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Strong EA, Crowley SL, Newth JL, O'Brien MF, Colom RL, Davis SA, Cromie RL, Bearhop S, McDonald RA. Spatial and temporal variation in the prevalence of illegal lead shot in reared and wild mallards harvested in England. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024:124756. [PMID: 39153538 DOI: 10.1016/j.envpol.2024.124756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 08/13/2024] [Accepted: 08/14/2024] [Indexed: 08/19/2024]
Abstract
The use of lead shotgun ammunition for shooting wildfowl has been restricted in England since 1999, but surveys finding lead shot in harvested birds show compliance with regulations has been low. Following the announcement in 2020 of a voluntary transition from lead to non-lead shot by UK shooting organizations, we investigated spatiotemporal variation in the composition of ammunition used for shooting mallards Anas platyrhynchos. We collected 176 harvested mallards during the 2021/22 shooting season and analyzed recent shot extracted from carcasses to determine shot composition. Using a separate collection of ducks of known provenance, we used stable isotope analysis as a means of differentiating captive-reared from wild mallards. This allowed us to understand how compliance might vary between driven game shooters, characterized by shooting birds that are flushed over a stationary line of shooters, and who primarily harvest captive-reared and released ducks, and wild duck shooters. Of 133 mallards containing recent shot, 92 (69%) had been illegally shot with lead. Analysis of this and five comparable surveys between 2001 and 2019 indicates regional and temporal variation in lead shot presence in England. In the North West and West Midlands, the likelihood of mallards containing lead shot decreased significantly over time, but no other regions showed significant changes. The use of non-lead shot types varied over time, with increases in steel shot use approximately matched by declines in bismuth shot. Mallards likely to be reared were more likely to have been shot with lead (75%) than those likely to be wild (48%). This suggests the use of lead shot is more frequent among driven game shooters than wild duck shooters. In England in 2021/22, most mallards continued to be shot with lead, suggesting that neither legislation nor voluntary approaches have been effective in substantially reducing illegal use of lead shot.
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Affiliation(s)
- Emily A Strong
- University of Exeter, Penryn Campus, Penryn TR10 9FE, UK; The Wildfowl & Wetlands Trust, Slimbridge GL2 7BT, UK.
| | | | - Julia L Newth
- The Wildfowl & Wetlands Trust, Slimbridge GL2 7BT, UK
| | | | | | - Sean A Davis
- School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
| | - Ruth L Cromie
- The Wildfowl & Wetlands Trust, Slimbridge GL2 7BT, UK
| | - Stuart Bearhop
- University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
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2
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Bastos RF, Condini MV, Barbosa EF, Oliveira RL, Almeida LL, Garcia AM, Hostim-Silva M. Seeing further into the early steps of the endangered atlantic goliath grouper (Epinephelus itajara): Eye lenses high resolution isotopic profiles reveal ontogenetic trophic and habitat shifts. MARINE ENVIRONMENTAL RESEARCH 2024; 198:106517. [PMID: 38657369 DOI: 10.1016/j.marenvres.2024.106517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/12/2024] [Accepted: 04/15/2024] [Indexed: 04/26/2024]
Abstract
Estuarine mangroves are often considered nurseries for the Atlantic Goliath grouper juveniles. Yet, the contributions of different estuarine primary producers and habitats as sources of organic matter during early ontogenetic development remain unclear. Given the species' critically endangered status and protection in Brazil, obtaining biological samples from recently settled recruits in estuaries is challenging. In this study, we leveraged a local partnership with fishers and used stable isotope (C and N) profiles from the eye lenses of stranded individuals or incidentally caught by fishery to reconstruct the trophic and habitat changes of small juveniles. The eye lens grows by the apposition of protein-rich layers. Once these layers are formed, they become inert, allowing to make inferences on the trophic ecology and habitat use along the development of the individual until its capture. We used correlations between fish size and the entire eye lens size, along with estuarine baselines, to reconstruct the fish size and trophic positions for each of the lens layers obtained. We then used dominant primary producers and basal sources from mangrove sheltered, exposed estuarine and marine habitats to construct an ontogenetic model of trophic and habitat support changes since maternal origins. Our model revealed marine support before the juveniles reached 25 mm (standard length), followed by a rapid increase in reliance on mangrove sheltered sources, coinciding with the expected size at settlement. After reaching 60 mm, individuals began to show variability. Some remained primarily supported by the mangrove sheltered area, while others shifted to rely more on the exposed estuarine area around 150 mm. Our findings indicate that while mangroves are critical for settlement, as Goliath grouper juveniles grow, they can utilize organic matter produced throughout the estuary. This underscores the need for conservation strategies that focus on seascape connectivity, as protecting just one discrete habitat may not be sufficient to preserve this endangered species and safeguard its ecosystem functions.
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Affiliation(s)
- Rodrigo F Bastos
- Laboratório de Ecologia de Peixes Marinhos/LEPMAR, Departamento de Ciências Agrárias e Biológicas, CEUNES, Universidade Federal do Espírito Santo, BR-101, Km 60, Litorâneo, São Mateus, ES, 29932-540, Brazil; Programa de Pós-graduação Em Oceanografia Ambiental, Universidade Federal Do Espírito Santo - Av. Fernando Ferrari, 514 - Goiabeiras, Vitória, ES, 29075-910, Brazil.
