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Gas chromatography with electron capture negative ion mass spectrometry (GC/ECNI-MS) was used to quantify and compare halogenated natural products (HNPs) and selected anthropogenic persistent organic pollutants (POPs) in individual samples of 17 fish species from the Seychelles (Western Indian Ocean). The sum-HNP amounts (9.5-1100 ng/g lipid mass (lm)) were between 1 and 2 orders of magnitude higher than those of the sum of seven abundant polychlorinated biphenyl (PCB) congeners (0.2-15 ng/g lm) and dichlorodiphenyltrichloroethane-related compounds (DDTs) (<1.1-43 ng/g lm). Within the group of HNPs, the two tetrabrominated phenoxyanisoles (aka methoxylated diphenyl ethers, MeO-BDEs), 2'-MeO-BDE 68 â« 6-MeO-BDE 47, were predominant in most cases. Pearson correlation analysis showed that MeO-BDE levels were positively correlated with less abundant HNPs (2,2'-diMeO-BB 80, 2',6-diMeO-BDE 68, and Br6-DBP) (p < 0.01). Accordingly, HNPs, rather than PCBs and DDTs, were the predominant polyhalogenated contaminants in the current species.
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Produtos Biológicos , Peixes , Bifenilos Policlorados , Poluentes Químicos da Água , Animais , Peixes/metabolismo , Poluentes Químicos da Água/metabolismo , Poluentes Químicos da Água/química , Poluentes Químicos da Água/análise , Produtos Biológicos/metabolismo , Produtos Biológicos/química , Bifenilos Policlorados/metabolismo , Bifenilos Policlorados/análise , Bifenilos Policlorados/química , Oceano Índico , Seicheles , Bioacumulação , Cromatografia Gasosa-Espectrometria de Massas , Recifes de CoraisRESUMO
An important provision of the Minamata Convention on Mercury is to monitor and evaluate the effectiveness of the adopted measures and its implementation. Here, we describe for the first time currently available biotic mercury (Hg) data on a global scale to improve the understanding of global efforts to reduce the impact of Hg pollution on people and the environment. Data from the peer-reviewed literature were compiled in the Global Biotic Mercury Synthesis (GBMS) database (>550,000 data points). These data provide a foundation for establishing a biomonitoring framework needed to track Hg concentrations in biota globally. We describe Hg exposure in the taxa identified by the Minamata Convention: fish, sea turtles, birds, and marine mammals. Based on the GBMS database, Hg concentrations are presented at relevant geographic scales for continents and oceanic basins. We identify some effective regional templates for monitoring methylmercury (MeHg) availability in the environment, but overall illustrate that there is a general lack of regional biomonitoring initiatives around the world, especially in Africa, Australia, Indo-Pacific, Middle East, and South Atlantic and Pacific Oceans. Temporal trend data for Hg in biota are generally limited. Ecologically sensitive sites (where biota have above average MeHg tissue concentrations) have been identified throughout the world. Efforts to model and quantify ecosystem sensitivity locally, regionally, and globally could help establish effective and efficient biomonitoring programs. We present a framework for a global Hg biomonitoring network that includes a three-step continental and oceanic approach to integrate existing biomonitoring efforts and prioritize filling regional data gaps linked with key Hg sources. We describe a standardized approach that builds on an evidence-based evaluation to assess the Minamata Convention's progress to reduce the impact of global Hg pollution on people and the environment.
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Monitoramento Biológico , Monitoramento Ambiental , Mercúrio , Mercúrio/análise , Monitoramento Biológico/métodos , Animais , Monitoramento Ambiental/métodos , Biota , Poluentes Químicos da Água/análise , Aves , Compostos de Metilmercúrio/análise , Peixes/metabolismoRESUMO
Akanda National Park (ANP) is composed of mangrove ecosystems bordering Libreville, Gabon's capital. The contamination of aquatic resources from the ANP by persistent organic pollutants (POPs) and trace metals (TMs) was never evaluated. To provide a basis for their monitoring in the ANP, five species (two fish, two mollusks, and one crustacean) were analyzed from three sampling sites in 2017. Contamination levels for POPs and TMs were below maximum acceptable limits for seafood, including Cd and Pb. No DDT was found in any sample. Inter-specific differences were more obvious than the differences among sites, although the results may be biased by an unbalanced sampling design. The oyster Crassostrea gasar was the most contaminated species, making this species a good candidate to assess environmental contamination in the area. The studied species also contained essential elements, such as Fe, Zn and Mn at interesting levels in a nutritional point of view.
