Radiocarbon in ecology: Insights and perspectives from aquatic and terrestrial studies

Larsen, Thomas; Yokoyama, Yūsuke; Fernandes, Ricardo

doi:10.1111/2041-210x.12851

Cited by 33 publications

(24 citation statements)

References 77 publications

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“…One advantage of the isotope tracking method is that it can reveal migration routes of individual animals over a prolonged timescale (the timescale of bone growth). Although the spatial resolution of the method depends on the spatial scale of isotopic gradients among habitats, the use of additional isoscapes based on radiocarbon content (Larsen et al 2018) or neodymium stable isotope ratios (Saitoh et al 2018) could help enable finer‐scale determinations of fish migration routes.…”

Section: Discussionmentioning

confidence: 99%

Tracking long‐distance migration of marine fishes using compound‐specific stable isotope analysis of amino acids

et al. 2020

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The long-distance migrations by marine fishes are difficult to track by field observation. Here, we propose a new method to track such migrations using stable nitrogen isotopic composition at the base of the food web (d 15 N Base ), which can be estimated by using compound-specific isotope analysis. d 15 N Base exclusively reflects the d 15 N of nitrate in the ocean at a regional scale and is not affected by the trophic position of sampled organisms. In other words, d 15 N Base allows for direct comparison of isotope ratios between proxy organisms of the isoscape and the target migratory animal. We initially constructed a d 15 N Base isoscape in the northern North Pacific by bulk and compound-specific isotope analyses of copepods (n = 360 and 24, respectively), and then we determined retrospective d 15 N Base values of spawning chum salmon (Oncorhynchus keta) from their vertebral centra (10 sections from each of two salmon). We then estimated the migration routes of chum salmon during their skeletal growth by using a state-space model. Our isotope tracking method successfully reproduced a known chum salmon migration route between the Okhotsk and Bering seas, and our findings suggest the presence of a new migration route to the Bering Sea Shelf during a later growth stage.

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Section: Discussionmentioning

confidence: 99%

Tracking long‐distance migration of marine fishes using compound‐specific stable isotope analysis of amino acids

et al. 2020

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“…In wild populations, informative priors, such as from feeding, prey abundance, or gut content observations, will improve model performance. Isotopically similar sources can also be grouped and, as in this study, additional conservative (minimally discriminated) tracers such as AA d 15 N and D 14 C added to models to increase isotopic distinction of diet differences between individuals (e.g., Larsen et al 2018). The output from uninformed, undetermined mixing models should be interpreted with great caution.…”

Section: Implications For Mixing Model Inferencesmentioning

confidence: 99%

Enhancing insights into foraging specialization in the world's largest fish using a multi‐tissue, multi‐isotope approach

Wyatt

Matsumoto

Chikaraishi

et al. 2019

Ecological Monographs

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Intra‐species variability in foraging strategies may be common, which has significant implications for efforts to understand and manage enigmatic species like the whale shark Rhincodon typus. The ecological relevance of differences in tissue isotopes within and between individuals in the context of foraging however depends on understanding tissue turnover times and carbon (Δ13C) and nitrogen (Δ15N) discrimination, which can vary with physiology, metabolism, and diet quality. Here, we examine isotope dynamics in captive R. typus as a basis for enhanced ecological insights into wild populations of the world's largest fish and other enigmatic species. A variable diet, principally consisting of two krill (Euphausia pacifica and Euphausia superba) provided an average of 48 ± 20 MJ/d (mean ± SD), or 2.7 ± 1.3 times basal metabolic requirements. On this diet, in agreement with allometric relationships, large body sizes (3,000–4,000 kg) were matched by slow plasma and cartilage turnover rates (empirically derived as 9 months and 3 yr, respectively), which provide tissue‐specific limits on the timescales over which we can isotopically detect diet changes in this species. Average diet‐to‐tissue discrimination showed significant variation between tissues (plasma and cartilage), and among growing and fasting individuals (Δ13C range, 1.5 to 5.5‰; Δ15N range, −0.1 to 2.9‰). Assimilation rates increased with temperature and were higher for the smaller E. pacifica (15 ± 2 mm) than E. superba (48 ± 2 mm). Growth significantly lowered both Δ15Nplasma and Δ15Ncartilage, with inappetence markedly reducing Δ15Nplasma and Δ13Cplasma, as well as significantly altering blood biochemistry. Captive findings facilitated the first robust multi‐tissue growth‐ and nutrition‐corrected isotope analysis of a wild R. typus population, suggesting individual foraging specialization on low trophic level mid‐ocean or coastal prey. Long‐term fasting during ocean‐basin‐scale migrations may be common and such metabolic effects should be carefully quantified when isotopically assessing intra‐species foraging differences. The metabolically constrained multi‐tissue, multi‐isotope approach described can facilitate ecological insights that are indispensable for effective conservation and management of globally threatened, but poorly understood, species by identifying differences in key foraging areas and target prey within and between individuals.

