Anthropogenic boat noise reduces feeding success in winter flounder larvae (Pseudopleuronectes americanus)

The aim of this study was to explore an emerging discipline addressing the impact of anthropogenic noise on larval stages of marine organisms. We assessed the influence of boat noise on the feeding behaviour of the pelagic larvae of winter flounder (Pseudopleuronectes americanus, Walbaum, 1792). The hypothesis was that boat noise influences the feeding behaviour of P. americanus flounder larvae independently of prey density. Aquaria containing P. americanus larvae were placed in water baths in which boat noise was diffused for the “noise” treatment and compared to control aquaria with no sound emissions. Larvae were filmed using cameras placed above the aquaria and their behaviour was recorded. Larvae exposed to anthropogenic noise displayed significantly fewer hunting events than controls, and their stomach volumes were significantly smaller. This noise effect was the same at all prey densities used, suggesting that larval feeding behaviour is negatively impaired by anthropogenic noise. Keywords : Feeding behaviour ; Winter flounder ; Larvae ; Anthropogenic noise ; Vessel noise

New insights on the population genetic structure of the great scallop (Pecten maximus) in the English Channel coupling microsatellite data and demogenetic simulations.

International audienceThe great scallop (Pecten maximus) is a commercially important bivalve in Europe, particularly in the English Channel, where fisheries are managed at regional and local scales through the regulation of fishing effort. In the long term, knowledge about larval dispersal and gene flow between populations is essential to ensure proper stock management. Yet, previous population genetic studies have reported contradictory results. In this study, scallop samples collected across the main fishing grounds along the French and English coasts of the English Channel (20 samples with temporal replicates for three sites,n= 1059 individuals), and the population genetic structure was analysed using 13 microsatellite loci. Coupling empirical genetic data with demogenetic modelling based on a biophysical model simulating larval exchanges among scallop beds revealed a subtle genetic differentiation between south-west English populations and the rest of the English Channel, which was consistent with larval dispersal simulations. The present study provides a step forward in the understanding of great scallop population biology in the English Channel, underlining the fact that even in a context of potentially high gene flow and recent divergence times since the end of the last glacial maximum, weak but significant spatial genetic structure can be identified at a regional scale

Variation in Size and Growth of the Great Scallop Pecten maximus along a Latitudinal Gradient

Understanding the relationship between growth and temperature will aid in the evaluation of thermal stress and threats to ectotherms in the context of anticipated climate changes. Most Pecten maximus scallops living at high latitudes in the northern hemisphere have a larger maximum body size than individuals further south, a common pattern among many ectotherms. We investigated differences in daily shell growth among scallop populations along the Northeast Atlantic coast from Spain to Norway. This study design allowed us to address precisely whether the asymptotic size observed along a latitudinal gradient, mainly defined by a temperature gradient, results from differences in annual or daily growth rates, or a difference in the length of the growing season. We found that low annual growth rates in northern populations are not due to low daily growth values, but to the smaller number of days available each year to achieve growth compared to the south. We documented a decrease in the annual number of growth days with age regardless of latitude. However, despite initially lower annual growth performances in terms of growing season length and growth rate, differences in asymptotic size as a function of latitude resulted from persistent annual growth performances in the north and sharp declines in the south. Our measurements of daily growth rates throughout life in a long-lived ectothermic species provide new insight into spatio-temporal variations in growth dynamics and growing season length that cannot be accounted for by classical growth models that only address asymptotic size and annual growth rate

A High Throughput Genetic Screen Identifies New Early Meiotic Recombination Functions in Arabidopsis thaliana

