HAL Université des Antilles
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Transmission des savoirs et succession de l’entreprise familiale. Comment les outils digitaux permettent de réduire les biais affectifs et cognitifs des prédécesseurs et des successeurs
No full textInternational audienc
Comment une forêt peut-elle émettre plus de CO₂ qu’elle n’en capture ?
No full textArticle de vulgarisation traitant de la dynamique des émissions de carbone par les forêts du globe.Forests are often considered as precious "carbon sinks" absorbing a part of the excess CO2 in the atmosphere, but this role is fading today.Some forests now emit more CO2 than they can capture. This phenomenon has multiple causes: global changes, anthropic pressures and their consequences.Longtemps considérées comme de précieux « puits de carbone » absorbant une partie du CO2 en excès dans l’atmosphère, les forêts voient aujourd’hui ce rôle fragilisé. Certaines émettent désormais plus de CO2 qu’elles n’en captent. La cause de ce phénomène est multiple : elle tient au changement climatique, aux pressions anthropiques et à leurs conséquences
Morphometric study of the bony labyrinth of the inner ear in the European moles <i>Talpa europaea</i>, <i>Talpa occidentalis</i>, and <i>Talpa aquitania</i>
No full textInternational audienceThe inner ear, particularly the semicircular canals system, plays a crucial role in balance and spatial navigation. It has previously been investigated to understand if its shape is related to the ecology: it is indeed known to be a good predictor for the extreme ecological niche of burrowing or arboreal organisms, although being strongly driven by the phylogeny. Recent phylogenetic studies of European moles have revealed the paraphyletic status of the species Talpa europaea and the description of new parapatric species in south-western Europe. Following the description of the new mole species Talpa aquitania, its forelimb morphology has been compared to those of its two sister species, Talpa europaea and Talpa occidentalis, revealing inter- and intra-specific morphological discrimination. The present study aims to compare the morphologies of the semicircular canal system in these three sister species of moles. Geometric morphometrics was used on 58 specimens representing the three species to analyze shape-related information and quantify the variability. The results demonstrate interspecific variability in the shape of the semicircular canals within the three species and intraspecific variability across sampling sites. Furthermore, no sexual dimorphism was observed for the bony labyrinth. The observed variability is likely influenced by the distinct ecological characteristics of the habitats housing the three Talpa species and their populations or by genetic differences resulting from their evolutionary history
Insights into the in vitro ichthyotoxicity on fish gill cells and toxin production of Karlodinium veneficum (Dinophyceae) strains from French waters
No full textInternational audienceThe dinoflagellate Karlodinium veneficum is regularly detected in French coastal waters; however, the ichthyotoxic potential of French strains and their ability to produce karlotoxins (KmTxs) remain unclear. This study aims to compare the bioactivity and KmTx profiles of four French strains and one previously characterized American strain of K. veneficum (used here as a reference), using the RTgill-W1 rainbow trout gill cell line. Both intracellular and releasable toxins (INT, EXT) in methanolic extracts were assessed for their effects using a resazurin-based assay, lactate dehydrogenase (LDH) release, mitochondrial membrane potential (TMRE dye), while liquid chromatography coupled to mass spectrometry was used to detect KmTxs. Cytotoxic activity varied depending on the strain and fraction, with IFR-CC-20–44 EXT (French) and CCMP 2936 INT (American) being the most toxic, while CBC7 (French) showed no toxicity. The French strains generally exhibited different cytotoxic mechanisms compared to the American strain. The KmTx profiles of the toxic strains showed an unexpectedly high chemodiversity with 93 KmTx-like molecules detected. Three French strains had similar KmTx profiles, dominated by KmTx-5 and a KmTx-5 analog. In contrast, the KmTx profile of the American CCMP 2936 was completely different to the French strains, with no KmTx in common. Interestingly, strain CBC7, which was non-toxic, did not produce any KmTxs. However, among the other K. veneficum strains, no clear link was established between the cytotoxicity of their extracts and total KmTx content. This may reflect differences in potency among KmTx analogs, although the involvement of other uncharacterized compounds cannot be excluded
