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AbstractEuropean small‐scale fisheries are confronted with several challenges, notably a decrease in the number of people engaged in capture fishing, growing competition from less expensive extra‐European Union markets, rising operational costs, strict regulations and the depletion of fishing stocks. Many small‐scale fishers must adapt to change to maintain or increase their income using different business strategies. In this respect, we argue that new and diversified institutional arrangements combined with building social capital can help reach long‐term economic sustainability for small‐scale fisheries businesses, as well as the social‐ecological resilience of coastal areas. In order to understand and analyse the multiplicity of strategies applied by small‐scale fishers–including expansion towards non–productivist activities, this article examines the role of new institutional arrangements based on small‐scale, traditional, quality‐orientated, multifunctional business strategies and non‐fishing activities. Using a case‐study approach, we analyse–in three different European fishery contexts (Greece, Italy and the UK)–how the interplay between building adaptive arrangements and the creation of social capital in selected small‐scale fisheries provides relevant prerequisites for resilience.

National audience; Les mécanismes impliqués dans le renouvèlement des cellules germinales souches chez les mâles immatures ou chez les individus adultes sexuellement matures restent très mal connus, en particulier chez les poissons. La production d'organoïdes testiculaires est une approche de choix pour étudier les interactions moléculaires entre les cellules somatiques et les cellules germinales ainsi que les modes de divisions symétriques et/ou asymétriques des cellules souches germinales. En effet, au contraire des cultures 2D, les organoïdes pourraient permettre de reproduire une niche germinale plus proche de celle rencontrée in vivo.

International audience

In most animals, sex determination occurs at conception, when sex chromosomes are segregated following Mendelian laws. However, in multiple reptiles and fishes, this genetic sex can be overridden by external factors after fertilization or birth. In some species, the genetic sex may also be governed by multiple genes, further limiting our understanding of sex determination in such species. We used the European sea bass (Dicentrarchus labrax) as a model and combined genomic (using a single nucleotide polymorphism chip) and transcriptomic (RNA-Sequencing) approaches to thoroughly depict this polygenic sex determination system and its interaction with temperature. We estimated genetic sex tendency (eGST), defined as the estimated genetic liability to become a given sex under a liability threshold model for sex determination, which accurately predicts the future phenotypic sex. We found evidence that energetic pathways, concerning the regulation of lipids and glucose, are involved in sex determination and could explain why females tend to exhibit higher energy levels and improved growth compared to males. Besides, early exposure to high-temperature up-regulated sox3, followed by sox9a in individuals with intermediate eGST, but not in individuals showing highly female-biased eGST, providing the most parsimonious explanation for temperature-induced masculinization. This gonadal state was maintained likely by DNA methylation and the up-regulation of several genes involved in histone modifications, including jmjd1c. Overall, we describe a sex determination system resulting from continuous genetic and environmental influences in an animal. Our results provide significant progress in our understanding of the mechanisms underlying temperature-induced masculinization in fish 12 pages, 6 figures, supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2112660118/-/DCSupplemental.-- Data Availability: RNA-Seq and .xls tables data have been deposited in a publicly accessible database: SEXTAN (https://sextant.ifremer.fr/record/5cb1485f-385e-46e9-9cc1-4b4d77802183/). All other study data are included in the article and/or supporting information The study was supported by the European Maritime and Fisheries Fund (3S, Seabass Sex and Stress, Grant No. 4320175237) allocated to B.G. Production of the fish benefited from AQUAEXCEL2020 Transnational access grant “Transsexbass” to F.P. and M.V. Research at the F.P. laboratory was supported by Spanish Ministry of Science Grant No. PID2019-108888RB-I00. With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S) Peer reviewed

Human exposure to toxic mercury (Hg) is dominated by the consumption of seafood1,2. Earth system models suggest that Hg in marine ecosystems is supplied by atmospheric wet and dry Hg(ii) deposition, with a three times smaller contribution from gaseous Hg(0) uptake3,4. Observations of marine Hg(ii) deposition and Hg(0) gas exchange are sparse, however5, leaving the suggested importance of Hg(ii) deposition6 ill-constrained. Here we present the first Hg stable isotope measurements of total Hg (tHg) in surface and deep Atlantic and Mediterranean seawater and use them to quantify atmospheric Hg deposition pathways. We observe overall similar tHg isotope compositions, with median Δ200Hg signatures of 0.02‰, lying in between atmospheric Hg(0) and Hg(ii) deposition end-members. We use a Δ200Hg isotope mass balance to estimate that seawater tHg can be explained by the mixing of 42% (median; interquartile range, 24–50%) atmospheric Hg(ii) gross deposition and 58% (50–76%) Hg(0) gross uptake. We measure and compile additional, global marine Hg isotope data including particulate Hg, sediments and biota and observe a latitudinal Δ200Hg gradient that indicates larger ocean Hg(0) uptake at high latitudes. Our findings suggest that global atmospheric Hg(0) uptake by the oceans is equal to Hg(ii) deposition, which has implications for our understanding of atmospheric Hg dispersal and marine ecosystem recovery. Mercury deposition pathways from the atmosphere to the ocean remain uncertain, but mercury stable isotope measurements from the Atlantic and Mediterranean show that ocean uptake of gaseous elemental mercury is more important than previously thought.