Meiotic recombination is initiated by the formation of numerous DNA double-strand breaks (DSBs) catalysed by the widely conserved Spo11 protein. In Saccharomyces cerevisiae, Spo11 requires nine other proteins for meiotic DSB formation; however, unlike Spo11, few of these are conserved across kingdoms. In order to investigate this recombination step in higher eukaryotes, we took advantage of a high-throughput meiotic mutant screen carried out in the model plant Arabidopsis thaliana. A collection of 55,000 mutant lines was screened, and spo11-like mutations, characterised by a drastic decrease in chiasma formation at metaphase I associated with an absence of synapsis at prophase, were selected. This screen led to the identification of two populations of mutants classified according to their recombination defects: mutants that repair meiotic DSBs using the sister chromatid such as Atdmc1 or mutants that are unable to make DSBs like Atspo11-1. We found that in Arabidopsis thaliana at least four proteins are necessary for driving meiotic DSB repair via the homologous chromosomes. These include the previously characterised DMC1 and the Hop1-related ASY1 proteins, but also the meiotic specific cyclin SDS as well as the Hop2 Arabidopsis homologue AHP2. Analysing the mutants defective in DSB formation, we identified the previously characterised AtSPO11-1, AtSPO11-2, and AtPRD1 as well as two new genes, AtPRD2 and AtPRD3. Our data thus increase the number of proteins necessary for DSB formation in Arabidopsis thaliana to five. Unlike SPO11 and (to a minor extent) PRD1, these two new proteins are poorly conserved among species, suggesting that the DSB formation mechanism, but not its regulation, is conserved among eukaryotes

Rapid response to the M_w 4.9 earthquake of November 11, 2019 in Le Teil, Lower Rhône Valley, France

On November 11, 2019, a Mw 4.9 earthquake hit the region close to Montelimar (lower Rhône Valley, France), on the eastern margin of the Massif Central close to the external part of the Alps. Occuring in a moderate seismicity area, this earthquake is remarkable for its very shallow focal depth (between 1 and 3 km), its magnitude, and the moderate to large damages it produced in several villages. InSAR interferograms indicated a shallow rupture about 4 km long reaching the surface and the reactivation of the ancient NE-SW La Rouviere normal fault in reverse faulting in agreement with the present-day E-W compressional tectonics. The peculiarity of this earthquake together with a poor coverage of the epicentral region by permanent seismological and geodetic stations triggered the mobilisation of the French post-seismic unit and the broad French scientific community from various institutions, with the deployment of geophysical instruments (seismological and geodesic stations), geological field surveys, and field evaluation of the intensity of the earthquake. Within 7 days after the mainshock, 47 seismological stations were deployed in the epicentral area to improve the Le Teil aftershocks locations relative to the French permanent seismological network (RESIF), monitor the temporal and spatial evolution of microearthquakes close to the fault plane and temporal evolution of the seismic response of 3 damaged historical buildings, and to study suspected site effects and their influence in the distribution of seismic damage. This seismological dataset, completed by data owned by different institutions, was integrated in a homogeneous archive and distributed through FDSN web services by the RESIF data center. This dataset, together with observations of surface rupture evidences, geologic, geodetic and satellite data, will help to unravel the causes and rupture mechanism of this earthquake, and contribute to account in seismic hazard assessment for earthquakes along the major regional Cévenne fault system in a context of present-day compressional tectonics

Compréhension des mécanismes de biominéralisation (quantification spatialisée des fractions minérale et organique et influence de facteurs environnementaux)

