Analysis of narwhal tusks reveals lifelong feeding ecology and mercury exposure

Dietz, Runé; Desforges, Jean-Pierre; Rigét, Frank; Aubail, Aurore; Garde, Eva; Drimmie, R.J.; Heide‐Jørgensen, Mads Peter; Sonne, Christian

doi:10.1016/j.cub.2021.02.018

Cited by 22 publications

(29 citation statements)

References 47 publications

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“…shown in either δ 13 C or δ 15 N profiles of 23 individuals. While present, autocorrelation is a consistent, inherent feature of these longitudinal data that have been similarly analyzed using standard ellipse by other researchers (e.g., Dietz et al 2021). Individual and pooled (by period and by sex) isotopic niche breadths were calculated using standard ellipse area (SEA) with correction for small sample size (SEA c ) using the R package SIBER (Jackson et al, 2011).…”

Section: Discussionmentioning

confidence: 85%

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Isotopic (δ¹⁵N and δ¹³C) profiles in dentine indicate sex differences and individual variability in resource use among narwhals (Monodon monoceros)

Zhao

Davoren

Matthews

et al. 2022

Marine Mammal Science

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While the impact of ecological changes on Arctic marine mammals remains largely unknown, quantifying variability in resource use among conspecifics can serve as an indication of adaptive plasticity and help assess species vulnerability to climate-induced changes. We measured withintooth δ 15 N and δ 13 C profiles of narwhals (Monodon monoceros) sampled 35 years apart from Baffin Bay, Nunavut, Canada, to evaluate intrapopulation variation in narwhal resource use. Narwhal dentine δ 15 N and δ 13 C were lower post-1983 (n = 7) by 0.83‰ and 0.52‰, respectively, compared to pre-1983 (n = 13), but isotopic niche breadth increased from 0.95‰ 2 to 1.12‰ 2 . Between sexes, the isotopic niche of males expanded from pre-1983 to post-1983 while that of females decreased, which may indicate increased flexibility in resource use for males and the opposite for females. Additional isotopic variation among narwhals (n = 23) suggests individual differences in diet composition and/or foraging location during both periods.Individual isotopic niches ranged between 0.08‰ 2 and 2.27‰ 2 , where a larger isotopic niche likely indicates more variable foraging strategies over time. Narwhal as a species is considered vulnerable to ecosystem change; however, the variability in resource use between sexes and among

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Section: Discussionmentioning

confidence: 85%

“…Sequential SIA of each GLG within a tooth provides information on diet at the time each GLG is formed and, thus, a chronological life record of resource use for individual whales (e.g., Dietz et al, 2021;Newsome, Etnier, et al, 2009).…”

mentioning

confidence: 99%

Isotopic (δ¹⁵N and δ¹³C) profiles in dentine indicate sex differences and individual variability in resource use among narwhals (Monodon monoceros)

Zhao

Davoren

Matthews

et al. 2022

Marine Mammal Science

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“…Differences in isotopic composition across tusk layers have been reported [19]; however, our sampling strategy did not target a specific layer, but rather sampled a chunk of tusk comprising several layers, and hence reflected average δ 13 C and δ 15 N across several years.…”

Section: Discussionmentioning

confidence: 99%

“…Due to the smaller size of the embedded tooth compared to the tusk, its isotopic composition could still present higher δ 15 N due to the suckling effect [18,20]. Differences in isotopic composition across tusk layers have been reported [19]; however, our sampling strategy did not target a specific layer, but rather sampled a chunk of tusk comprising several layers, and hence reflected average δ 13 C and δ 15 N across several years. Because of this sampling strategy, the correction factors generated in this study are applicable to samples collected in a similar manner.…”

Section: Discussionmentioning

confidence: 99%

Combining δ¹³C and δ¹⁵N from bone and dentine in marine mammal palaeoecological research: insights from toothed whales