Evidence of vertical stratification in marine environments: insights from passive acoustic monitoring in French Polynesia
No full textInternational audienceThe stratification of species distribution in marine environments is well-documented, reflecting the influence of depth-related factors such as light availability, temperature, pressure, and habitat structure on the organization of marine communities. This study aimed to determine whether this stratification can also be highlighted using Passive Acoustic Monitoring (PAM), a technique proven effective in the study of various marine habitats. Sounds were recorded at 300 m in July 2022 off Moorea Island (French Polynesia) using a SNAP acoustic recorder. These data were compared to both those collected at shallower depths at Moorea Island (20, 60, and 120 m) and to data from other Polynesian islands obtained during a previous, non-concurrent study. Fish sounds in the recordings were manually identified. Richness and abundance of sounds from 20 m to 300 m depth were compared to assess whether fish communities in the altiphotic reef, upper mesophotic reef, lower mesophotic reef, and rariphotic zone could be distinguished based on the sounds they produce. Comparisons between zones over a 24-h period revealed for the first time the existence of acoustic stratification, with a fourfold decrease in species richness, from the altiphotic reef to the rariphotic zone, along with a general decline in sound abundance. However, this general pattern was not uniform in terms of abundance throughout the day, as sound abundance increased with depth at dusk from 950 sounds per hour at 20 m to 3600 at 300 m. It further confirms that diel activity patterns were also evident in light-deprived zones. This first exploration of vertical acoustic stratification based on fish sounds highlights the undeniable contribution of PAM to studies on the ecology of deep-sea communities
Corrosion Inhibition of C38 Steel in 1 M HCl Using Benzoxazole-2-Thione: Electrochemical, SEM-EDX, and Theoretical Studies
No full textInternational audienceThis study explores the corrosion inhibition of C38 steel in a 1 M hydrochloric acid (HCl) solution using a novel benzoxazole-2-thione compound. The inhibitor was synthesized and structurally characterized by both 1H NMR (DMSO-d6/TMS) and 13C NMR spectroscopy. Electrochemical techniques, including Tafel polarization and electrochemical impedance spectroscopy, were employed to evaluate the inhibition performance. The results indicate that the benzoxazole-2-thione significantly reduces the corrosion rate, achieving a maximum inhibition efficiency of 95.25% at a concentration of 10−4 M. To gain deeper insights into the inhibition mechanism, theoretical methods such as density functional theory, Monte Carlo simulations, and molecular dynamics were applied to investigate the adsorption behavior of the compound on the steel surface. The adsorption process follows the Langmuir isotherm model, suggesting the coexistence of physisorption and chemisorption interactions. Surface morphology and elemental composition analyses using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) confirm the formation of a protective inhibitor film on the steel surface
Scorpions des forêts de nuages : une nouvelle espèce de Guyanochactas Lourenço, 1998(Scorpiones, Chactidae) du Mont Itoupé en Guyane Française
No full textInternational audienceA new species of scorpion belonging to the genus Guyanochactas Lourenço, 1998 (family Chactidae Pocock, 1893), is described on the basis of one specimen collected in the cloud forest of Mount Itoupé, the second highest peak of French Guiana. Guyanochactas itoupe sp. n. represents the fourth species of the genus reported from French Guiana and the total number of Guyanochactas species is now raised to six. The new species is a possible vicariant of Guyanochactas touroulti Lourenço, 2018, equally described from a massif formation of French Guiana, the Mitaraka.Une nouvelle espèce appartenant au genre Guyanochactas Lourenço, 1998 (Chactidae Pocock, 1893), est décrite sur la base d’un spécimen collecté sur le Mont Itoupé, le second plus grand sommet de Guyane Française. Guyanochactas itoupe sp. n. représente la quatrième espèce de Guyanochactas décrite pour la Guyane, et le nombre total d’espèces appartenant à ce genre est porté à six. La nouvelle espèce est un possible vicariant géographique de Guyanochactas touroulti Lourenço, 2018, également décrit d’un massif guyanais, le Mitaraka
