Simple biopsy modification to collect muscle samples from free-swimming sharks

Meyer, Lauren; Fox, Andrew; Huveneers, Charlie

doi:10.1016/j.biocon.2018.10.024

Cited by 11 publications

(9 citation statements)

References 25 publications

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“…Free-swimming white sharks were attracted with baits (Thunnus albacares) near the scientific boat. Samples (dermis and muscle) were taken using a biopsy probe (1 cm diameter) targeting the tissue directly below the dorsal fin . The same device was used to collect NES hair on one of the island’s beaches.…”

Section: Methodsmentioning

confidence: 99%

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The Twilight Zone as a Major Foraging Habitat and Mercury Source for the Great White Shark

Croizier

Lorrain

Sonke

et al. 2020

Environ. Sci. Technol.

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The twilight zone contains the largest biomass of the world’s ocean. Identifying its role in the trophic supply and contaminant exposure of marine megafauna constitutes a critical challenge in the context of global change. The white shark (Carcharodon carcharias) is a threatened species with some of the highest concentrations of neurotoxin methylmercury (MeHg) among marine top predators. Large white sharks migrate seasonally from coastal habitats, where they primarily forage on pinnipeds, to oceanic offshore habitats. Tagging studies suggest that while offshore, white sharks may forage at depth on mesopelagic species, yet no biochemical evidence exists. Here, we used mercury isotopic composition to assess the dietary origin of MeHg contamination in white sharks from the Northeast Pacific Ocean. We estimated that a minimum of 72% of the MeHg accumulated by white sharks originates from the consumption of mesopelagic prey, while a maximum of 25% derives from pinnipeds. In addition to highlighting the potential of mercury isotopes to decipher the complex ecological cycle of marine predators, our study provides evidence that the twilight zone constitutes a crucial foraging habitat for these large predators, which had been suspected for over a decade. Climate change is predicted to expand the production of mesopelagic MeHg and modify the mesopelagic biomass globally. Considering the pivotal role of the twilight zone is therefore essential to better predict both MeHg exposure and trophic supply to white sharks, and effectively protect these key vulnerable predators.

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Section: Methodsmentioning

confidence: 99%

“…Samples (dermis and muscle) were taken using a biopsy probe (1 cm diameter) targeting the tissue directly below the dorsal fin. 52 The same device was used to collect NES hair on one of the island's beaches. The biopsy probe was cleaned and rinsed with alcohol before and between samples.…”

Section: ■ Introductionmentioning

confidence: 99%

The Twilight Zone as a Major Foraging Habitat and Mercury Source for the Great White Shark

Croizier

Lorrain

Sonke

et al. 2020

Environ. Sci. Technol.

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“…Furthermore, liver was not assessed within this study as the FA profiles are likely heavily influenced by physiological factors (including migration, buoyancy, diet, pregnancy, energy availability [Ballantyne, ; Pethybridge, Daley, Virtue, Butler, et al., ; Pethybridge, Daley, Virtue, & Nichols, ]), potentially confounding the influence of abiotic and biotic drivers of interest. Additionally, sufficient muscle for FA analysis can be taken from most chondrichthyans with sub‐lethal biopsies (Meyer, Fox, & Huveneers, ; Meyer et al., ), unlike obtaining liver samples. Studies referring to unnatural diets (e.g., in captivity [Beckmann, Mitchell, Seuront, et al., ; Beckmann, Mitchell, Stone, et al., ]) were excluded from the analysis.…”

Section: Methodsmentioning

confidence: 99%

Abiotic and biotic drivers of fatty acid tracers in ecology: A global analysis of chondrichthyan profiles