| | - Mario V Condini
- Laboratório de Ecologia de Peixes Marinhos/LEPMAR, Departamento de Ciências Agrárias e Biológicas, CEUNES, Universidade Federal do Espírito Santo, BR-101, Km 60, Litorâneo, São Mateus, ES, 29932-540, Brazil; Programa de Pós-graduação Em Oceanografia Ambiental, Universidade Federal Do Espírito Santo - Av. Fernando Ferrari, 514 - Goiabeiras, Vitória, ES, 29075-910, Brazil
| | - Ester F Barbosa
- Laboratório de Ecologia de Peixes Marinhos/LEPMAR, Departamento de Ciências Agrárias e Biológicas, CEUNES, Universidade Federal do Espírito Santo, BR-101, Km 60, Litorâneo, São Mateus, ES, 29932-540, Brazil
| | - Rafael L Oliveira
- Laboratório de Ecologia de Peixes Marinhos/LEPMAR, Departamento de Ciências Agrárias e Biológicas, CEUNES, Universidade Federal do Espírito Santo, BR-101, Km 60, Litorâneo, São Mateus, ES, 29932-540, Brazil; Programa de Pós-Graduação Em Ciências Biológicas (Biologia Animal - PPGBAN), Departamento de Ciências Biológicas, Universidade Federal Do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, CEP: 29055-460, Vitória, ES, Brazil
| | - Lorena L Almeida
- Laboratório de Ecologia de Peixes Marinhos/LEPMAR, Departamento de Ciências Agrárias e Biológicas, CEUNES, Universidade Federal do Espírito Santo, BR-101, Km 60, Litorâneo, São Mateus, ES, 29932-540, Brazil; Instituto Meros Do Brasil, Rua Benjamin Constant 67, Conj. 1104, CEP: 80060-020, Curitiba, PR, Brazil
| | - Alexandre M Garcia
- Laboratório de Ictiologia, Instituto de Oceanografia, Universidade Federal Do Rio Grande, Av. Itália Km 8, Carreiros. 96.201-900, Rio Grande, RS, Brazil
| | - Maurício Hostim-Silva
- Laboratório de Ecologia de Peixes Marinhos/LEPMAR, Departamento de Ciências Agrárias e Biológicas, CEUNES, Universidade Federal do Espírito Santo, BR-101, Km 60, Litorâneo, São Mateus, ES, 29932-540, Brazil; Programa de Pós-graduação Em Oceanografia Ambiental, Universidade Federal Do Espírito Santo - Av. Fernando Ferrari, 514 - Goiabeiras, Vitória, ES, 29075-910, Brazil; Programa de Pós-Graduação Em Ciências Biológicas (Biologia Animal - PPGBAN), Departamento de Ciências Biológicas, Universidade Federal Do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, CEP: 29055-460, Vitória, ES, Brazil; Instituto Meros Do Brasil, Rua Benjamin Constant 67, Conj. 1104, CEP: 80060-020, Curitiba, PR, Brazil
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Carter WA, Pagano SS, Seewagen CL. The effects of diet-shifting from invertebrates towards fruit on the condition of autumn-migrant Catharus thrushes. Oecologia 2024; 204:559-573. [PMID: 38363323 DOI: 10.1007/s00442-024-05511-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 01/08/2024] [Indexed: 02/17/2024]
Abstract
Migration is an energetically challenging and risky life history stage for many animals, but could be supported by dietary choices en route, which may create opportunities to improve body and physiological condition. However, proposed benefits of diet shifts, such as between seasonally available invertebrates and fruits, have received limited investigation in free-living animals. We quantified diet composition and magnitude of autumn diet shifts over two time periods in two closely-related species of migratory songbirds on stopover in the northeastern U.S. (Swainson's thrush [Catharus ustulatus], long-distance migrant, N = 83; hermit thrush [C. guttatus], short-distance migrant, N = 79) and used piecewise structural equation models to evaluate the relationships among (1) migration timing, (2) dietary behavior, and (3) morphometric and physiological condition indices. Tissue isotope composition indicated that both species shifted towards greater fruit consumption. Larger shifts in recent weeks corresponded to higher body condition in Swainson's, but not hermit thrushes, and condition was more heavily influenced by capture date in Swainson's thrushes. Presence of "high-antioxidant" fruits in fecal samples was unrelated to condition in Swainson's thrushes and negatively related to multiple condition indices in hermit thrushes, possibly indicating the value of fruits during migration is related more to their energy and/or macronutrient content than antioxidant content. Our results suggest that increased frugivory during autumn migration can support condition, but those benefits might depend on migration strategy: a longer-distance, more capital-dependent migration strategy could require stricter regulation of body condition aided by increased fruit consumption.
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Affiliation(s)
- Wales A Carter
- Great Hollow Nature Preserve and Ecological Research Center, 225 State Route 37, New Fairfield, CT, 06812, USA.
| | - Susan Smith Pagano
- Thomas H. Gosnell School of Life Sciences, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY, 14623, USA
| | - Chad L Seewagen
- Great Hollow Nature Preserve and Ecological Research Center, 225 State Route 37, New Fairfield, CT, 06812, USA
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Carter WA, DeMoranville KJ, Trost L, Bryła A, Działo M, Sadowska ET, Bauchinger U, Pierce B, McWilliams SR. Dietary fatty acids and flight-training influence the expression of the eicosanoid hormone prostacyclin in songbirds. Comp Biochem Physiol A Mol Integr Physiol 2024; 288:111561. [PMID: 38056555 DOI: 10.1016/j.cbpa.2023.111561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 12/01/2023] [Accepted: 12/01/2023] [Indexed: 12/08/2023]
Abstract
Diet shifts can alter tissue fatty acid composition in birds, which is subsequently related to metabolic patterns. Eicosanoids, short-lived fatty acid-derived hormones, have been proposed to mediate these relationships but neither baseline concentrations nor the responses to diet and exercise have been measured in songbirds. We quantified a stable derivative of the vasodilatory eicosanoid prostacyclin in the plasma of male European Starlings (Sturnus vulgaris, N = 25) fed semisynthetic diets with either high (PUFA) or low (MUFA) amounts of n6 fatty acid precursors to prostacyclin. Plasma samples were taken from each bird before, immediately after, and two days following a 15-day flight-training regimen that a subset of birds (N = 17) underwent. We found elevated prostacyclin levels in flight-trained birds fed the PUFA diet compared to those fed the MUFA diet and a positive relationship between prostacyclin and body condition, indexed by fat score. Prostacyclin concentrations also significantly decreased at the final time point. These results are consistent with the proposed influences of precursor availability (i.e., dietary fatty acids) and regulatory feedback associated with exercise (i.e., fuel supply and inflammation), and suggest that prostacyclin may be an important mediator of dietary influence on songbird physiology.
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Affiliation(s)
- Wales A Carter
- Department of Resources Science, University of Rhode Island, Kingston, RI, USA.