International audience; In temperate zones, energy reserves of fish are closely related to survival during the first winter of their life. In this study, the genetic and phenotypic background of the accumulation, mobilization and utilization of energy reserves was investigated in Amur mirror carp. To achieve this, the role of traits related to energy reserves on fish performance during the first winter and further periods of rearing was investigated. The experimental stock was established by four full-factorial matings of 5 dams and 10 sires to generate up to 200 full-sibling families. The offspring were sampled before and after the first winter rearing period. Seasonal variation in direct and indirect measures of energy status was examined using Fulton's condition factor (FC), hepato-somatic index (HSI), visceral index (VSI_NO), glycogen, fat and protein in hepatopancreas (HP) and muscle fat content. Other performance traits were also recorded (weight, resistance to koi herpesvirus disease). All traits related to energy reserves, except HP protein, were significantly lower after the first winter. Overall, HP glycogen and fat from muscle, HP and viscera were mobilized during winter. However, genetic correlations between same traits recorded in autumn and spring were lower than 0.8 for most of the traits, implying that not all families responded to overwintering in a similar manner. Heritability also differed before and after the first winter. Before the first winter, all traits had low to medium heritability (0.05-0.35), but after the winter the same traits were moderately or highly heritable (0.22-0.58). Interestingly, HP glycogen traits, unlike HP fat and HP protein, and HSI recorded in yearlings were positively genetically correlated with survival during the third growing season (rg = 0.49-0.72). This study provides the first evidence of a genetically based strategy for energy mobilization related to overwintering of common carp. Measuring of FC and HSI could be used to monitor the energy status of common carp and to provide a supplementary tool for management of carp stocks.

Abstract Elevated concentrations of atmospheric bromine are known to cause ozone depletion in the Arctic, which is most frequently observed during springtime. We implement a detailed description of bromine and chlorine chemistry within the WRF‐Chem 4.1.1 model, and two different descriptions of Arctic bromine activation: (1) heterogeneous chemistry on surface snow on sea ice, triggered by ozone deposition to snow (Toyota et al., 2011 https://doi.org/10.5194/acp-11-3949-2011), and (2) heterogeneous reactions on sea salt aerosols emitted through the sublimation of lofted blowing snow (Yang et al., 2008, https://doi.org/10.1029/2008gl034536). In both mechanisms, bromine activation is sustained by heterogeneous reactions on aerosols and surface snow. Simulations for spring 2012 covering the entire Arctic reproduce frequent and widespread ozone depletion events, and comparisons with observations of ozone show that these developments significantly improve model predictions during the Arctic spring. Simulations show that ozone depletion events can be initiated by both surface snow on sea ice, or by aerosols that originate from blowing snow. On a regional scale, in spring 2012, snow on sea ice dominates halogen activation and ozone depletion at the surface. During this period, blowing snow is a major source of Arctic sea salt aerosols but only triggers a few depletion events. Key Points Halogen activation and its role in Arctic surface ozone depletion events (ODEs) is modeled using WRF‐ChemTwo halogen activation mechanisms are implemented (1) surface snow and (2) blowing snowA spring 2012 case study indicates that both mechanisms can trigger near‐surface ODEs, but that surface snow dominates

AbstractCalcified coralline algae are ecologically important in rocky habitats in the marine photic zone worldwide and there is growing concern that ocean acidification will severely impact them. Laboratory studies of these algae in simulated ocean acidification conditions have revealed wide variability in growth, photosynthesis and calcification responses, making it difficult to assess their future biodiversity, abundance and contribution to ecosystem function. Here, we apply molecular systematic tools to assess the impact of natural gradients in seawater carbonate chemistry on the biodiversity of coralline algae in the Mediterranean and the NW Pacific, link this to their evolutionary history and evaluate their potential future biodiversity and abundance. We found a decrease in the taxonomic diversity of coralline algae with increasing acidification with more than half of the species lost in high pCO2 conditions. Sporolithales is the oldest order (Lower Cretaceous) and diversified when ocean chemistry favoured low Mg calcite deposition; it is less diverse today and was the most sensitive to ocean acidification. Corallinales were also reduced in cover and diversity but several species survived at high pCO2; it is the most recent order of coralline algae and originated when ocean chemistry favoured aragonite and high Mg calcite deposition. The sharp decline in cover and thickness of coralline algal carbonate deposits at high pCO2 highlighted their lower fitness in response to ocean acidification. Reductions in CO2 emissions are needed to limit the risk of losing coralline algal diversity.