French Research Institute for Exploitation of the Sea
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Environmental Control of Oogenesis in a Potamodromous Neotropical Fish (Prochilodus Magdalenae)
No full textThe seasonal reproduction of teleost fish is modulated by the interaction between environmental factors, water physicochemistry, and their physiology. This study focused on the modulation of oogenesis by environmental cues in the Neotropical potamodromous fish Prochilodus magdalenae (bocachico). A total of 263 females were studied over one and a half reproductive cycles in three environments: the Swamp (72 samples) and River (83 samples), and aquaculture conditions (108 samples). Ovaries were histologically analyzed, plasma estradiol (E2) concentrations were measured, and six water physicochemical parameters (water temperature, total dissolved solids, conductivity, pH, dissolved oxygen, and oxygen saturation percentage) were monitored. Ovary development stages, from primary growth to final vitellogenesis (VtgB), occurred during the low rainfall season in Swamp, while oogenesis advanced to final maturation and synchronous spawning during the rainy season in the River. Under aquaculture conditions, however, ovaries reached the VtgB stage but did not progress to maturation or spawning. Plasmatic E2 levels were highest at the VtgB stage in aquaculture females (2384.5±324.5 pg/ml), significantly exceeding those in the Swamp (p= 0.0043) and River (p= 0.0001). Principal Component Analysis (PCA), followed by Generalized Additive Model (GAM) revealed that oogenesis is driven by multiple environmental cues, with the PCA explaining 87.3% and GAM 46.6% of data variability. The progression of oogenesis depends on non-linear interactions between environmental factors, seasonal variations, and habitat type. These findings provide critical insights for aquaculture and climate change, emphasizing how abiotic factors can impact reproductive processes and population dynamics
Questionnaire improvements in second-generation, multilingual decision support tools for invasion risk screening of non-native taxa
No full textAs a result of the increasing threats posed by non-native species invasions, there has been a rise in the demand for decision support tools that can more efficiently identify those non-native species likely to become invasive. As part of the risk screening (first) step in the environmental risk analysis process, three multilingual decision support tools are currently available for the screening of aquatic and terrestrial organisms: the Aquatic Species Invasiveness Screening Kit (AS-ISK), the Terrestrial Animal Species Invasiveness Screening Kit (TAS-ISK) and the Terrestrial Plant Species Invasiveness Screening Kit (TPS-ISK). Here, we describe the recent improvements to the questionnaire that forms the base of these second-generation Weed Risk Assessment-type tools. We subjected the AS-ISK and TAS-ISK questionnaires to a thorough revision and extended these improvements for the development of the TPS-ISK. Overall, this involved an improvement of the AS-ISK and TAS-ISK questionnaires, an alignment of the questionnaires across the three toolkits, and the translation of the three resulting questionnaires in all 30 non-English languages supported by the toolkits. Given the most extensive usage of the AS-ISK and, in perspective, of the recently released TAS-ISK and TPS-ISK, it is timely to provide researchers and decision-makers in the field of invasion biology with a suite of updated toolkits designed to streamline and improve the risk screening process. These enhancements will be crucial for the delivery of reports to stakeholders and decision-makers also in the languages supported by the toolkits as applicable, and in line with the ecology-of-language paradigm at the base of the toolkits’ multilingual interface development.