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Crassostrea , Metais Pesados , Oligoelementos , Poluentes Químicos da Água , Animais , Organismos Aquáticos , Poluentes Orgânicos Persistentes , Ecossistema , Gabão , Parques Recreativos , Monitoramento Ambiental/métodos , Poluentes Químicos da Água/análise , Oligoelementos/análise , Metais Pesados/análiseRESUMO
Some health agencies have issued precautionary principle fish advisories to pregnant women based on the presence of methylmercury (MeHg) in fish that could possibly be harmful to the developing fetus. Fish, however, is a rich source of selenium (Se) and other nutrients essential for normal brain development. Selenium is also thought to have a key role in alleviating MeHg toxicity. We estimated the dietary Se and MeHg intakes and dietary Se:Hg molar ratios from the fish consumed in a high fish-eating pregnant cohort where no adverse associations of fish consumption and outcomes has been reported. We used dietary data collected as part of the Seychelles Child Development Study Nutrition Cohort 2 (n = 1419). In this cohort 98% of participants consumed fish, with an average intake of 106.2 g per day. Daily Se intakes from fish consumption were 61.6 µg/ d, within the range recommended during pregnancy. The mean dietary Se:Hg molar ratios was 6. These findings demonstrate that fish consumption exposes pregnant Seychellois women to Se in excess of MeHg. Based on these findings, fish consumption, especially fish with Se:Hg ratios above 1, may help pregnant women achieve optimum dietary Se intakes, which may protect against MeHg toxicity.
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Mercúrio , Compostos de Metilmercúrio , Selênio , Criança , Animais , Feminino , Humanos , Gravidez , Mercúrio/análise , Selênio/análise , Seicheles , Desenvolvimento Infantil , PeixesRESUMO
The Republic of Seychelles is located in Western-Central Indian Ocean, and marine capture fisheries play a key role in the country's economic and social life in terms of food security, employment, and cultural identity. The Seychellois are among the highest per capita fish-consuming people in the world, with a high reliance on fish for protein. However, the diet is in transition, moving towards a Western-style diet lower in fish and higher in animal meat and easily available, highly processed foods. The aim of this study was to examine and evaluate the protein content and quality of a wide range of marine species exploited by the Seychelles industrial and artisanal fisheries, as well as to further to assess the contribution of these species to the daily intake recommended by the World Health Organization (WHO). A total of 230 individuals from 33 marine species, including 3 crustaceans, 1 shark, and 29 teleost fish, were collected from the Seychelles waters during 2014-2016. All analyzed species had a high content of high-quality protein, with all indispensable amino acids above the reference value pattern for adults and children. As seafood comprises almost 50% of the consumed animal protein in the Seychelles, it is of particular importance as a source of essential amino acids and associated nutrients, and as such every effort to sustain the consumption of regional seafood should be encouraged.
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Trace elements and δ15N values were analysed in micronekton (crustaceans, fishes and squids) sampled in the south-western Indian Ocean. Myctophids were associated with high concentrations of arsenic at La Pérouse and MAD-Ridge seamounts, and with lead and manganese at MAD-Ridge and in the Mozambique Channel. The difference in cadmium, copper and zinc concentrations between micronekton broad categories reflected differing metabolic and storage processes. When significant, negative relationships were found between micronekton body size and trace element concentrations, which can possibly be attributed to differing metabolic activity in young and old individuals, dietary shifts and/or dilution effect of growth. No relationships were found between trace element concentrations and δ15N values of micronekton (except cobalt which decreased with increasing δ15N values), since most trace elements are not biomagnified in food webs due to regulation and excretion processes within organisms. All trace element pairs were positively correlated in fishes suggesting regulation processes.