Malgré un grand nombre d études relatives à l utilisation des otolithes, les connaissances sur les mécanismes de formation de l otolithe et leur modulation par les facteurs environnementaux et physiologiques restent parcellaires. En particulier, la caractérisation des fractions minérale et organique des structures de I otolithe et l influence de leurs propriétés qualitatives et quantitatives sur l opacité restent peu documentées, Pourtant ces informations sont d importance en vue d une calibration robuste de l archive otolithe . Le premier axe de recherche s est concentré sur l opacité et les effets de la température, la croissance et du métabolisme à partir d expérimentation en milieu contrôlé. L opacité a ainsi été définie comme une fonction de deux contributions énergétiques: l une relative à la croissance somatique et l autre indépendante de la croissance somatique et associée à des mécanismes de maintenance. Le second axe de recherche s est focalisé sur l analyse des propriétés physico-chimiques des structures de l otolithe. Le développement d une approche de micro-spectrométrie Raman, non destructive, nous a permis de discriminer de manière quantitative des signatures organique et minérale à une très haute résolution. La caractérisation de micro et macrostructures a permis la construction d un modèle de prédiction de l opacité en fonction des signatures de ces deux fractions. Si la relation entre facteurs modulant la biominéralisation et caractéristiques physicochimiques des structures reste à établir, les résultats obtenus dans cette thèse ouvrent de pistes prometteuses pour une meilleure compréhension des mécanismes de formation de l otolithe.Despite numerous applications on the use of otoliths at both population and individual levels, knowledge regarding the mechanisms of the otolith and their variations with environmental and physiological factors has to be improved. In particular, the characterization of mineral and organic fractions of the otolith structures and the influence of their qualitative and quantitative composition on the opacity remain poorly documented. Vet this information is of key interest for the calibration of the archive otolith allowing a robust analysis of information. The first issue of this study focused on the analysis of the opacity and the effects of temperature, growth and metabolism through experiments in controlled conditions. Results led to the modelling of opacity as a function of two energetic contributions: one related to somatic growth and the other independent of somatic growth and associated to maintenance mechanisms. The second issue dealt with the physico-chemical characterization of otolith structures. The development of an approach based on micro-spectrometry Raman, non-destructive, has allowed to quantitatively discriminating organic and mineral signatures at very high resolution. It has led to the characterization of microstructures (L and D zones) and macrostructures (translucent and opaque zones) led to the development of a predictive model of opacity from the signatures of these two fractions. The relationship between the environmental and metabolic factors and the chemical composition of structural features has still to be established but our results promising perspectives for a better understanding of the mechanisms of otolith biomineralisation.BREST-BU Droit-Sciences-Sports (290192103) / SudocPLOUZANE-Bibl.La Pérouse (290195209) / SudocSudocFranceF

Impacts des sons anthropiques sur la faune marine

International audienceLoin du monde du silence, le milieu marin doit se concevoir comme un environnement sonore. L’océan est porteur de bruits d’origine physique (vagues, pluie, glace, séismes) et biologiques (chant des baleines, clics des dauphins, claquements de crevettes ou d’oursins). Ce paysage acoustique est essentiel pour la faune marine. Il participe, entre autres, à l’orientation des larves, à la communication des animaux entre eux, à la détection de prédateurs. Toutefois, depuis un peu plus d’un siècle, les activités humaines modifient grandement ce paysage acoustique. Les bruits d’origine anthropique proviennent des navires, des installations posées en mer, des sonars et plus récemment de l’utilisation des énergies marines renouvelables. La faune marine perçoit-elle ces nouveaux sons ? La question de l’impact des sons anthropiques sur la faune marine se révèle un enjeu écologique et économique majeur pour les années à venir. Les auteurs montrent la diversitéde leurs effets sur la faune grâce à une approche multidisciplinaire associant la physique, la réglementation, la biologie et l’étude d’impact ; une place particulière est donnée aux premiers retours d’expérience de production d’énergies marines renouvelables (EMR) en Europe. Cet ouvrage se veut un premier état des lieux d’un champ de recherche qui ne fait que commencer

Diel rhythm in diving behaviour of european hake and associated thermal changes revealed by archival tagging

International audience

nouvelle édition augmentée

Le défi de l'éthique dans l'entreprise relève-t-il de l'angélisme, d'une bonne stratégie organisationnelle ou encore d'une nouvelle régulation du système capitaliste ? L'entreprise ne s'est jamais contentée d'un rôle strictement économique : l'histoire montre qu'elle a été au centre des mécanismes de régulation et de cohérence sociales à travers le paternalisme ou la quête d'une entreprise citoyenne. Mais désormais la mondialisation, le désengagement de l'Etat, les nouvelles technologies conduisent l'entreprise à prendre de nouvelles responsabilités, ne serait-ce qu'en matière environnementale. L'entreprise doit de plus en plus se soucier d'éthique. Mais est-ce compatible avec le profit ? S'agit-il d'une responsabilité individuelle ou collective ? Comment l'évaluer ? Autant de questions qui trouvent leur réponse dans l'action. L'agir éthique implique des relations basées sur la confiance. Il a de multiples aspects dans l'entreprise : ressources humaines, marketing, finance, production... Et à l'extérieur de l'entreprise, il concerne les fournisseurs, les clients, l'écologie, le chômage, le commerce international... Cet ouvrage passe en revue les débats théoriques et les pratiques et, à partir d'une approche historique, propose un renouvellement des questions que pose l'éthique à l'entreprise