Record High Temperatures in the Ocean in 2024
No full textHeating in the ocean has continued in 2024 in response to increased greenhouse gas concentrations in the atmosphere, despite the transition from an El Niño to neutral conditions. In 2024, both global sea surface temperature (SST) and upper 2000 m ocean heat content (OHC) reached unprecedented highs in the historical record. The 0–2000 m OHC in 2024 exceeded that of 2023 by 16 ± 8 ZJ (1 Zetta Joules = 1021 Joules, with a 95% confidence interval) (IAP/CAS data), which is confirmed by two other data products: 18 ± 7 ZJ (CIGAR-RT reanalysis data) and 40 ± 31 ZJ (Copernicus Marine data, updated to November 2024). The Indian Ocean, tropical Atlantic, Mediterranean Sea, North Atlantic, North Pacific, and Southern Ocean also experienced record-high OHC values in 2024. The global SST continued its record-high values from 2023 into the first half of 2024, and declined slightly in the second half of 2024, resulting in an annual mean of 0.61°C ± 0.02°C (IAP/CAS data) above the 1981–2010 baseline, slightly higher than the 2023 annual-mean value (by 0.07°C ± 0.02°C for IAP/CAS, 0.05°C ± 0.02°C for NOAA/NCEI, and 0.06°C ± 0.11°C for Copernicus Marine). The record-high values of 2024 SST and OHC continue to indicate unabated trends of global heating
Rénovation de la gestion du saumon en Bretagne : le projet RENOSAUM
No full textPour réviser la gestion des populations de saumon en Bretagne, et plus particulièrement la régulation de leur exploitation par pêche à la ligne en rivière, l’OFB, INRAE et l’Université de Pau et Pays de l’Adour, en collaboration avec Bretagne Grands Migrateurs, ont œuvré conjointement dans le cadre d’un vaste exercice d’aide à la décision (projet RENOSAUM, 2017-2022). Ce travail est sans précédent par la quantité de données valorisées, la prise en compte des recommandations internationales et le dialogue continu entre scientifiques et acteurs de la gestion qui ont gouverné son déroulement. Il permet de disposer aujourd’hui, pour les 18 principales rivières à saumon bretonnes et sur plus de trois décennies (1987-2020), de connaissances inédites concernant l’abondance des juvéniles et des adultes, les mécanismes de renouvellement des générations au sein des populations étudiées, ainsi que leur régime d’exploitation par la pêche à la ligne. Elles ont servi de socle pour l’établissement de nouvelles limites de conservation pour chacune des populations étudiées, puis pour une analyse comparative d’un très large ensemble de scénarios de régulation de l’exploitation. Ce travail a conduit in fine à la mise en place de mesures de régulation renouvelées de l’exploitation par pêche à la ligne applicables à compter de 2023
If Vulcan was a primordial black hole of planetary-mass?
No full textIn this study, I re-examine the question of whether a hypothetical planet, Vulcan, could explain the anomalous advance of Mercury’s perihelion. I propose that Vulcan might be considered a type of primordial black hole with a planetary mass. The detection of this type of celestial body has become possible through modern experimental techniques, including the Optical Gravitational Lensing Experiment. Recently, an excess of ultra-short microlensing events with crossing times of 0.1–0.3 days has been reported, suggesting the possible existence of sub-Earth-mass primordial black holes in our solar system. The primordial black hole Vulcan planetary mass hypothesis could then explain the anomalous advance of Mercury’s perihelion under the influence of its gravitational attraction, remaining hidden from astronomers’ telescopes. But in this case, it will also influence the perihelion advance of the other planets. To this end, I first calculate the mutual partial contributions to the perihelion motion of all the planets by two different methods without Vulcan in a model of the simplified solar system consisting of the Sun and eight planets. Next, I include Vulcan in this model within the framework of the Newtonian theory of classical gravitation and analyze Vulcan’s influence on the perihelion advance of the inner planets, using Vulcan parameters from my previous work. These results are compared with the perihelion advances of the inner planets predicted by the theory of general relativity and with the data obtained by modern observations
Land Surface Temperature Super-Resolution with a Scale-Invariance-Free Neural Approach: Application to MODIS