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Arsênio , Oligoelementos , Animais , Oligoelementos/análise , Cobre/análise , Cádmio/análise , Manganês/análise , Arsênio/análise , Oceano Índico , Peixes/metabolismo , Zinco/análise , Cobalto/análiseRESUMO
The concentrations of 13 trace elements were determined in 1032 muscles of 54 small-scale fisheries species collected from the Seychelles waters between 2013 and 2019. Overall, profiles were dominated by zinc (Zn) > arsenic (As) > iron (Fe) > copper (Cu) > selenium (Se), with the spiny lobsters, spanner crab and octopus exhibiting the highest levels of As, Cu and Zn while fish had higher Fe concentrations. Both taxonomy-dependent processes and ecological factors explained the interspecific differences of trace element profiles observed. A benefit-risk assessment revealed that crustaceans and cephalopods were good sources of Cu and Zn. One portion of any fish could provide 30-100 % of daily Se needs, and one portion of demersal and pelagic teleost fish could bring 5-20 % of Cu, Fe and Zn needs, especially for young adult and adult women. Finally, our analysis showed that there was very low health risks associated with small-scale fisheries consumption for the Seychelles population.
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Arsênio , Selênio , Oligoelementos , Animais , Arsênio/análise , Cobre/análise , Feminino , Pesqueiros , Peixes , Humanos , Alimentos Marinhos/análise , Selênio/análise , Seicheles , Oligoelementos/análise , Zinco/análiseRESUMO
Climate change is transforming coral reefs, threatening supply of essential dietary micronutrients from small-scale fisheries to tropical coastal communities. Yet the nutritional value of reef fisheries and climate impacts on micronutrient availability remain unclear, hindering efforts to sustain food and nutrition security. Here, we measure nutrient content in coral reef fishes in Seychelles and show that reef fish are important sources of selenium and zinc and contain levels of calcium, iron, and omega-3 fatty acids comparable with other animal-source foods. Using experimental fishing, we demonstrate that iron and zinc are enriched in fishes caught on regime-shifted macroalgal habitats, whereas selenium and omega-3 varied among species. We find substantial increases in nutrients available to fisheries over two decades following coral bleaching, particularly for iron and zinc after macroalgal regime shifts. Our findings indicate that, if managed sustainably, coral reef fisheries could remain important micronutrient sources along tropical coastlines despite escalating climate impacts.
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Mercury (Hg) concentrations and stable isotope values (δ13C and δ15N) were investigated in micronekton collected from La Pérouse and MAD-Ridge seamounts, Reunion Island and the southern Mozambique Channel. Organisms occupying epipelagic habitats showed lower Hg concentrations relative to deeper dwelling benthopelagic ones. Increasing Hg concentrations with increasing body size were recorded in the Mozambique Channel and Reunion Island. Positive relationships were observed between Hg levels and δ15N values in pelagic nekton assemblages collected at MAD-Ridge seamount and the southern Mozambique Channel, suggesting biomagnification of Hg. Concentrations of Hg in organisms across the south-western Indian Ocean were within the same range of values. Total Hg concentrations depend on a range of factors linked to habitat range, body size and trophic position of the individuals. To our knowledge, this is the first study investigating the patterns of Hg concentrations in pelagic nekton assemblages from the south-western Indian Ocean.
