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The specific stock composition and dispersion of anadromous fish species aggregations in the marine environment are poorly known, while they can play a major role in the metapopulation dynamics. Otolith microchemistry has proven to be a powerful tool to address natal origins of anadromous fish. We used archived otolith microchemistry to investigate the population-specific composition of subadult European shads (Alosa alosa and Alosa fallax) in the ocean during the 1980s. The allocation of natal origin was addressed relying on contemporary water and juveniles' signatures within a Bayesian model. A great discrimination of natal origin was obtained at the Biscay Gulf scale. However, the discrimination of 1980s natal origin for the southern rivers with similar geology based on 2013 water and juveniles' baselines was doubtful. Our results showed that the most abundant southern populations were dominant, suggesting that population-specific composition was related to population relative abundance. The dispersion in the marine environment was plastic; alternatively, shads were found large distances away from their natal rivers, while others remained in the vicinity of their natal river plume. La composition specifique de stocks et la dispersion de regroupements d'especes de poissons anadromes dans le milieu marin demeurent meconnues, bien qu'elles puissent jouer un important role dans la dynamique de metapopulation. La microchimie des otolithes s'avere etre un outil puissant pour examiner les origines natales de poissons anadromes. Nous utilisons la microchimie d'otolithes archives pour examiner la composition propre a la population d'aloses europeennes (Alosa alosa and Alosa fallax) sous-adultes dans l'ocean dans les annees 1980. L'affection de l'origine natale repose sur des signatures d'eau et de juveniles contemporaines dans un modele bayesien. Une excellente discrimination de l'origine natale est obtenue a l'echelle du golfe de Gascogne. Cependant, la discrimination de l'origine natale dans les annees 1980 pour les rivieres meridionales de geologie semblable basee sur des donnees de reference de 2013 pour l'eau et les juveniles est incertaine. Nos resultats montrent que les populations meridionales les plus abondantes etaient dominantes, donnant a penser que la composition propre a la population etait reliee a l'abondance relative des populations. La dispersion dans le milieu marin est plastique; des aloses se trouvaient a grande distance de leurs rivieres natales, alors que d'autres demeuraient a proximite du panache de leur riviere natale. [Traduit par la Redaction], Introduction Anadromous fish species, such as salmons and shads, share a complex life cycle where reproduction and early life are undertaken in freshwater habitats, whereas growth and maturation are achieved [...]

Although otoliths are widely used as archives to infer life‐history traits and habitat use in fishes, their biomineralization process remains poorly understood. This lack of knowledge is problematic as it can lead to misinterpretation of the different types of signals (e.g., optical or chemical) that provide basic data for research in fish ecology, fisheries management, and species conservation. Otolith calcification relies on a complex system involving a pericrystalline fluid, the endolymph, whose organic and inorganic compositions are spatially heterogeneous for some constituents. This property stems from the particular structure of the calcifying saccular epithelium. In this study, we explored the spatial heterogeneity of elemental incorporation in otoliths for two species of high economic interest, European hake Merluccius merluccius (L. 1758) and European sea bass Dicentrarchus labrax (L. 1758). Two‐dimensional mappings of chemical elements were obtained using UV high‐repetition‐rate femtosecond laser ablation (fs‐LA) system coupled to a high‐resolution inductively coupled plasma sector field mass spectrometer analyses on transverse sections of sagittae. Results highlighted a clear asymmetry between proximal (sulcus) and distal (antisulcus) concentrations for elements such as magnesium (Mg), phosphorus (P), manganese (Mn), and potassium (K) with concentration gradient directions that varied depending on the element. Strontium (Sr) and barium (Ba) did not show a proximo‐distal gradient. These results are discussed in light of current knowledge on the endolymph composition and the mechanisms that lead to its compartmentalization, highlighting the need for further research on otolith biomineralization. Operational implications for studies based on otolith chemical composition are also discussed with emphasis on advice for sampling strategies to avoid analytical biases and the need for in‐depth analyses of analytical settings before comparing otolith signatures between species or geographical areas. [ABSTRACT FROM AUTHOR]