Rey‐Iglesia

Wilson

Routledge

et al. 2021

Preprint

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Rationale Stable carbon (δ13C) and nitrogen (δ15N) isotope compositions of bone and dentine collagen extracted from subfossil specimens of extinct and extant mammalian species have been widely used to study the paleoecology of past populations. Due to possible systematic differences in stable isotope values between bone and dentine, dentine values can be transformed into bone-collagen equivalent using a correction factor. This approach has been applied to terrestrial species, but correction factors specifically for marine mammals are lacking. Here, we provide correction factors to transform dentine δ13C and δ15N values into bone-collagen equivalent for two toothed whale sister species: narwhal and beluga. Methods We sampled bone and tooth dentine from the skulls of 11 narwhals and 26 belugas. In narwhals, dentine was sampled from tusk and embedded tooth; in beluga, dentine was sampled from tooth. δ13C and δ15N were measured using an elemental analyzer coupled to a continuous flow isotope ratio mass spectrometer. Intraindividual bone and dentine isotopic compositions were used to calculate correction factors for each species, and to translate dentine isotopic values into bone-collagen equivalent. Results Our analysis revealed differences in δ13C and δ15N between bone and dentine. In narwhals, we found (i) lower average δ13C in bone compared with dentine from tusk and embedded tooth; (ii) no difference in dentine δ13C between tusk and embedded tooth; (iii) lower average δ15N in bone compared with dentine, with the highest values found in embedded tooth. For belugas, we also detected lower δ13C and δ15N in bone compared with tooth dentine. Conclusions Based on our analysis, we provide bone/dentine correction factors for narwhals (both at species and population level), and for belugas. The correction factors, when applied to dentine δ13C and δ15N values, enable the combined analysis of stable isotope data from bone and dentine.

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“…As shown at the scale of the northeast Pacific water body (EA 6), sea water SI composition can be tracked to large spatio-temporal scales and may be tested for long-term or seasonal SI trajectories in rain and snowfall (Aizen et al, 2005;Tian et al, 2018), or ice (Schotterer et al, 1997;van Trigt et al, 2002;Werner et al, 2018). Other tracers are also increasingly used in association with SI, such as contaminants (Dietz et al, 2004(Dietz et al, , 2021 or fatty acids (Madgett et al, 2019), and the absence of limitation in the number of dimensions supporting SITA constitutes an important strength to improve the analysis of such complex multivariate datasets. As experimental studies involve very controlled protocols, SITA metrics can also be particularly relevant to depict experimental trajectories (EA3).…”

Section: Exporting Trajectory Analysis To Other Kinds Of Ecological Datamentioning

confidence: 99%

Stable Isotope Trajectory Analysis (SITA): A new approach to quantify and visualize dynamics in stable isotope studies

Sturbois

Cáceres

Desroy

et al. 2022

Ecological Monographs

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Analysis of narwhal tusks reveals lifelong feeding ecology and mercury exposure

Cited by 22 publications

References 47 publications

Isotopic (δ¹⁵N and δ¹³C) profiles in dentine indicate sex differences and individual variability in resource use among narwhals (Monodon monoceros)

Isotopic (δ¹⁵N and δ¹³C) profiles in dentine indicate sex differences and individual variability in resource use among narwhals (Monodon monoceros)

Combining δ¹³C and δ¹⁵N from bone and dentine in marine mammal palaeoecological research: insights from toothed whales

Stable Isotope Trajectory Analysis (SITA): A new approach to quantify and visualize dynamics in stable isotope studies

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Analysis of narwhal tusks reveals lifelong feeding ecology and mercury exposure

Cited by 22 publications

References 47 publications

Isotopic (δ15N and δ13C) profiles in dentine indicate sex differences and individual variability in resource use among narwhals (Monodon monoceros)

Isotopic (δ15N and δ13C) profiles in dentine indicate sex differences and individual variability in resource use among narwhals (Monodon monoceros)

Combining δ13C and δ15N from bone and dentine in marine mammal palaeoecological research: insights from toothed whales

Stable Isotope Trajectory Analysis (SITA): A new approach to quantify and visualize dynamics in stable isotope studies

Contact Info

Product

Resources

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Isotopic (δ¹⁵N and δ¹³C) profiles in dentine indicate sex differences and individual variability in resource use among narwhals (Monodon monoceros)

Isotopic (δ¹⁵N and δ¹³C) profiles in dentine indicate sex differences and individual variability in resource use among narwhals (Monodon monoceros)

Combining δ¹³C and δ¹⁵N from bone and dentine in marine mammal palaeoecological research: insights from toothed whales