of the Murrumbidgee River, south-east Australia. We identified a wide variety of dietary items in the gut contents, including whole microcrustaceans, filamentous algae and macrophytes. The composition of several ingested food items was correlated with their availability in each wetland. However, SIA identified biofilm as the food source most consistently assimilated across several wetlands, though microcrustaceans and algae contributed when abundant. Biofilm is likely the most important basal food item for tadpoles in floodplain wetlands because it is ubiquitous and has a high nutritional quality. Identifying important food sources is a crucial step towards developing management strategies for promoting tadpole recruitment in regulated wetlands.


Ecologies ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 187-202
Author(s):  
Waylon Hiler ◽  
Stanley E. Trauth ◽  
Benjamin Wheeler ◽  
Aimee Jimenez ◽  
Milica Radanovic ◽  
...  

Ozark hellbenders (Cryptobranchus alleganiensis bishopi) have undergone marked population declines across their entire distribution. A variety of ecological life history research has been conducted to determine the cause(s) of the declines. Historically, hellbender diet studies used stomach content examination methods; however, alternative approaches such as less intrusive stable isotope analyses are now options for researchers. The goals of our study were to conduct stable isotope analysis on live and formalin-preserved museum specimen Ozark hellbender tissues to identify diet composition in the Eleven Point and Spring rivers, Arkansas. Also, we used stable isotope analysis to investigate if Spring River hellbender diets have changed over time. We sampled fish, live hellbenders (non-destructively), and formalin-preserved hellbender tissues from museum collections for stable isotope analysis. We sampled crayfish for assemblage composition and stable isotope analysis. The results of our stable isotope study revealed three main findings: (1) there were no statistically significant differences between hellbender δ13C and δ15N values among sites and hellbender stable C and N isotopes were correlated with body length; (2) traditional δ13C versus δ15N bi-plots and trophic discrimination values did not provide complete discernment in hellbender diets; however, Bayesian MixSIAR models revealed hellbenders to be generalists, and (3) the use of δ13C and δ15N values adjusted historic formalin-fixed and ethanol preserved hellbenders matched well with current crayfish and fish stable isotope values based on Bayesian MixSIAR models. These findings provide important diet information and a possible tool to examine dietary patterns from preserved specimens that may be used for hellbender conservation and management.


2019 ◽  
Vol 97 (9) ◽  
pp. 763-772 ◽  
Author(s):  
Jacob Burbank ◽  
Mary Finch ◽  
D. Andrew R. Drake ◽  
Michael Power

Niche specificity can predispose species to population declines during periods of resource limitation, yet trophic niche specificity is poorly known for many small-bodied freshwater fishes. Applying a two-tiered approach involving stomach content and stable isotope analyses, we examined the diet and trophic niche of the threatened eastern sand darter (Ammocrypta pellucida (Putnam, 1863)) and co-occurring fishes in the Thames River, Ontario, Canada. As with previous studies, stomach content analysis revealed that eastern sand darter consumed a variety of benthic organisms including Chironomidae, Cladocera, Ostracoda, Oligochaeta, and Ephemeroptera; however, proportional contributions of prey groups differed based on stable isotope analysis, highlighting the potential for seasonal variation in prey consumption. Despite evidence of a generalist strategy, stable isotope analysis indicated eastern sand darter exhibited a relatively narrow trophic niche relative to co-occurring fishes. Trophic niche overlap was relatively minor between eastern sand darter and drift-feeding fishes (spotfin shiner (Cyprinella spiloptera (Cope, 1867)), emerald shiner (Notropis atherinoides Rafinesque, 1818), and buffalo sp. (genus Ictiobus Rafinesque, 1820)), but was more evident between eastern sand darter and benthic and benthopelagic fishes (johnny darter (Etheostoma nigrum Rafinesque, 1820) and blackside darter (Percina maculata (Girard, 1859))), indicating that competition with these species may be more likely during periods of prey scarcity.


2003 ◽  
Author(s):  
R. T. Short ◽  
Gottfried P. Kibelka ◽  
Robert H. Byrne ◽  
David Hollander

2017 ◽  
Author(s):  
Peter Mortensen ◽  
◽  
Nathan D. Stansell ◽  
Byron A. Steinman ◽  
Gilles Y. Brocard ◽  
...  

Author(s):  
Andreas Hilkert ◽  
John K. Böhlke ◽  
Stanley J. Mroczkowski ◽  
Kyle L. Fort ◽  
Konstantin Aizikov ◽  
...  

2021 ◽  
pp. 1-24
Author(s):  
Petra Vaiglova ◽  
John Coleman ◽  
Charlotte Diffey ◽  
Vasiliki Tzevelekidi ◽  
Melanie Fillios ◽  
...  

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