| | | | - Lisa Trost
- Department for Behavioural Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Amadeusz Bryła
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Maciej Działo
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Edyta T Sadowska
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Ulf Bauchinger
- Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | - Barbara Pierce
- Department of Biology, Sacred Heart University, Fairfield, CT, USA
| | - Scott R McWilliams
- Department of Resources Science, University of Rhode Island, Kingston, RI, USA
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Brasileiro L, Mayrink RR, Pereira AC, Costa FJV, Nardoto GB. Differentiating wild from captive animals: an isotopic approach. PeerJ 2023; 11:e16460. [PMID: 38025752 PMCID: PMC10680447 DOI: 10.7717/peerj.16460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 10/23/2023] [Indexed: 12/01/2023] Open
Abstract
Background Wildlife farming can be an important but complex tool for conservation. To achieve conservation benefits, wildlife farming should meet a variety of criteria, including traceability conditions to identify the animals' origin. The traditional techniques for discriminating between wild and captive animals may be insufficient to prevent doubts or misdeclaration, especially when labels are not expected or mandatory. There is a pressing need to develop more accurate techniques to discriminate between wild and captive animals and their products. Stable isotope analysis has been used to identify animal provenance, and some studies have successfully demonstrated its potential to differentiate wild from captive animals. In this literature review, we examined an extensive collection of publications to develop an overall picture of the application of stable isotopes to distinguish between wild and captive animals focusing on evaluating the patterns and potential of this tool. Survey methodology We searched peer-reviewed publications in the Web of Science database and the references list from the main studies on the subject. We selected and analyzed 47 studies that used δ13C, δ15N, δ2H, δ18O, and δ34S in tissues from fish, amphibians, reptiles, birds, and mammals. We built a database from the isotope ratios and metadata extracted from the publications. Results Studies have been using stable isotopes in wild and captive animals worldwide, with a particular concentration in Europe, covering all main vertebrate groups. A total of 80.8% of the studies combined stable isotopes of carbon and nitrogen, and 88.2% used at least one of those elements. Fish is the most studied group, while amphibians are the least. Muscle and inert organic structures were the most analyzed tissues (46.81% and 42.55%). δ13C and δ15N standard deviation and range were significantly higher in the wild than in captive animals, suggesting a more variable diet in the first group. δ13C tended to be higher in wild fishes and in captive mammals, birds, reptiles, and amphibians. δ15N was higher in the wild terrestrial animals when controlling for diet. Only 5.7% of the studies failed to differentiate wild and captive animals using stable isotopes. Conclusions This review reveals that SIA can help distinguish between wild and captive in different vertebrate groups, rearing conditions, and methodological designs. Some aspects should be carefully considered to use the methodology properly, such as the wild and captivity conditions, the tissue analyzed, and how homogeneous the samples are. Despite the increased use of SIA to distinguish wild from captive animals, some gaps remain since some taxonomic groups (e.g., amphibians), countries (e.g., Africa), and isotopes (e.g., δ2H, δ18O, and δ34S) have been little studied.
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Affiliation(s)
- Luiza Brasileiro
- Diretoria de Fiscalização Ambiental, Brasilia Ambiental, Brasília, DF, Brazil
- Departamento de Ecologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
| | - Rodrigo Ribeiro Mayrink
- Departamento de Ecologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
- Setor Técnico-Científico, Policia Federal, Belo Horizonte, MG, Brazil
| | - André Costa Pereira
- Departamento de Ecologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
| | | | - Gabriela Bielefeld Nardoto
- Departamento de Ecologia, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, Brazil
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Fanelli E, Da Ros Z, Menicucci S, Malavolti S, Biagiotti I, Canduci G, De Felice A, Leonori I. The pelagic food web of the Western Adriatic Sea: a focus on the role of small pelagics. Sci Rep 2023; 13:14554. [PMID: 37666876 PMCID: PMC10477188 DOI: 10.1038/s41598-023-40665-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 08/16/2023] [Indexed: 09/06/2023] Open
Abstract
The Adriatic Sea is one of the largest areas of occurrence of shared small pelagic stocks and the most fished area of the Mediterranean Sea, which is in turn one of the most exploited basins of the world. The variations in the stable isotope contents (δ15N and δ13C) were determined for three small pelagic fishes (i.e., Engraulis encrasicolus, Sardina pilchardus, and Sprattus sprattus, respectively known as anchovies, sardines and sprats) collected across the western side of the basin. Our data allowed to determine the width and features of their trophic niches, to assess potential overlap or resource partitioning among them, and likely anticipate species adaptation to future climate change scenarios. Moreover, variations in stable isotope contents were correlated to both resource availability (i.e., mesozooplankton) and environmental variables. The high productivity and in turn the high resource availability of the basin, especially in the northern part, resulted in favor of the resource partitioning that occurs in each sub-area of the Adriatic Sea among the three species. Medium-sized specimens of the three species mostly fed on small zooplankton, while adult sprats relied on large copepods and those of sardines and anchovies also consumed large portion of phytoplankton, confirming the high trophic plasticity of these two dominants small pelagic species. However, considering that anchovies have the greatest degree of trophic diversity compared with the other two species, they could be the most adapted to changing feeding conditions. The increase in sea temperatures that are reducing primary production and in turn zooplankton abundances, coupled with even more frequent extreme meteorologic events could exacerbate the competition for trophic resources among pelagic mesopredators, and could lead to more notable stocks' fluctuations and unpredictable wasp-waist effects.
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Affiliation(s)
- E Fanelli
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131, Ancona, Italy.
- Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, Italy.
- Institute for Marine Biological Resources and Biotechnologies (IRBIM), National Research Council (CNR), Largo Fiera Della Pesca, 60125, Ancona, Italy.
| | - Z Da Ros
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Via Brecce Bianche, 60131, Ancona, Italy
| | - S Menicucci
- Institute for Marine Biological Resources and Biotechnologies (IRBIM), National Research Council (CNR), Largo Fiera Della Pesca, 60125, Ancona, Italy
- Alma Mater Studiorum, Università di Bologna, Via Zamboni, 33, 40126, Bologna, Italy
| | - S Malavolti
- Institute for Marine Biological Resources and Biotechnologies (IRBIM), National Research Council (CNR), Largo Fiera Della Pesca, 60125, Ancona, Italy
| | - I Biagiotti
- Institute for Marine Biological Resources and Biotechnologies (IRBIM), National Research Council (CNR), Largo Fiera Della Pesca, 60125, Ancona, Italy
| | - G Canduci
- Institute for Marine Biological Resources and Biotechnologies (IRBIM), National Research Council (CNR), Largo Fiera Della Pesca, 60125, Ancona, Italy
| | - A De Felice
- Institute for Marine Biological Resources and Biotechnologies (IRBIM), National Research Council (CNR), Largo Fiera Della Pesca, 60125, Ancona, Italy
| | - I Leonori
- Institute for Marine Biological Resources and Biotechnologies (IRBIM), National Research Council (CNR), Largo Fiera Della Pesca, 60125, Ancona, Italy
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Marrack LC, Beavers SC. Anchialine pool shrimp (Halocaridina rubra) as an indicator of sewage in coastal groundwater ecosystems on the island of Hawai'i. PLoS One 2023; 18:e0290658. [PMID: 37651382 PMCID: PMC10470924 DOI: 10.1371/journal.pone.0290658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Accepted: 08/03/2023] [Indexed: 09/02/2023] Open
Abstract
Groundwater is a primary pathway for wastewater and other pollutants to enter coastal ecosystems worldwide. Sewage associated pathogens, pharmaceuticals, and other emerging contaminants pose potential risks to marine life and human health. Anchialine pool ecosystems and the endemic species they support are at risk and provide an opportunity to sample for presence of contaminants prior to diffusion in the marine environment. In this study, we tested the potential use of nitrogen isotopes in the tissues of a dominant anchialine pool grazing shrimp (Halocaridina rubra), as a bioindicator for sewage in groundwater flowing through their habitats. Water quality parameters and shrimp tissue isotopes (N and C) were collected from pools exposed to a range of sewage contamination along the West Hawai'i coastal corridor from 2015 to 2017. Data were used to test for spatial and temporal variability both within and among pools and to examine the relationship between stable isotopes and water quality parameters. Within 22 pools, mean δ15N from whole tissue samples ranged between 2.74‰ and 22.46‰. Variability of isotope values was low within individual pools and within pool clusters. However, δ15N differed significantly between areas and indicated that sewage is entering groundwater in some of the sampled locations. The significant positive relationship between δ15N and dissolved nitrogen (p<0.001, R2 = 0.84) and δ15N and phosphorus (p<0.001, R2 = 0.9) support this conclusion. In a mesocosm experiment, the nitrogen half-life for H. rubra tissue was estimated to be 20.4 days, demonstrating that the grazer provides a time-integrative sample compared to grab-sample measurements of dissolved nutrients. Ubiquitous grazers such as H. rubra may prove a useful and cost-effective method for δ15N detection of sewage in conjunction with standard monitoring methods, enabling sampling of a large number of pools to establish and refine monitoring programs, especially because anchialine habitats typically support no macroalgae.