Understanding dispersal capacities for migratory species is crucial for their management. By coupling otolith microchemistry and microsatellite genetic analyses, we provided information on snapshot and long-term dispersal capacity of Allis shad (Alosa alosa), an anadromous clupeid in decline throughout its distribution range. The allocation of natal origin was obtained from water chemistry and signatures in otoliths of juveniles and spawners within a Bayesian model. The majority of adults were assigned to a source river with high degrees of confidence; only 4% were undetermined. Otolith natal origins were used to define a population baseline by grouping individuals from the same natal river and not from the same sampling location as usually done. While A. alosa exhibited a high level of natal site fidelity, this species showed weak genetic structure, which supported the evidence of a substantial flow of strayers between river basins in the vicinity or at longer distances. However, long distance straying was probable but not frequent. In a context of global change, straying would be a key mechanism to drive dispersal and allow resilience of Allis shad populations. La comprehension des capacites de dispersion des especes migratrices est d'importance capitale pour leur gestion. En jumelant la microchimie des otolithes aux analyses genetiques reposant sur les microsatellites, nous avons obtenu de l'information sur la capacite de dispersion immediate et a long terme de l'alose vraie (Alosa alosa), un poisson clupeide anadrome en declin dans toute son aire de repartition. L'affectation de l'origine natale a ete etablie sur la base de la signature de l'eau et des signatures d'otolithes d'individus juveniles et matures au sein d'un modele bayesien. La majorite des adultes a ete affectee a une riviere source avec des degres de confiance eleves, et seulement 4% des individus etaient d'origine indeterminee. L'origine natale obtenue des otolithes a ete utilisee pour definir une ligne de base des populations en regroupant les individus de la meme riviere natale plutot que du meme lieu d'echantillonnage, comme cela se fait habituellement. Si A. alosa faisait preuve d'un degre eleve de fidelite au site natal, cette espece presentait une structure genetique faible, ce qui appuie les indices d'un flux significatif d'individus egares entre bassins versants rapproches ou plus eloignes. Cependant, l'egarement sur de grandes distances etait probable, mais pas frequent. Dans un contexte de changements planetaires, l'egarement constituerait un important mecanisme de dispersion qui confererait de la resilience aux populations d'aloses vraies. [Traduit par la Redaction], Introduction Understanding population structure and connectivity for migratory species across broad geographic areas (e.g., species' distribution) is of major interest for their management and conservation. Anadromous fish are defined by [...]

We investigated the use of Sr:Ca, Ba:Ca, and [sup.87]Sr: [sup.86]Sr ratios as natural tags for determining the natal origins of juvenile and adult Atlantic salmon (Salmo salar) from 12 tributaries in the Adour basin (southwestern France) and estimated homing on a tributary scale. Geochemical signatures from core regions of the otolith were also used to identify fish from hatchery or naturally spawned sources. Quadratic discriminant function analysis (QDFA) was on average 80% successful at classifying juveniles according to their natal rivers. Adults of unknown natal origin were assigned to their natal rivers using the juvenile fingerprints from QDFA approach. Only 18 adults originated from streams not included in the juvenile database. Although most of the adults showed a marked homing instinct, homing was not perfect, and some wild fish strayed into non-natal spawning areas. Returns of hatchery-reared fish as adult spawners represented 10% of the total sampled fish. Allocation of fish to natal tributaries or hatcheries illustrated the abundance and relative contributions of natal sources, important for the recovery of Atlantic salmon in this area. Nous nous sommes penches sur l'utilisation des rapports Sr:Ca, Ba:Ca et [sup.87]Sr: [sup.86]Sr comme marqueurs naturels des origines natales de saumons atlantiques juveniles et adultes provenant de 12 affluents du bassin de l'Adour (sud-ouest de la France) et avons estime le retour a l'echelle des affluents. Les signatures geochimiques des regions centrales d'otolithes ont egalement ete utilisees pour distinguer les poissons issus d'ecloseries de ceux issus du frai en milieu naturel. Le taux de succes moyen de l'analyse discriminante quadratique (QDFA) pour ce qui est de classer les juveniles selon leurs rivieres natales etait de 80 %. La determination de la riviere natale des adultes d'origine natale inconnue reposait sur les empreintes de juveniles tirees de la QDFA. Seuls 18 adultes provenaient de cours d'eau ne figurant pas dans la base de donnees des juveniles. Bien que la plupart des adultes presentaient un instinct de retour marque, le retour n'etait pas parfait, certains poissons sauvages se retrouvant dans des regions de frai non natales. Les poissons eleves en ecloserie retournant comme geniteurs adultes representaient 10 % du total des poissons echantillonnes. La repartition des poissons entre affluents natals et ecloseries illustre l'abondance et les contributions relatives des sources natales, qui jouent un role important dans le retablissement du saumon atlantique dans la region. [Traduit par la Redaction], Introduction Identifying the natal origins of Atlantic salmon is one of the most attractive aspects of understanding the population structure of this highly migratory fish. Such information is beneficial to [...]