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Mercúrio , Poluentes Químicos da Água , Monitoramento Ambiental , Cadeia Alimentar , Humanos , Oceano Índico , Mercúrio/análise , Isótopos de Nitrogênio/análise , Poluentes Químicos da Água/análiseRESUMO
Background: Along with the development of the tropical tuna purse-seine fishery from the 1960s in the Atlantic Ocean and from the 1980s in the Indian Ocean, many projects and studies have been conducted to improve knowledge about the biology, migrations and dynamics of the stocks of target and non-target (i.e. bycatch) species taken in these fisheries. Since the 2000s, the European Union (EU) has been supporting Member States in the collection of biological data on species caught by their purse seine and pole and line fisheries, thus making it possible to have a long-term series of data. Biological data have never been saved by the different tuna commissions, unlike the catches by species and sizes by areas and periods. However, these data are essential to monitor the status of the fisheries and fuel the assessment models used by the tuna Regional Fisheries Management Organisations (tRFMOs) for the sustainable management and conservation of the fish stocks under their mandate. New information: We combined historical (1974-1999) and current (2003-2020) datasets on the biology of tropical tunas and bycatch fish caught by large-scale purse seiners in the Eastern Atlantic Ocean (EAO) and Western Indian Ocean (WIO). The resulting Tunabio database is presented in the present data paper and contains all available morphometric and biological data collected on more than 80,000 fish individuals.
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Tunas are among the most traded and valued fish species, and good traceability of tuna products in the world market is needed to protect both consumers and tuna stocks. To that purpose, high-resolution proton nuclear magnetic resonance (1H NMR) spectroscopy combined with multivariate data analysis was used to investigate the molecular components of the aqueous extract of white and red muscles in three species of wild tropical tuna species, namely yellowfin tuna (Thunnus albacares), skipjack tuna (Katsuwonus pelamis) and bigeye tuna (T. obesus). Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) applied to the processed 1H NMR spectra showed significant separation according to the species and size category (i.e., small tunas < 80 cm fork length vs large tunas > 80 cm fork length), the storage conditions on-board the purse-seine vessels (i.e., brine- vs deep-freezing), and the geographical origin (i.e., where the tuna was caught: Mozambique Channel vs western-central Indian Ocean). The major groups of metabolites responsible for differentiation in PLS-DA score plots were the dipeptides (anserine, carnosine) and organic acids (lactate, creatine/phosphocreatine) in the white muscle, and the free amino acids, essential nutrients (choline and its derivatives, phosphatidylethanolamine), dipeptides and organic acids in the red muscle. Our results showed that NMR-based metabolomics is a powerful tool to efficiently discriminate specific profiles among wild tuna species, raw muscle tissues, fish storage conditions and tuna geographical origin.
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Peixes , Atum , Animais , Oceano Índico , Espectroscopia de Ressonância Magnética , MetabolômicaRESUMO
Tropical tunas are largely consumed worldwide, providing major nutritional benefits to humans, but also representing the main exposure to methylmercury, a potent neurotoxin that biomagnifies along food webs. The combination of ecological tracers (nitrogen and carbon stable isotopes, δ15N and δ13C) to mercury concentrations in tunas is scarce yet crucial to better characterize the influence of tuna foraging ecology on mercury exposure and bioaccumulation. Given the difficulties to get modern and historical tuna samples, analyses have to be done on available and unique samples. However, δ13C values are often analysed on lipid-free samples to avoid bias related to lipid content. While lipid extraction with non-polar solvents is known to have no effect on δ15N values, its impact on mercury concentrations is still unclear. We used white muscle tissues of three tropical tuna species to evaluate the efficiency and repeatability of different lipid extraction protocols commonly used in δ13C and δ15N analysis. Dichloromethane was more efficient than cyclohexane in extracting lipids in tuna muscle, while the automated method appeared more efficient but as repeatable as the manual method. Lipid extraction with dichloromethane had no effect on mercury concentrations. This may result from i) the affinity of methylmercury to proteins in tuna flesh, ii) the low lipid content in tropical tuna muscle samples, and iii) the non-polar nature of dichloromethane. Our study suggests that lipid-free samples, usually prepared for tropical tuna foraging ecology research, can be used equivalently to bulk samples to document in parallel mercury concentrations at a global scale.