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Affiliation(s)
- Lisa C. Marrack
- Department of Tropical Conservation Biology and Environmental Science, University of Hawaii, Hilo, Hawaiʻi, United States of America
| | - Sallie C. Beavers
- Kaloko-Honokōhau National Historical Park, Kailua-Kona, Hawaiʻi, United States of America
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8
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Ziegler AF, Bluhm BA, Renaud PE, Jørgensen LL. Isotopic turnover in polar cod (Boreogadus saida) muscle determined through a controlled feeding experiment. JOURNAL OF FISH BIOLOGY 2023; 102:1442-1454. [PMID: 36999199 DOI: 10.1111/jfb.15389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 03/29/2023] [Indexed: 06/09/2023]
Abstract
Polar cod (Boreogadus saida) is an important trophic link within Arctic marine food webs and is likely to experience diet shifts in response to climate change. One important tool for assessing organism diet is bulk stable isotope analysis. However, key parameters necessary for interpreting the temporal context of stable isotope values are lacking, especially for Arctic species. This study provides the first experimental determination of isotopic turnover (as half-life) and trophic discrimination factors (TDFs) of both δ13 C and δ15 N in adult polar cod muscle. Using a diet enriched in both 13 C and 15 N, we measured isotopic turnover times of 61 and 49 days for δ13 C and δ15 N, respectively, with metabolism accounting for >94% of the total turnover. These half-life estimates are valid for adult polar cod (>3 years) experiencing little somatic growth. We measured TDFs in our control of 2.6‰ and 3.9‰ for δ13 C and δ15 N, respectively, and we conclude that applying the commonly used TDF of ~1‰ for δ13 C for adult polar cod may lead to misrepresentation of dietary carbon source, while the use of 3.8‰ for δ15 N is appropriate. Based on these results, we recommend that studies investigating seasonal shifts in the diet of adult polar cod sample at temporal intervals of at least 60 days to account for isotopic turnover in polar cod muscle. Although isotopic equilibrium was reached by the fish in this study, it was at substantially lower isotope values than the diet. Additionally, the use of highly enriched algae in the experimental feed caused very high variability in diet isotope values which precluded accurate calculation of TDFs from the enriched fish. As a result of the challenges faced in this study, we discourage the use of highly enriched diets for similar experiments and provide recommendations to guide the design of future isotopic turnover experiments.
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Affiliation(s)
- Amanda Fern Ziegler
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway
- Institute of Marine Research, Fram Centre, Tromsø, Norway
| | - Bodil A Bluhm
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway
| | - Paul E Renaud
- Akvaplan-niva, Fram Centre for Climate and the Environment, Tromsø, Norway
- University Centre in Svalbard, Longyearbyen, Norway
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9
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Navarro-Castilla Á, Hernández MC, Barja I. An Experimental Study in Wild Wood Mice Testing Elemental and Isotope Analysis in Faeces to Determine Variations in Food Intake Amount. Animals (Basel) 2023; 13:ani13071176. [PMID: 37048432 PMCID: PMC10093285 DOI: 10.3390/ani13071176] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/16/2023] [Accepted: 03/24/2023] [Indexed: 03/30/2023] Open
Abstract
The analysis of carbon and nitrogen elemental (C, N) and isotopic compositions (δ13C, δ15N) in faeces are considered reliable methodologies for the study of diet in wildlife. Here, we tested the suitability of these techniques to detect variations in the amount of food intake. We captured wild wood mice (Apodemus sylvaticus) with Sherman live traps where bait access was initially free, and later it was experimentally limited inside by four different devices to cause intended variations in the amount ingested. The total C and N (%) and stable δ13C and δ15N isotopic values were determined for the bait and in mice faecal samples. Faecal values were lower than bait ones except for N, likely due to animal matter ingested before capture. No significant differences in total C, N and δ13C were found due to individual traits. However, breeding males showed higher δ15N values than breeding females, probably due to differences in energy and protein demands between both sexes during the breeding season. Only δ13C detected food intake variations (≥2 g). Despite further research being needed, these results initially support the potential of δ13C to provide information on the amount ingested, thus being useful to complement trophic ecology studies.