et al. 2019

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The use of fatty acid (FA) tracers is a growing tool in trophic ecology, yet FA profiles are driven by a number of abiotic and biotic parameters, making interpretation and appropriate use confusing for ecologists. We undertook a global analysis, compiling FA profiles of 106 chondrichthyan (shark, ray and chimaera) populations, as a model to test the utility of FA profiles to partition a priori trophic guilds, phylogeny, water temperature and habitats. Individual FAs characterizing these four factors were identified, promoting the use of these FAs as ecological tracers across taxa. Habitat type was linked to five FAs: 16:0, 18:0 and biologically essential 22:6ω3 (indicative of the deep sea), 20:5ω3 (non‐complex demersal and deep‐sea demersal) and 20:4ω6 (reef and brackish water). Temperature was a key driver of four FAs (22:5ω6, 22:4ω6, 20:1ω9 and 20:5ω3), while trophic guild and phylogeny were important drivers of two pairs of FA tracers (18:0 and 20:5ω3; 20:1ω9 and 18:1ω9, respectively). This analysis provides a novel understanding of the biological and ecological information that can be inferred from FA profiles and further validates the use of FAs as tracers to investigate the trophic ecology of chondrichthyans. Future research should prioritize ex situ studies to further disentangle the influence of factors across taxa and tissue types, quantify biomodification, enabling the use of quantitative methods for diet determination and further develop ‘FATscapes’ to elucidate fine‐scale trophic geography and climate variability. Additionally, the creation of a taxonomically inclusive FA data repository will enable further meta‐analyses. A plain language summary is available for this article.

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“…To date, elasmobranch SIA studies have focused primarily on muscle tissue, partly as it can be extracted non-lethally but also as it has additional uses, e.g., for investigating stock structure and physiology (Benavides et al, 2011;Meyer et al, 2018). While the use of other non-lethal tissues such as fin, whole blood, or its components [plasma and red blood cells (RBC)] is increasing, few SIA studies utilize multiple tissues, despite the additional temporal information they can convey.…”

Section: Introductionmentioning

confidence: 99%

A Multi-Tissue, Multi-Species Assessment of Lipid and Urea Stable Isotope Biases in Mesopredator Elasmobranchs

et al. 2022

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The application of stable isotope analysis (SIA) is increasing in elasmobranch trophic ecology, but inconsistency remains in terms of the tissue pre-treatment methods chosen to remove biases introduced by lipids and urea. SIA of a range of non-lethally extracted tissues from a diverse group of elasmobranchs, including mesopredators, is increasing, yet most studies assume that isotope biases from lipid and urea are the same across tissues and species. To determine tissue- and species-specific isotope biases across treatment methods, three tissues and their components [muscle, fin, and blood separated into plasma and red blood cells (RBC)] were non-lethally extracted from three species of mesopredatory elasmobranchs and subjected to one of three treatment methods: (1) deionized water rinse [DW], (2) chloroform/methanol lipid extraction [LE], or (3) deionized water followed by chloroform/methanol [DW+LE]. In muscle δ13C, all treatments displayed minimal variation (∼ 0‰) but large increases in δ15N (∼ 1‰) indicated urea removal. Fin δ13C values decreased with DW but increased with LE and DW+LE, whilst all treatments increased fin δ15N (∼ 0.5‰), suggesting removal of both lipid and urea. Plasma δ13C and δ15N displayed high individual variation; large decreases in δ13C (∼−0.8‰) across all treatments, but particularly DW, suggested the removal of 13C-enriched compounds while a small increase in δ15N (∼ 0.2‰) suggested minimal urea removal. In RBC, all treatments showed small δ13C declines (∼−0.5‰), with no difference in δ15N, suggesting minimal removal of 13C-enriched compounds and urea. For muscle and fin, DW+LE is the most appropriate treatment to standardize δ13C and δ15N consistently across individuals and tissues. The large individual variation in treatment effects on plasma suggests it is unsuitable for current treatment methods. Consistent treatment effects for RBC allow for DW+LE standardization, however, broader species-specific effects are unknown. The importance of treatment choice for accurately estimating prey contributions to elasmobranch diet was highlighted using Bayesian stable isotope mixing model comparisons, with prey contributions varying significantly among treatments. This variability suggests that ecological inferences from elasmobranch tissue SIA are not robust to different treatment methods. It is recommended that studies employ standardized corrections using a combined DW+LE treatment where applicable.

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Simple biopsy modification to collect muscle samples from free-swimming sharks

Cited by 11 publications

References 25 publications

The Twilight Zone as a Major Foraging Habitat and Mercury Source for the Great White Shark

The Twilight Zone as a Major Foraging Habitat and Mercury Source for the Great White Shark

Abiotic and biotic drivers of fatty acid tracers in ecology: A global analysis of chondrichthyan profiles

A Multi-Tissue, Multi-Species Assessment of Lipid and Urea Stable Isotope Biases in Mesopredator Elasmobranchs

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