Foraging depth depicts resource partitioning and contamination level in a pelagic shark assemblage: Insights from mercury stable isotopes

Besnard, Lucien; Croizier, Gaël Le; Galván‐Magaña, Felipe; Point, David; Kraffe, Edouard; Rincón, Raúl Octavio Martínez; Schaal, Gauthier

doi:10.1016/j.envpol.2021.117066

Cited by 20 publications

(25 citation statements)

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“…Furthermore, mathematical corrections to remove photochemical fractionation (Blum et al, 2013) indicate that the initial δ 202 Hg COR of MeHg in both sets of tuna, prior to photochemical demethylation, is from a similar source. These results are consistent with those of studies that showed an apparent common marine source of bioavailable MeHg for most large pelagic fish in the Pacific Ocean (Besnard et al, 2021; Blum et al, 2013). Our data suggest that precipitation (i.e., atmospheric wet deposition) is the primary Hg exposure pathway for this portion of the southern Tropical Eastern Pacific Ocean food web due to the prevalence of positive Δ 200 Hg observed in the Galápagos Marine Reserve and Ecuadorian mainland coast populations.…”

Section: Discussionsupporting

confidence: 92%

Elevated Mercury Concentrations and Isotope Signatures (N, C, Hg) in Yellowfin Tuna (Thunnus albacares) from the Galápagos Marine Reserve and Waters off Ecuador

Muñoz‐Abril

Valle

Alava

et al. 2022

Enviro Toxic and Chemistry

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We examined how dietary factors recorded by C and N influence Hg uptake in 347 individuals of yellowfin tuna (Thunnus albacares), an important subsistence resource from the Galápagos Marine Reserve (Ecuador) and the Ecuadorian mainland coast in 2015–2016. We found no differences in total Hg (THg) measured in red muscle between the two regions and no seasonal differences, likely due to the age of the fish and slow elimination rates of Hg. Our THg concentrations are comparable to those of other studies in the Pacific (0.20‐9.60 mg/kg wet wt), but a subset of individuals exhibited the highest Hg concentrations yet reported in yellowfin tuna. Mercury isotope values differed between Δ199Hg and δ202Hg in both regions (Δ199Hg = 2.86 ± 0.04‰ vs. Δ199Hg = 2.33 ± 0.07‰), likely related to shifting food webs and differing photochemical processing of Hg prior to entry into the food web. There were significantly lower values of both δ15N and δ13C in tuna from Galápagos Marine Reserve (δ15N: 8.5–14.2‰, δ13C: −18.5 to −16.1‰) compared with those from the Ecuadorian mainland coast (δ15N: 8.3–14.4‰, δ13C: −19.4 to −11.9‰), of which δ13C values suggest spatially constrained movements of tuna. Results from the pooled analysis, without considering region, indicated that variations in δ13C and δ15N values tracked changes of Hg stable isotopes. Our data indicate that the individual tuna we used were resident fish of each region and were heavily influenced by upwellings related to the eastern Pacific oxygen minimum zone and the Humboldt Current System. The isotopes C, N, and Hg reflect foraging behavior mainly on epipelagic prey in shallow waters and that food web shifts drive Hg variations between these populations of tuna. Environ Toxicol Chem 2022;41:2732–2744. © 2022 SETAC

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Section: Discussionsupporting

confidence: 92%

Elevated Mercury Concentrations and Isotope Signatures (N, C, Hg) in Yellowfin Tuna (Thunnus albacares) from the Galápagos Marine Reserve and Waters off Ecuador

Muñoz‐Abril

Valle

Alava

et al. 2022

Enviro Toxic and Chemistry

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“…Emerging compound-specific trace element analyses, such as mercury stable isotopes, can offer a great opportunity to delineate the vertical habitat of cephalopods, as already shown in sharks (Le Le Croizier G.l. et al, 2020;Besnard et al, 2021) and seabirds (Renedo et al, 2018). Indeed, when using trace elements to study individual migrations, it is important to know if there is any ontogenetic change in the diet or trophic position, because as trace elements are mostly taken up by diet (Szynkowska et al, 2018), we need to be sure to be sure that changes in trace element concentrations are in fact related to changes of habitat and not with the trophic position of cephalopods.…”

Section: Trace Elementsmentioning

confidence: 99%

“…Hence, it is important to be careful when analysing the results, especially when comparing different beak sections or beaks from different species for trace elements, sizes and maturation states (Queirós et al, 2020a). As with SIA, this limitation can be overcome with the compound specific trace elements analysis (Renedo et al, 2018;Cherel et al, 2019;Whiteman et al, 2019;Besnard et al, 2021).…”

Section: Trace Elementsmentioning

confidence: 99%

The significance of cephalopod beaks as a research tool: An update

Xavier

Golikov²,

Queirós³

et al. 2022

Front. Physiol.