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Affiliation(s)
- Álvaro Navarro-Castilla
- Eco- and Ethophysiology Lab, Departamento de Biología, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, C. Darwin 2, 28049 Madrid, Spain
- Correspondence:
| | - M. Carmen Hernández
- Eco- and Ethophysiology Lab, Departamento de Biología, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Isabel Barja
- Eco- and Ethophysiology Lab, Departamento de Biología, Universidad Autónoma de Madrid, 28049 Madrid, Spain
- Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, C. Darwin 2, 28049 Madrid, Spain
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10
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Inferences to estimate consumer’s diet using stable isotopes: Insights from a dynamic mixing model. PLoS One 2022; 17:e0263454. [PMID: 35130334 PMCID: PMC8820609 DOI: 10.1371/journal.pone.0263454] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 01/19/2022] [Indexed: 12/04/2022] Open
Abstract
Stable isotope ratios are used to reconstruct animal diet in trophic ecology via mixing models. Several assumptions of stable isotope mixing models are critical, i.e., constant trophic discrimination factor and isotopic equilibrium between the consumer and its diet. The isotopic turnover rate (λ and its counterpart the half-life) affects the dynamics of isotopic incorporation for an organism and the isotopic equilibrium assumption: λ involves a time lag between the real assimilated diet and the diet estimated by mixing models at the individual scale. Current stable isotope mixing model studies consider neither this time lag nor even the dynamics of isotopic ratios in general. We developed a mechanistic framework using a dynamic mixing model (DMM) to assess the contribution of λ to the dynamics of isotopic incorporation and to estimate the bias induced by neglecting the time lag in diet reconstruction in conventional static mixing models (SMMs). The DMM includes isotope dynamics of sources (denoted δs), λ and frequency of diet-switch (ω). The results showed a significant bias generated by the SMM compared to the DMM (up to 50% of differences). This bias can be strongly reduced in SMMs by averaging the isotopic variations of the food sources over a time window equal to twice the isotopic half-life. However, the bias will persist (∼15%) for intermediate values of the ω/λ ratio. The inferences generated using a case study highlighted that DMM enhanced estimates of consumer’s diet, and this could avoid misinterpretation in ecosystem functioning, food-web structure analysis and underlying biological processes.
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Lobry J, Mounier F, Ballutaud M, Chevillot X, Gascuel D, Budzinski H, Labadie P, Drouineau H. ESCROpath, a Bayesian mixing model to quantify diets and trophic flows in aquatic food webs. Methods Ecol Evol 2022. [DOI: 10.1111/2041-210x.13808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Florence Mounier
- INRAE UR EABX F‐33612 Cestas cedex France
- DataReportR 33610 Canéjan France
| | - Marine Ballutaud
- Université de Lille CNRS Université Littoral Côte d'Opale UMR 8187 LOG station marine de Wimereux F‐59000 France
| | | | - Didier Gascuel
- ESE Ecology and ecosystem health Institut Agro INRAE 35042 Rennes France
| | | | - Pierre Labadie
- Université de Bordeaux UMR CNRS 5805 EPOC 33405 Talence France
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12
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Cutting KA, Rotella JJ, Grusing E, Waxe JA, Nunlist E, Sowell BF. Nutrient sources for offspring formation: diet-mother and mother-offspring isotope discrimination in domesticated gallinaceous birds. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2021; 57:553-562. [PMID: 34632885 DOI: 10.1080/10256016.2021.1984905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 08/26/2021] [Indexed: 06/13/2023]
Abstract
Stable isotope techniques can be used to assess nutrient acquisition and allocation strategies used to produce offspring. Before stable isotope techniques can be employed, researchers need reliable isotope discrimination values. In this context, isotope discrimination compares the difference in the isotope ratio between the maternal-offspring tissue that occurs during nutrient transfer prior to egg laying. Currently, isotope discrimination values are unknown between the maternal blood constituents - that reflect different temporal scales of integration - and downy feathers of their offspring. In this study, we experimentally derive isotope discrimination relationships between maternal diet-blood constituents for egg laying, and between maternal blood constituents-down feathers of offspring in an experiment with 3 types of domesticated gallinaceous birds raised on known diets. Our experiment is the first to report isotope discrimination values for maternal blood constituents-down of offspring in avian taxa and provides a new sampling technique that is less invasive than previously available as collecting down does not require sampling viable eggs or individuals. Future researchers can use these results to assist in identifying nutrient sources used by adult birds to produce young.
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Affiliation(s)
- Kyle A Cutting
- Red Rock Lakes National Wildlife Refuge, U.S. Fish and Wildlife Service, Lima, MT, USA
- Department of Ecology, Montana State University, Bozeman, MT, USA
| | - Jay J Rotella
- Department of Ecology, Montana State University, Bozeman, MT, USA
| | - Emma Grusing
- Red Rock Lakes National Wildlife Refuge, U.S. Fish and Wildlife Service, Lima, MT, USA
| | - James A Waxe
- The Centennial Sandhills Preserve, The Nature Conservancy, Lima, MT, USA
| | - Erika Nunlist
- Department of Animal and Range Sciences, Montana State University, Bozeman, MT, USA
| | - Bok F Sowell
- Department of Animal and Range Sciences, Montana State University, Bozeman, MT, USA
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Lerner JE, Forster I, Hunt BPV. Experimentally derived trophic enrichment and discrimination factors for Chinook salmon, Oncorhynchus tshawytscha. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9092. [PMID: 33788330 DOI: 10.1002/rcm.9092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 03/08/2021] [Accepted: 03/27/2021] [Indexed: 06/12/2023]
Abstract
RATIONALE Stable isotope analysis (SIA) can provide important insights into food web structure and is a widely used tool in ecological conservation and management. It has recently been augmented by compound-specific stable isotope analysis of amino acids (CSIA-AA), an innovation that can provide greater precision when analyzing trophic level and food web connectivity. The utility of SIA rests on confidence in its constituent parameters such as the trophic enrichment factor (TEF). There is increasing emphasis on the need to experimentally derive species and tissue specific TEFs for studies utilizing SIA. Chinook salmon, Oncorhynchus tshawytscha, is a species with high potential for study using SIA due to the difficulty in observing its ecology during its marine phase and the significance of the conservation consequences of recent population declines. METHODS Bulk and amino acid-specific TEFs were determined for juvenile and adult Chinook salmon fed specific diets. Three controlled feeding studies were performed: adult salmon were fed a biofeed, juvenile salmon were fed a biofeed, and juvenile salmon were fed krill. Bulk and compound-specific stable isotope data were collected from diet samples and from salmon muscle tissue after a minimum of 8 weeks of controlled feeding. Bulk isotope signatures were measured using EA-IRMS and CSIA-AA signatures using GC/C-IRMS, allowing the TEFs to be calculated. RESULTS The bulk isotope TEFs were higher than those predicted for similar marine organisms and averaged 3.5‰ for ∆15 N and 1.3‰ for ∆13 C. The TEFs derived for nitrogen isotopes of amino acids were in line with expectations for this approach: the mean value for ∆15 NGlu - ∆15 NPhe was 7.06‰ and, using a multi-AA approach, the value for ∆15 NTrophic - ∆15 NSource was 6.67‰. For carbon isotopes of amino acids, the derived TEFs of Iso, Leu and Phe were near 0‰, as was that of Met, supporting their use of as source amino acids in future CSIA studies. CONCLUSIONS This study presents Chinook salmon-specific TEFs for bulk and amino acid SIA. It supports the application of future research applying SIA to the study of Chinook salmon and validates previous research on species-specific TEFs.