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Mercúrio , Compostos de Metilmercúrio , Animais , Humanos , Lipídeos , Músculos , AtumRESUMO
Concentrations, profiles and muscle-liver distribution of halogenated natural products (HNPs) and anthropogenic persistent organic pollutants (POPs) were investigated in five large pelagic fish species and one smaller planktivore fish species from the Western Indian Ocean. Analysis of swordfish muscle from the Seychelles revealed the predominance of HNPs, with the highest concentrations found for 2'-methoxy-2,3',4,5'- tetraBDE (2'-MeO-BDE 68 or BC-2), 6-methoxy-2,2',4,4'- tetraBDE (6-MeO-BDE 47 or BC-3) and 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1,2'-bipyrrole (Q1), along with varied contributions of further HNPs. The mean concentration of ∑HNPs (330 ng/g lw) was one or two orders of magnitude higher than ∑DDTs (60 ng/g lw) and ∑PCBs (6.8 ng/g lw). HNPs (BC-2, BC-3 and Q1) were also predominant in individual samples of three tropical tuna species from the Seychelles and from other regions of the Western Indian Ocean (Mozambique Channel, off Somalia and Chagos Archipelago). Non-targeted gas chromatography coupled with electron capture negative ion mass spectrometry operated in the selected ion monitoring mode (GC/ECNI-MS-SIM) analysis of one swordfish sample indicated low abundance of rarely reported HNPs (three hexachloro-1'-methyl-1,2'-bipyrrole (Cl6-MBP) isomers and pentabromo-1,1'-dimethyl-2,2'-bipyrroles (Br5-DBP)) but no further abundant unscreened polyhalogenated compounds.
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Produtos Biológicos , Oceano Índico , Moçambique , SeichelesRESUMO
The little information available on fuel consumption and emissions by high seas tuna fisheries indicates that the global tuna fleet may have consumed about 2.5 Mt of fuel in 2009, resulting in the production of about 9 Mt of CO2-equivalent greenhouse gases (GHGs), i.e., about 4.5-5% of the global fishing fleet emissions. We developed a model of annual fuel consumption for the large-scale purse seiners operating in the western Indian Ocean as a function of fishing effort, strategy, and vessel characteristics based on an original and unique data set of more than 4300 bunkering operations that spanned the period 2013-2019. We used the model to estimate the total fuel consumption and associated GHG and SO2 emissions of the Indian Ocean purse seine fishery between 1981 and 2019. Our results showed that the energetic performance of this fishery was characterized by strong interannual variability over the last four decades. This resulted from a combination of variations in tuna abundance but also changes in catchability and fishing strategy. In recent years, the increased targeting of schools associated with fish aggregating devices in response to market incentives combined with the IOTC management measure implemented to rebuild the stock of yellowfin tuna has strongly modified the productivity and spatio-temporal patterns of purse seine fishing. This had effects on fuel consumption and air pollutant emissions. Over the period 2015 to 2019, the purse seine fishery, including its support vessel component, annually consumed about 160,000 t of fuel and emitted 590,000 t of CO2-eq GHG. Furthermore, our results showed that air pollutant emissions can be significantly reduced when limits in fuel composition are imposed. In 2015, SO2 air pollution exceeded 1500 t, but successive implementation of sulphur limits in the Indian Ocean purse seine fishery in 2016 and 2018 have almost eliminated this pollution. Our findings highlight the need for a routine monitoring of fuel consumption with standardized methods to better assess the determinants of fuel consumption in fisheries and the air pollutants they emit in the atmosphere.