No full textDue to the trade-off between the temporal and spatial resolution of thermal spaceborne sensors, super-resolution methods have been developed to provide fine-scale Land SurfaceTemperature (LST) maps. Most of them are trained at low resolution but applied at fine resolution, and so they require a scale-invariance hypothesis that is not always adapted. Themain contribution of this work is the introduction of a Scale-Invariance-Free approach for training Neural Network (NN) models, and the implementation of two NN models, calledScale-Invariance-Free Convolutional Neural Network for Super-Resolution (SIF-CNN-SR) for the super-resolution of MODIS LST products. The Scale-Invariance-Free approach consists ontraining the models in order to provide LST maps at high spatial resolution that recover the initial LST when they are degraded at low resolution and that contain fine-scale texturesinformed by the high resolution NDVI. The second contribution of this work is the release of a test database with ASTER LST images concomitant with MODIS ones that can be usedfor evaluation of super-resolution algorithms. We compare the two proposed models, SIF-CNN-SR1 and SIF-CNN-SR2, with four state-of-the-art methods, Bicubic, DMS, ATPRK, Tsharp,and a CNN sharing the same architecture as SIF-CNN-SR but trained under the scale-invariance hypothesis. We show that SIF-CNN-SR1 outperforms the state-of-the-art methods and the other two CNN models as evaluated with LPIPS and Fourier space metrics focusing on the analysis of textures. These results and the available ASTER-MODIS database for evaluation are promising for future studies on super-resolution of LST
Satellite altimetry and operational oceanography: from Jason-1 to SWOT
No full textThe development and evolution of satellite altimetry and operational oceanography are very closely linked. By providing all weather, global and real time observations of sea level, a key variable to constrain ocean analysis and forecasting systems, satellite altimetry has had a profound impact on the development of operational oceanography. Over the past 20 years, satellite altimetry has been providing a continuous observation of the ocean in near real time. From the launch of Jason-1 in 2001 to the launch of SWOT in 2022, satellite altimetry capabilities have regularly improved from geophysical corrections, processing algorithms including real time processing, altimeter radar technology (SAR mode, swath altimetry) and resolution thanks to the use of multiple altimeters and now swath altimetry. In parallel, major improvements of ocean prediction systems have occurred from the GODAE demonstration in the 2000s up to fully operational systems serving now a large range of applications in the 2020s. The paper provides an overview of the development and evolution of satellite altimetry and operational oceanography over the past 20 years in the context of the Mercator Ocean prediction center, the DUACS system and the EU Copernicus Marine Service. Impact of altimetry on the performances of ocean prediction systems (based on OSEs and OSSEs) is reviewed. The future contribution of swath altimetry on operational altimeter products and ocean prediction is also discussed. Prospects for the next decade are discussed in conclusion
ICES-FAO Working Group on Fishing Technology and Fish Behaviour (WGFTFB; outputs from 2024 meeting)
No full textHabitat and identification of scyphozoan polyps in Bages-Sigean lagoon (France)
No full textPolyps are important stage in the medusozoan jellyfish life cycle, but the ecology of wild populations is still poorly understood. For some species, like Rhizostoma pulmo, polyps have never been reported in the wild. The Bages-Sigean lagoon is a Mediterranean, semi-enclosed lagoon with seasonally abundant Aurelia coerulea and R. pulmo medusae. Given its semi-closed nature and because ephyrae are commonly observed, it is likely that the polyps of both species reside in the lagoon. Our study aimed to characterize the polyp species distribution for this lagoon by performing snorkeling surveys of the potential polyp substrates, such as wood, concrete, buoys and bivalves. We observed polyp colonies at five sites, all on the underside of floating polypropylene docks despite the diversity of available substrates. Identification of the jellyfish species was performed in two ways: by strobilation then development of the ephyrae in aquaria, and by DNA sequencing of the collected polyps. All five sites produced A. coerulea medusae, but we were unable to locate polyps of R. pulmo despite surveying substrates that the planulae settle on under laboratory conditions. This study underscores the need to improve our ability to locate polyps in the wild by expanding laboratory studies to include more species, increasing sampling efforts and substrates in the field, and applying new methods (e.g., eDNA, hydrodynamic modeling)