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Affiliation(s)
- Jacob E Lerner
- Institute for the Oceans and Fisheries, University of British Columbia, AERL, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020-2207 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Ian Forster
- Pacific Science Enterprise Centre, Fisheries and Oceans Canada, 4160 Marine Drive, West Vancouver, BC, V7V 1H2, Canada
| | - Brian P V Hunt
- Institute for the Oceans and Fisheries, University of British Columbia, AERL, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020-2207 Main Mall, Vancouver, BC, V6T 1Z4, Canada
- Hakai Institute, Tula Foundation, PO Box 309, Heriot Bay, BC, V0P 1H0, Canada
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14
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Pinzone M, Cransveld A, Tessier E, Bérail S, Schnitzler J, Das K, Amouroux D. Contamination levels and habitat use influence Hg accumulation and stable isotope ratios in the European seabass Dicentrarchus labrax. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 281:117008. [PMID: 33813195 DOI: 10.1016/j.envpol.2021.117008] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 03/15/2021] [Accepted: 03/20/2021] [Indexed: 06/12/2023]
Abstract
Hg accumulation in marine organisms depends strongly on in situ water or sediment biogeochemistry and levels of Hg pollution. To predict the rates of Hg exposure in human communities, it is important to understand Hg assimilation and processing within commercially harvested marine fish, like the European seabass Dicentrarchus labrax. Previously, values of Δ199Hg and δ202Hg in muscle tissue successfully discriminated between seven populations of European seabass. In the present study, a multi-tissue approach was developed to assess the underlying processes behind such discrimination. We determined total Hg content (THg), the proportion of monomethyl-Hg (%MeHg), and Hg isotopic composition (e.g. Δ199Hg and δ202Hg) in seabass liver. We compared this to the previously published data on muscle tissue and local anthropogenic Hg inputs. The first important finding of this study showed an increase of both %MeHg and δ202Hg values in muscle compared to liver in all populations, suggesting the occurrence of internal MeHg demethylation in seabass. This is the first evidence of such a process occurring in this species. Values for mass-dependent (MDF, δ202Hg) and mass-independent (MIF, Δ199Hg) isotopic fractionation in liver and muscle accorded with data observed in estuarine fish (MDF, 0-1‰ and MIF, 0-0.7‰). Black Sea seabass stood out from other regions, presenting higher MIF values (≈1.5‰) in muscle and very low MDF (≈-1‰) in liver. This second finding suggests that under low Hg bioaccumulation, Hg isotopic composition may allow the detection of a shift in the habitat use of juvenile fish, such as for first-year Black Sea seabass. Our study supports the multi-tissue approach as a valid tool for refining the analysis of Hg sourcing and metabolism in a marine fish. The study's major outcome indicates that Hg levels of pollution and fish foraging location are the main factors influencing Hg species accumulation and isotopic fractionation in the organisms.
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Affiliation(s)
- Marianna Pinzone
- Freshwater and Oceanic Sciences Unit of Research (FOCUS), Laboratory of Oceanology, University of Liège, B6c Allée du 6 Août, 4000, Liège, Belgium
| | - Alice Cransveld
- Freshwater and Oceanic Sciences Unit of Research (FOCUS), Laboratory of Oceanology, University of Liège, B6c Allée du 6 Août, 4000, Liège, Belgium
| | - Emmanuel Tessier
- Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les Matériaux (IPREM), Technopôle Helioparc, 2 Avenue Pierre Angot, 64053, Pau Cedex 09, France
| | - Sylvain Bérail
- Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les Matériaux (IPREM), Technopôle Helioparc, 2 Avenue Pierre Angot, 64053, Pau Cedex 09, France
| | - Joseph Schnitzler
- Freshwater and Oceanic Sciences Unit of Research (FOCUS), Laboratory of Oceanology, University of Liège, B6c Allée du 6 Août, 4000, Liège, Belgium; Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine of Hannover, Foundation, Werftstraße 6, 25761, Büsum, Schleswig-Holstein, Germany
| | - Krishna Das
- Freshwater and Oceanic Sciences Unit of Research (FOCUS), Laboratory of Oceanology, University of Liège, B6c Allée du 6 Août, 4000, Liège, Belgium.
| | - David Amouroux
- Universite de Pau et des Pays de l'Adour, E2S UPPA, CNRS, Institut des Sciences Analytiques et de Physico-chimie pour l'Environnement et les Matériaux (IPREM), Technopôle Helioparc, 2 Avenue Pierre Angot, 64053, Pau Cedex 09, France
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15
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Breault DN, Johnson CJ, Todd M, Verenitch SS, Gillingham MP. Spatial and temporal variability in the diet of Pacific marten ( Martes caurina) on Haida Gwaii: an apex predator in a highly modified ecosystem. CAN J ZOOL 2021. [DOI: 10.1139/cjz-2020-0076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Knowledge of the diet ecology of apex predators in insular island ecosystems has direct applications to the conservation of endemic species at risk of extinction. We used stable isotopes of carbon and nitrogen to infer resource-use strategies of an indigenous predator, the Pacific marten (Martes caurina (Merriam, 1890)), in a highly modified ecosystem on Haida Gwaii, British Columbia, Canada. We used Bayesian isotopic mixing models to estimate the relative contributions of different food sources to marten diet across seasons and during overall lifetime, and to determine how diet varied with different levels of access to marine resources. Isotopes of carbon and nitrogen measured in hair and muscle tissue suggested that marten consumed salmon (3%–17%) and berries (25%–37%) seasonally; these diet groups were relatively minor components of the lifetime diet. Analysis of bone collagen suggested that terrestrial fauna — including birds, deer, small mammals, and invertebrates — contributed the most to diet (41%–55%), and marine invertebrates (38%–48%), not salmon (0%–3%), were the main allochthonous marine nutrient subsidy to lifetime diet. Plasticity in foraging ecology, combined with a broad dietary niche, introduced prey, notably the invasive Sitka black-tailed deer (Odocoileus hemionus sitkensis Merriam, 1898), as well as abundant marine resources, may allow marten to outcompete other indigenous and endemic carnivores on Haida Gwaii.