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Nitrogen and carbon stable isotope data sets are commonly used to assess complex population to ecosystem responses to natural or anthropogenic changes at regional to global spatial scales, and monthly to decadal timescales. Measured in the tissues of consumers, nitrogen isotopes (δ15 N) are primarily used to estimate trophic position while carbon isotopes (δ13 C) describe habitat associations and feeding pathways. Models of both δ15 N and δ13 C values and their associated variance can be used to estimate likely dietary contributions and niche width and provide inferences about consumer movement and migration. Stable isotope data have added utility when used in combination with other empirical data sets (e.g., stomach content, movement tracking, bioregionalization, contaminant, or fisheries data) and are increasingly relied upon in food web and ecosystem models. While numerous regional studies publish tables of mean δ15 N and δ13 C values, limited individual records have been made available for wider use. Such a deficiency has impeded full utility of the data, which otherwise would facilitate identification of macroscale patterns. The data provided here consist of 4,498 records of individuals of three tuna species, Thunnus alalunga, T. obesus, and T. albacares sampled from all major ocean basins from 2000 to 2015. For each individual tuna, we provide a record of the following: species name, sampling date, sampling location, tuna length, muscle bulk and baseline corrected δ15 N values, and muscle bulk and, where available, lipid corrected δ13 C values. We provide these individual records to support comparative studies and more robust modeling projects seeking to improve understanding of complex marine ecosystem dynamics and their responses to a changing environment. There are no copyright restrictions for research and/or teaching purposes. Users are requested to acknowledge their use of the data in publications, research proposals, websites, and other outlets following the citation instructions in Class III, Section B.
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Mercury, omega-3 (docosahexaenoic acid, DHA and eicosapentaenoic acid, EPA) and macronutrients (fat and proteins) were quantified on a wet weight (ww) basis in 20 species of fish taken as bycatch in tropical tuna fisheries. Based on a hazard quotient taking into account mercury and omega-3 contents, a benefit-risk assessment for the consumption of these pelagic species was conducted for three people categories: young children, children and adults. All fish bycatch were found to be an excellent source of proteins (minâmax = 14.4-25.2 g/100 g fillet), had low omega-6/omega-3 ratios (<1, except for silky shark), and had mercury content below the safety limits defined by sanitary agencies. Silky shark and Istiophoridae had the highest mercury contents (minâmax = 0.029-0.317 ppm ww). Omega-3 contents were the lowest in silky shark (0.2 ± 0.2 mg/100 g fillet) and the highest in striped marlin (3.6 ± 3.2 g/100 g fillet). Billfishes (Istiophoridae, including striped marlin), minor tunas (Scombridae), and Carangidae had the highest omega-3 contents (minâmax = 0.68-7.28 g/100 g fillet). The highest hazard quotient values obtained for silky shark and great barracuda reflected a lower nutritional benefit (i.e., low omega-3 source) than risk (i.e., mercury exposure), making them not advisable for consumption. Eight species had low hazard quotients, and among them cottonmouth jack and flat needlefish were found of high health interest (high protein, moderate fat contents, and low omega-6/omega-3 ratio). A daily serving portion of 85-200 g (according to people category) can be recommended for these species. Batfish, and to a lower extent pompano dolphinfish and brassy chub, can also be consumed safely and would provide greater health benefits than risks. These results advocate for a better access of these species to local populations.
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Mercúrio , Tubarões , Adulto , Animais , Criança , Pré-Escolar , Pesqueiros , Peixes , Humanos , Medição de Risco , Alimentos Marinhos , AtumRESUMO
Albacore tuna (Thunnus alalunga) is an important target of tuna fisheries in the Atlantic and Indian Oceans. The commercial catch of albacore is the highest globally among all temperate tuna species, contributing around 6% in weight to global tuna catches over the last decade. The accurate assessment and management of this heavily exploited resource requires a robust understanding of the species' biology and of the pattern of connectivity among oceanic regions, yet Indian Ocean albacore population dynamics remain poorly understood and its level of connectivity with the Atlantic Ocean population is uncertain. We analysed morphometrics and genetics of albacore (n = 1,874) in the southwest Indian (SWIO) and southeast Atlantic (SEAO) Oceans to investigate the connectivity and population structure. Furthermore, we examined the species' dispersal potential by modelling particle drift through major oceanographic features. Males appear larger than females, except in South African waters, yet the length-weight relationship only showed significant male-female difference in one region (east of Madagascar and Reunion waters). The present study produced a genetic differentiation between the southeast Atlantic and southwest Indian Oceans, supporting their demographic independence. The particle drift models suggested dispersal potential of early life stages from SWIO to SEAO and adult or sub-adult migration from SEAO to SWIO.