This study combines otolith trace element and genetic analyses to explore the origin of individuals when hatcheryreared fish are released into wild populations. We sampled 90 juvenile Atlantic salmon (Salmo salar) in four rivers in Normandy (France) and in the hatchery stock. Individuals were analyzed at six microsatellite markers and their otolith elemental concentrations (14 elements) were measured using femto-second laser ablation inductively-coupled plasma mass spectrometry. Wild populations were genetically differentiated from the hatchery strain ([F.sub.ST] ≅ 0.06). Significant differences in elemental concentrations were found among otoliths of juveniles from the four rivers and the hatchery, allowing the identification of their geographic origin (83%-100% correct assignment). Coupling genetic and trace element analyses on the same individuals provided formal evidence that hatchery-born juveniles released into the wild can migrate to the sea and return as adults to breed on natural spawning grounds. Their progeny have pure hatchery pedigrees but have otoliths typical of riverborn juveniles, meaning that they can be mistaken for hatchery-raised juveniles if only genetic data are considered. The presence of hybrids also confirmed that individuals with hatchery pedigrees can breed with wild conspecifics. Notre etude combine des analyses d'elements en trace dans les otolithes et des analyses genetiques pour determiner l'origine des individus lorsque des poissons eleves en pisciculture sont relaches dans des populations sauvages. Nous avons preleve 90 jeunes saumons atlantiques (Salmo salar) dans quatre rivieres de Normandie (France) et dans le stock de pisciculture. Chez ces individus, nous avons analyse six marqueurs microsatellites et determine les concentrations en elements (14 elements) de leurs otolithes par spectrometrie de masse a plasma a couplage inductif avec ablation au laser femtoseconde. Generalement, les populations sauvages se differencient genetiquement de la souche de pisciculture (FST ≅ 0,06). Il existe des differences significatives dans les concentrations d'elements dans les otolithes des jeunes des quatre rivieres et de la pisciculture, ce qui permet l'identification de leur origine geographique (83-100 % des assignations correctes). Le couplage des analyses genetiques et des dosages d'elements en trace sur les memes individus fournit des preuves formelles que les jeunes nes en pisciculture et liberes en nature peuvent migrer en mer et revenir comme adultes se reproduire sur les sites naturels de fraie. Leurs rejetons possedent des pedigrees purs de pisciculture mais des otolithes typiques de jeunes nes en riviere, ce qui veut dire qu'ils peuvent etre confondus avec des jeunes eleves en pisciculture, si on ne considere que les donnees genetiques. La presence d'hybrides confirme de plus que des individus possedant un pedigree de pisciculture peuvent se reproduire avec des poissons sauvages de meme espece. [Traduit par la Redaction], Introduction The supplementation of wild populations with hatcheryreared individuals is a common practice in salmonid fisheries management (Aprahamian et al. 2003; Fraser 2008). The mortality of stocked fish is often [...]