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Affiliation(s)
- David N. Breault
- University of Northern British Columbia, Ecosystem Science and Management, 3333 University Way, Prince George, BC V2N 4Z9, Canada
| | - Chris J. Johnson
- University of Northern British Columbia, Ecosystem Science and Management, 3333 University Way, Prince George, BC V2N 4Z9, Canada
| | - Melissa Todd
- Coast Forest Region Research Section, BC Ministry of Forests, Lands, Natural Resource Operations, and Rural Development, Suite #103 – 2100 Labieux Road, Nanaimo, BC V9T 6E9, Canada
| | - Sergei S. Verenitch
- Aquatech Enviroscience Laboratories, Inc., 825 Clayton Road, North Saanich, BC V8L 5M3, Canada
| | - Michael P. Gillingham
- University of Northern British Columbia, Ecosystem Science and Management, 3333 University Way, Prince George, BC V2N 4Z9, Canada
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16
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Ordóñez-Grande B, Fernández-Alacid L, Sanahuja I, Sánchez-Nuño S, Fernández-Borràs J, Blasco J, Ibarz A. Evaluating mucus exudation dynamics through isotopic enrichment and turnover of skin mucus fractions in a marine fish model. CONSERVATION PHYSIOLOGY 2020; 8:coaa095. [PMID: 33442471 PMCID: PMC7787050 DOI: 10.1093/conphys/coaa095] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 08/12/2020] [Accepted: 11/12/2020] [Indexed: 06/12/2023]
Abstract
Fish skin mucus is composed of insoluble components, which form the physical barrier, and soluble components, which are key for interrelationship functions. Mucus is continuously secreted, but rates of production and exudation are still unknown, as are the underlying mechanisms. Using stable isotope analysis, here, we evaluate skin mucus turnover and renewal in gilthead sea bream, separating raw mucus and its soluble and insoluble fractions. Isotopic abundance analysis reveals no differences between mucus and white muscle, thus confirming mucus samples as reliable non-invasive biomarkers. Mucus production was evaluated using a single labelled meal packaged in a gelatine capsule, with both 13C and 15N, via a time-course trial. 13C was gradually allocated to skin mucus fractions over the first 12 h and was significantly (4-fold) higher in the soluble fraction, indicating a higher turnover of soluble mucus components that are continuously produced and supplied. 15N was also gradually allocated to mucus, indicating incorporation of new proteins containing the labelled dietary amino acids, but with no differences between fractions. When existent mucus was removed, dietary stable isotopes revealed stimulated mucus neoformation dependent on the components. All this is novel knowledge concerning skin mucus dynamics and turnover in fish and could offer interesting non-invasive approaches to the use of skin mucus production in ecological or applied biological studies such as climate change effects, human impact, alterations in trophic networks or habitat degradation, especially of wild-captured species or protected species.
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Affiliation(s)
| | - Laura Fernández-Alacid
- Corresponding author: Department of Cell Biology, Physiology and Immunology, University of Barcelona, Barcelona, Spain.
| | - Ignasi Sanahuja
- Department of Cell Biology, Physiology and Immunology, University of Barcelona, Barcelona, Spain
| | - Sergio Sánchez-Nuño
- Department of Cell Biology, Physiology and Immunology, University of Barcelona, Barcelona, Spain
| | - Jaume Fernández-Borràs
- Department of Cell Biology, Physiology and Immunology, University of Barcelona, Barcelona, Spain
| | - Josefina Blasco
- Department of Cell Biology, Physiology and Immunology, University of Barcelona, Barcelona, Spain
| | - Antoni Ibarz
- Department of Cell Biology, Physiology and Immunology, University of Barcelona, Barcelona, Spain
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17
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Johnson DL, Henderson MT, Anderson DL, Booms TL, Williams CT. Bayesian stable isotope mixing models effectively characterize the diet of an Arctic raptor. J Anim Ecol 2020; 89:2972-2985. [PMID: 33020919 DOI: 10.1111/1365-2656.13361] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/01/2020] [Indexed: 12/01/2022]
Abstract
Bayesian stable isotope mixing models (BSIMMs) for δ13 C and δ15 N can be a useful tool to reconstruct diets, characterize trophic relationships, and assess spatiotemporal variation in food webs. However, use of this approach typically requires a priori knowledge on the level of enrichment occurring between the diet and tissue of the consumer being sampled (i.e. a trophic discrimination factor or TDF). Trophic discrimination factors derived from captive feeding studies are highly variable, and it is challenging to select the appropriate TDF for diet estimation in wild populations. We introduce a novel method for estimating TDFs in a wild population-a proportionally balanced equation that uses high-precision diet estimates from nest cameras installed on a subset of nests in lieu of a controlled feeding study (TDFCAM ). We tested the ability of BSIMMs to characterize diet in a free-living population of gyrfalcon Falco rusticolus nestlings by comparing model output to high-precision nest camera diet estimates. We analysed the performance of models formulated with a TDFCAM against other relevant TDFs and assessed model sensitivity to an informative prior. We applied the most parsimonious model inputs to a larger sample to analyse broad-scale temporal dietary trends. Bayesian stable isotope mixing models fitted with a TDFCAM and uninformative prior had the best agreement with nest camera data, outperforming TDFs derived from captive feeding studies. BSIMMs produced with a TDFCAM produced reliable diet estimates at the nest level and accurately identified significant temporal shifts in gyrfalcon diet within and between years. Our method of TDF estimation produced more accurate estimates of TDFs in a wild population than traditional approaches, consequently improving BSIMM diet estimates. We demonstrate how BSIMMs can complement a high-precision diet study by expanding its spatiotemporal scope of inference and recommend this integrative methodology as a powerful tool for future trophic studies.
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Affiliation(s)
- Devin L Johnson
- Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK, USA
| | | | | | | | - Cory T Williams
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
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18
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Exploring source differences on diet-tissue discrimination factors in the analysis of stable isotope mixing models. Sci Rep 2020; 10:15816. [PMID: 32978550 PMCID: PMC7519091 DOI: 10.1038/s41598-020-73019-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 09/10/2020] [Indexed: 11/08/2022] Open
Abstract
Stable isotope mixing models are regularly used to provide probabilistic estimates of source contributions to dietary mixtures. Whilst Bayesian implementations of isotope mixing models have become prominent, the use of appropriate diet-tissue discrimination factors (DTDFs) remains as the least resolved aspect. The DTDFs are critical in providing accurate inferences from these models. Using both simulated and laboratory-based experimental data, this study provides conceptual and practical applications of isotope mixing models by exploring the role of DTDFs. The experimental study used Mozambique Tilapia Oreochromis mossambicus, a freshwater fish, to explore multi-tissue variations in isotopic incorporation patterns, and to evaluate isotope mixing model outputs based on the experiment- and literature-based DTDFs. Isotope incorporation patterns were variable for both muscle and fin tissues among the consumer groups that fed diet sources with different stable isotope values. Application of literature-based DTDFs in isotope mixing models consistently underestimated the dietary proportions of all single-source consumer groups. In contrast, application of diet-specific DTDFs provided better dietary estimates for single-source consumer groups. Variations in the proportional contributions of the individual sources were, nevertheless, observed for the mixed-source consumer group, which suggests that isotope assimilation of the individual food sources may have been influenced by other underlying physiological processes. This study provides evidence that stable isotope values from different diet sources exhibit large variations as they become incorporated into consumer tissues. This suggests that the application of isotope mixing models requires consideration of several aspects such as diet type and the associated biological processes that may influence DTDFs.