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Variação Genética , Atum/genética , Distribuição Animal , Animais , Oceano Atlântico , Oceano Índico , Modelos Estatísticos , Dinâmica PopulacionalRESUMO
Considerable uncertainty remains over how increasing atmospheric CO2 and anthropogenic climate changes are affecting open-ocean marine ecosystems from phytoplankton to top predators. Biological time series data are thus urgently needed for the world's oceans. Here, we use the carbon stable isotope composition of tuna to provide a first insight into the existence of global trends in complex ecosystem dynamics and changes in the oceanic carbon cycle. From 2000 to 2015, considerable declines in δ13 C values of 0.8-2.5 were observed across three tuna species sampled globally, with more substantial changes in the Pacific Ocean compared to the Atlantic and Indian Oceans. Tuna recorded not only the Suess effect, that is, fossil fuel-derived and isotopically light carbon being incorporated into marine ecosystems, but also recorded profound changes at the base of marine food webs. We suggest a global shift in phytoplankton community structure, for example, a reduction in 13 C-rich phytoplankton such as diatoms, and/or a change in phytoplankton physiology during this period, although this does not rule out other concomitant changes at higher levels in the food webs. Our study establishes tuna δ13 C values as a candidate essential ocean variable to assess complex ecosystem responses to climate change at regional to global scales and over decadal timescales. Finally, this time series will be invaluable in calibrating and validating global earth system models to project changes in marine biota.
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Fitoplâncton , Atum , Animais , Isótopos de Carbono , Ecossistema , Oceano Índico , Oceanos e Mares , Oceano PacíficoRESUMO
Various protocols are currently used to study marine lipids, but there is a growing interest in working on dry samples that are easier to transport. However, reference protocols are still lacking for dry samples. In order to make recommendations on this use, lipid classes and fatty acids (FA) obtained from six analytical protocols using two different tissue states (dry vs wet) and three extraction methods (automat vs manual potter vs leaving the solvent to work on tissue) were compared. Three dry storage modes of tissue (freezer vs gas nitrogen vs dry room) during one and three months were also compared. These comparisons were made on seven marine species with different lipid profiles, including fishes, crustaceans and mollusks. Lipid classes and FA obtained from wet and dry tissues were similar, but they were affected by the extraction methods. Regardless of tissue state, "Leave to work" methods obtained the highest lipid quantities, followed by manual potter and automat methods (ca. 90% and 80% of "Leave to work" methods, respectively). Linear relationships allowed correction for lipid classes and FA concentrations obtained from different protocols. The repeatability of all protocols still needs to be improved, especially for fish species. Increasing the replicate number for each sample might be an indirect way to improve lipid quantification. Our results show that storing dry tissues in the freezer for more than one month was associated with a decrease in lipids, which is also observed for other storage methods. For qualitative studies of FA (expressed in %), a three-month storage of dry tissue in freezer did not affect the relative composition of species/tissues with a lipid content below 20% of dry weight.
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Organismos Aquáticos/química , Fracionamento Químico/métodos , Ácidos Graxos/análise , Ácidos Graxos/isolamento & purificação , Preservação de Tecido/métodos , Animais , Liofilização , Temperatura , Clima TropicalRESUMO
Yellowfin tuna, Thunnus albacares, is one of the most important seafood commodities in the world. Despite its great biological and economic importance, conflicting evidence arises from classical genetic and tagging studies concerning the yellowfin tuna population structure at local and global oceanic scales. Access to more powerful and cost effective genetic tools would represent the first step towards resolving the population structure of yellowfin tuna across its distribution range. Using a panel of 939 neutral Single Nucleotide Polymorphisms (SNPs), and the most comprehensive data set of yellowfin samples available so far, we found genetic differentiation among the Atlantic, Indian and Pacific oceans. The genetic stock structure analysis carried out with 33 outlier SNPs, putatively under selection, identified discrete populations within the Pacific Ocean and, for the first time, also within the Atlantic Ocean. Stock assessment approaches that consider genetic differences at neutral and adaptive genomic loci should be routinely implemented to check the status of the yellowfin tuna, prevent illegal trade, and develop more sustainable management measures.