A new approach was demonstrated for the isotope ratio measurement in different elemental species of Hg using transient signal obtained by chromatography coupled with multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS). The method based on the slope of linear regression by transient intensities of different isotopes shows improved accuracy and reproducibility (0.2-0.5 [per thousand] as 2 standard deviation (SD)). Internal precision (RSD) of the method is very close to the theoretical value given by the counting statistic and is better by a factor of 6 in comparison with previous conventional methods of calculation. We demonstrated that internal RSD (uncertainty) depends on regression coefficients of the linear function ([R.sup.2]). The typical internal precision of isotopic ratio measurements (0.003-0.02%) was achieved for [delta][sup.202]Hg when injecting as low as 90 pg of Hg species. With the new methodology, it is possible to (i) measure the isotopic composition when a sample and a bracketing standard have significantly different concentrations, (ii) measure the isotopic composition of different species in samples versus single species in a bracketing standard, and (iii) measure the isotopic ratios for low abundant isotopes. We demonstrated application of this method for different environmental samples and processes. 10.1021/ac100648f

A method has been developed for the direct and simultaneous multielement determination of Cu, Zn, Sn, and Pb in soil and sediment samples using femtosecond laser ablation inductively coupled plasma mass spectrometry (fs-LA-ICPMS) in combination with isotope dilution mass spectrometry (IDMS). The in-cell isotope dilution fs-LA-ICPMS method proposed in this work was based on the quasi-simultaneous ablation of the natural abundance sample and the isotopically enriched solid spike, which was performed using a high repetition rate laser and a fast scanning beam device in a combined manner. Both the sample preparation procedure and the total analysis time have been drastically reduced, in comparison with previous approaches, since a unique multielement isotopically enriched solid spike was employed to analyze different powdered samples. Numerous experimental parameters were carefully selected (e.g., carrier gas flow rate, inlet diameter of the ablation cell, sample translation speed, scanner speed, etc.) in order to ensure the complete mixing between the sample and the solid spike aerosols. The proposed in-cell fs-LA-ICP-IDMS method was tested for the analysis of two soil (CRM 142R, GBW-07405) and two sediment (PACS-2, IAEA-405) reference materials, and the analysis of Cu, Zn, Sn, and Pb yielded good agreement of usually not more than 10% deviation from the certified values and precisions of less than 15% relative standard deviation. Furthermore, the concentrations were in agreement not only with the certified values but also with those obtained by ICP-IDMS after the microwave-assisted digestion of the solid samples, demonstrating therefore that in-cell fs-LA-ICP-IDMS opens the possibility for accurate and precise determinations of trace elements in powdered samples reducing the total sample preparation time to less than 5 min. Additionally, scanning electron microscope measurements showed that the aerosol generated by in-cell fs-LA-ICP-IDMS predominantly consisted of linear agglomerates of small particles (in the order of few tens of nanometers) and a few large spherical particles with diameters below 225 nm.

A laser ablation-ICPMS method using an infrared (1030 nm), low-energy (39 [micro]J/pulse), high repetition rate (10 kHz), femtosecond laser was developed to improve the sensitivity of detection of heteroatom-containing proteins in 1D polyacrylamide gels. A 2-mm-wide lane was ablated by ultrafast (10 cm [s.sup.-1]) back-and-forth movement of a 20-[micro]m laser beam parallel to the protein bands while the gel advanced perpendicularly. This procedure resulted in a considerable increase in detection sensitivity (> 40-fold) compared to the nanosecond 266-nm laser ablationICPMS, mainly because of the much larger amount of ablated material introduced into the plasma on the time scale of the dwell time of the mass spectrometer. The method was applied to the specific detection in the gel of formate dehydrogenase expressed in Escherichia coli and of selenoproteins in Desulfococcus multivorans with detection limits at the low-femtomolar levels.