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19
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Twining CW, Taipale SJ, Ruess L, Bec A, Martin-Creuzburg D, Kainz MJ. Stable isotopes of fatty acids: current and future perspectives for advancing trophic ecology. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190641. [PMID: 32536315 PMCID: PMC7333957 DOI: 10.1098/rstb.2019.0641] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/26/2020] [Indexed: 12/16/2022] Open
Abstract
To understand consumer dietary requirements and resource use across ecosystems, researchers have employed a variety of methods, including bulk stable isotope and fatty acid composition analyses. Compound-specific stable isotope analysis (CSIA) of fatty acids combines both of these tools into an even more powerful method with the capacity to broaden our understanding of food web ecology and nutritional dynamics. Here, we provide an overview of the potential that CSIA studies hold and their constraints. We first review the use of fatty acid CSIA in ecology at the natural abundance level as well as enriched physiological tracers, and highlight the unique insights that CSIA of fatty acids can provide. Next, we evaluate methodological best practices when generating and interpreting CSIA data. We then introduce three cutting-edge methods: hydrogen CSIA of fatty acids, and fatty acid isotopomer and isotopologue analyses, which are not yet widely used in ecological studies, but hold the potential to address some of the limitations of current techniques. Finally, we address future priorities in the field of CSIA including: generating more data across a wider range of taxa; lowering costs and increasing laboratory availability; working across disciplinary and methodological boundaries; and combining approaches to answer macroevolutionary questions. This article is part of the theme issue 'The next horizons for lipids as 'trophic biomarkers': evidence and significance of consumer modification of dietary fatty acids'.
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Affiliation(s)
- Cornelia W. Twining
- Limnological Institute, University of Konstanz, 78464 Konstanz, Germany
- Max Planck Institute for Animal Behavior, 78315 Radolfzell, Germany
| | - Sami J. Taipale
- Department of Biological and Environmental Science, University of Jyväskylä, 40014 Jyväskylä, Finland
| | - Liliane Ruess
- Institute of Biology, Ecology Group, Humboldt Universität zu Berlin, 10115 Berlin, Germany
| | - Alexandre Bec
- University Clermont Auvergne, 63178 Clermont-Ferrand, France
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20
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Studying animal niches using bulk stable isotope ratios: an updated synthesis. Oecologia 2020; 193:27-51. [DOI: 10.1007/s00442-020-04654-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 04/11/2020] [Indexed: 10/24/2022]
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21
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Varela JL, Carrera I, Medina A. Seasonal feeding patterns of Atlantic bluefin tuna (Thunnus thynnus) in the Strait of Gibraltar. MARINE ENVIRONMENTAL RESEARCH 2020; 153:104811. [PMID: 31606142 DOI: 10.1016/j.marenvres.2019.104811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/25/2019] [Accepted: 10/04/2019] [Indexed: 06/10/2023]
Abstract
The Strait of Gibraltar (SoG) houses a large diversity of marine species including large pelagic animals that use this area as permanent or temporary habitat. In particular, the SoG is home to a population of adult and sub-adult Atlantic bluefin tuna (Thunnus thynnus) that occurs there for most of the year. To gain further insight into the life history of this ABFT population, seasonal feeding patterns were investigated combining stomach content analysis (SCA) and stable isotopes analysis (SIA) of muscle and liver tissues. Our results reveal seasonal variations in feeding patterns, which are evidenced by a significant shift in the diet composition and the highest food consumption rates that take place in spring, prior to the spawning season. These changes in feeding habits are consistent with the varying energetic needs along the species' annual biological cycle. The present observations confirm the SoG as an important foraging ground for ABFT resident populations and may have further implications for the management of the resource.
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Affiliation(s)
- José Luis Varela
- Departamento de Biología. Facultad de Ciencias del Mar y Ambientales, Campus de Excelencia Internacional del Mar (CEI·MAR), 11510 Puerto Real, Cádiz, Spain.
| | - Irene Carrera
- Departamento de Biología. Facultad de Ciencias del Mar y Ambientales, Campus de Excelencia Internacional del Mar (CEI·MAR), 11510 Puerto Real, Cádiz, Spain
| | - Antonio Medina
- Departamento de Biología. Facultad de Ciencias del Mar y Ambientales, Campus de Excelencia Internacional del Mar (CEI·MAR), 11510 Puerto Real, Cádiz, Spain
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22
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Skinner C, Mill AC, Newman SP, Newton J, Cobain MRD, Polunin NVC. Novel tri-isotope ellipsoid approach reveals dietary variation in sympatric predators. Ecol Evol 2019; 9:13267-13277. [PMID: 31893024 PMCID: PMC6936247 DOI: 10.1002/ece3.5779] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/01/2019] [Accepted: 10/04/2019] [Indexed: 11/21/2022] Open
Abstract
Sympatric species may partition resources to reduce competition and facilitate co-existence. While spatial variation and specialization in feeding strategies may be prevalent among large marine predators, studies have focussed on sharks, birds, and marine mammals. We consider for the first time the isotopic niche partitioning of co-occurring, teleost reef predators spanning multiple families. Using a novel tri-isotope ellipsoid approach, we investigate the feeding strategies of seven of these species across an atoll seascape in the Maldives. We demonstrate substantial spatial variation in resource use of all predator populations. Furthermore, within each area, there was evidence of intraspecific variation in feeding behaviors that could not wholly be attributed to individual body size. Assessing species at the population level will mask these intraspecific differences in resource use. Knowledge of resource use is important for predicting how species will respond to environmental change and spatial variation should be considered when investigating trophic diversity.
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Affiliation(s)
- Christina Skinner
- School of Natural and Environmental SciencesNewcastle UniversityNewcastleUK
| | - Aileen C. Mill
- School of Natural and Environmental SciencesNewcastle UniversityNewcastleUK
| | - Steven P. Newman
- School of Natural and Environmental SciencesNewcastle UniversityNewcastleUK
- Banyan Tree Marine LabVabbinfaruRepublic of the Maldives
| | - Jason Newton
- NERC Life Sciences Mass Spectrometry FacilityScottish Universities Environmental Research CentreEast KilbrideUK
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