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The use of cephalopod beaks in ecological and population dynamics studies has allowed major advances of our knowledge on the role of cephalopods in marine ecosystems in the last 60 years. Since the 1960’s, with the pioneering research by Malcolm Clarke and colleagues, cephalopod beaks (also named jaws or mandibles) have been described to species level and their measurements have been shown to be related to cephalopod body size and mass, which permitted important information to be obtained on numerous biological and ecological aspects of cephalopods in marine ecosystems. In the last decade, a range of new techniques has been applied to cephalopod beaks, permitting new kinds of insight into cephalopod biology and ecology. The workshop on cephalopod beaks of the Cephalopod International Advisory Council Conference (Sesimbra, Portugal) in 2022 aimed to review the most recent scientific developments in this field and to identify future challenges, particularly in relation to taxonomy, age, growth, chemical composition (i.e., DNA, proteomics, stable isotopes, trace elements) and physical (i.e., structural) analyses. In terms of taxonomy, new techniques (e.g., 3D geometric morphometrics) for identifying cephalopods from their beaks are being developed with promising results, although the need for experts and reference collections of cephalopod beaks will continue. The use of beak microstructure for age and growth studies has been validated. Stable isotope analyses on beaks have proven to be an excellent technique to get valuable information on the ecology of cephalopods (namely habitat and trophic position). Trace element analyses is also possible using beaks, where concentrations are significantly lower than in other tissues (e.g., muscle, digestive gland, gills). Extracting DNA from beaks was only possible in one study so far. Protein analyses can also be made using cephalopod beaks. Future challenges in research using cephalopod beaks are also discussed.

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“…For example, recent work by Besnard et al ( 2021 ; δ 15 N, δ 13 C, and δ 202 Hg isotopes) and Skinner, Mill, et al ( 2019 ; δ 15 N, δ 13 C, and δ 34 S isotopes) has shown the utility of three‐dimensional SIBER to investigate complex trophic strategies where two dimensions have failed. This three‐dimensional method successfully differentiated among pelagic shark trophic strategies that did not vary significantly by resource use ( δ 15 N and δ 13 C) but were characterized by depth gradients (additional δ 202 Hg isotope; Besnard et al, 2021 ), and revealed within‐species individual specializations in feeding strategies of teleost reef fish that were not detectable using just δ 15 N and δ 13 C (additional δ 34 S isotope; Skinner, Mill, et al, 2019 ). Incorporating additional isotopic information is relatively simple with the advancement of SIA instrumentation, yet examples of its utility across different environments are limited.…”

Section: Introductionmentioning

confidence: 99%

“…Including additional dimensions to SIA that are ecologically relevant offers one solution to increase understanding of isotopic (and potentially trophic) variability. For example, recent work by Besnard et al (2021;δ 15 N, δ 13 C, and δ 202 Hg isotopes) and δ 15 N, δ 13 C, and δ 34 S isotopes) has shown the utility of threedimensional SIBER to investigate complex trophic strategies where two dimensions have failed. This three-dimensional method successfully differentiated among pelagic shark trophic strategies that did not vary significantly by resource use (δ 15 N and δ 13 C) but were characterized by depth gradients (additional δ 202 Hg isotope; Besnard et al, 2021), and revealed within-species individual specializations in feeding strategies of teleost reef fish that were not detectable using resource availability, which are not detectable using only δ 15 N and δ 13 C. We recommend that researchers include δ 34 S in future aquatic food web studies.…”

Section: Introductionmentioning

confidence: 99%

Improving stable isotope assessments of inter‐ and intra‐species variation in coral reef fish trophic strategies

Cybulski

Skinner

Wan

et al. 2022

Ecology and Evolution

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Fish have one of the highest occurrences of individual specialization in trophic strategies among Eukaryotes. Yet, few studies characterize this variation during trophic niche analysis, limiting our understanding of aquatic food web dynamics. Stable isotope analysis (SIA) with advanced Bayesian statistics is one way to incorporate this individual trophic variation when quantifying niche size. However, studies using SIA to investigate trophodynamics have mostly focused on species‐ or guild‐level (i.e., assumed similar trophic strategy) analyses in settings where source isotopes are well‐resolved. These parameters are uncommon in an ecological context. Here, we use Stable Isotope Bayesian Ellipses in R (SIBER) to investigate cross‐guild trophodynamics of 11 reef fish species within an oceanic atoll. We compared two‐ ( δ 15 N and δ 13 C) versus three‐dimensional ( δ 15 N, δ 13 C, and δ 34 S) reconstructions of isotopic niche space for interpreting guild‐, species‐, and individual‐level trophic strategies. Reef fish isotope compositions varied significantly among, but also within, guilds. Individuals of the same species did not cluster together based on their isotope values, suggesting within‐species specializations. Furthermore, while two‐dimensional isotopic niches helped differentiate reef fish resource use, niche overlap among species was exceptionally high. The addition of δ 34 S and the generation of three‐dimensional isotopic niches were needed to further characterize their isotopic niches and better evaluate potential trophic strategies. These data suggest that δ 34 S may reveal fluctuations in resource availability, which are not detectable using only δ 15 N and δ 13 C. We recommend that researchers include δ 34 S in future aquatic food web studies.

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Foraging depth depicts resource partitioning and contamination level in a pelagic shark assemblage: Insights from mercury stable isotopes

Cited by 20 publications

References 100 publications

Elevated Mercury Concentrations and Isotope Signatures (N, C, Hg) in Yellowfin Tuna (Thunnus albacares) from the Galápagos Marine Reserve and Waters off Ecuador

Elevated Mercury Concentrations and Isotope Signatures (N, C, Hg) in Yellowfin Tuna (Thunnus albacares) from the Galápagos Marine Reserve and Waters off Ecuador

The significance of cephalopod beaks as a research tool: An update

Improving stable isotope assessments of inter‐ and intra‐species variation in coral reef fish trophic strategies

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