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“…The use of δ 13 C for evaluating ammocoete nutrition appears to be further confounded by factors potentially unique to ammocoetes (Evans & Bauer, 2016a). In contrast to δ 13 C, naturally occurring radiocarbon ( 14 C, as Δ 14 C) is often better at source discrimination due to its much larger dynamic range (10 2 -10 3 ‰) compared to δ 13 C and δ 15 N (at most 10-20‰) in natural systems; in addition, Δ 14 C can establish the ages of the materials used to support consumer nutrition Larsen, Yokoyama, & Fernandes, 2018). Recent work using Δ 14 C has found consumer biomass in aquatic ecosystems is supported in part, and in rare cases entirely, from highly aged plant biomass produced in the distant past (10 2 -10 4 years B.P; Guillemette, Bianchi, & Spencer, 2017).…”

mentioning

confidence: 99%

Radioisotope and stable isotope ratios (Δ¹⁴C, δ¹⁵N) suggest larval lamprey growth is dependent on both fresh and aged organic matter in streams

Evans

Bellamy

Bauer

2018

Ecology of Freshwater Fish

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Lampreys have a complex life cycle which includes a multi‐year infaunal larval stage (ammocoete). Gut content analysis has generally identified detritus (i.e., unidentifiable organic matter) as the major dietary component to ammocoetes, though algae can also be important. However, gut content preserves only a snapshot of the animal's diet and does not reflect assimilated material. In order to better characterise the nutritional sources supporting ammocoete growth, we analysed ammocoete body tissue and potential dietary sources at two streams using natural Δ14C and δ15N to estimate time‐integrated nutritional support. Bayesian isotope mixing models revealed differences in the importance of sources supporting ammocoetes between sites. Ammocoetes from a stream in a mixed land usage area (~50% agriculture, ~40% forest and ~10% developed) were primarily supported (mean: ~50%) by fresh terrestrial organic matter but were also supported by substantial contributions (mean: ~30%) by aged organic matter (AOM) and autochthonous material (algae; mean ~20%). In a predominantly forested (~90%) headwater stream, different modelling scenarios (uninformed or informed priors) suggested that algal support of ammocoete nutrition ranged from 7% to 45%. However, the model relying on informed priors developed from gut content analysis produced the low estimates, suggesting these were more reliable. When algae were a minor component of the nutrition at the forested site, ammocoetes were highly dependent on AOM (83 ± 26%; mean ± SD). Based on these findings, ammocoete growth and development are predicted to be strongly influenced by both land use and the availability of allochthonous and autochthonous materials of varying ages within streams.

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Radiocarbon in ecology: Insights and perspectives from aquatic and terrestrial studies

Cited by 33 publications

References 77 publications

Tracking long‐distance migration of marine fishes using compound‐specific stable isotope analysis of amino acids

Tracking long‐distance migration of marine fishes using compound‐specific stable isotope analysis of amino acids

Enhancing insights into foraging specialization in the world's largest fish using a multi‐tissue, multi‐isotope approach

Radioisotope and stable isotope ratios (Δ¹⁴C, δ¹⁵N) suggest larval lamprey growth is dependent on both fresh and aged organic matter in streams

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Radiocarbon in ecology: Insights and perspectives from aquatic and terrestrial studies

Cited by 33 publications

References 77 publications

Tracking long‐distance migration of marine fishes using compound‐specific stable isotope analysis of amino acids

Tracking long‐distance migration of marine fishes using compound‐specific stable isotope analysis of amino acids

Enhancing insights into foraging specialization in the world's largest fish using a multi‐tissue, multi‐isotope approach

Radioisotope and stable isotope ratios (Δ14C, δ15N) suggest larval lamprey growth is dependent on both fresh and aged organic matter in streams

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Radioisotope and stable isotope ratios (Δ¹⁴C, δ¹⁵N) suggest larval lamprey growth is dependent on both fresh and aged organic matter in streams