Kinetics of metal and metalloid concentrations in holopelagic Sargassum reaching coastal environments
Since 2011, the Caribbean Islands have experienced unprecedented stranding of a pelagic brown macroalgae Sargassum inducing damages for coastal ecosystems and economy. This study measures the kinetics of metal trace elements (MTE) in Sargassum reaching different coastal environments. In July 2021, over a period of 25 days, fixed experimental floating cages containing the three Sargassum morphotypes (S. fluitans III and S. natans I and VIII) were placed in three different coastal habitats (coral reef, seagrass, and mangrove) in Guadeloupe (French West Indies). Evolution of biomasses and their total phenolic content of Sargassum reveals that environmental conditions of caging were stressful and end up to the death of algae. Concentrations of 19 metal(loid) trace elements were analyzed and three shapes of kinetics were identified with the MTE that either concentrate, depurate, or remains stable. In the mangrove, evolution of MTE was more rapid than the two other habitats a decrease of the As between 70 and 50 μg g−1 in the mangrove. Sargassum natans I presented a different metal composition than the two other morphotypes, with higher contents of As and Zn. All Sargassum morphotype are rapidly releasing the metal(oid)s arsenic (As) when they arrive in studied coastal habitats. In order to avoid the transfer of As from Sargassum to coastal environments, Sargassum stranding should be avoided and their valorization must take into account their As contents.
(Environmental Science and Pollution Research. vol. 30, n° 0944-1344, pp. 104779-104790, 14/09/2023)
ISYEB, MNHN, EPHE, PSL, SU, CNRS, UA, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, ULaval, INSU - CNRS, CNRS, LEMAR, IRD, IFREMER, UBO EPE, CNRS
Molecular confirmation of pearl formation in arctic mussels (Mytilus edulis) caused by Gymnophallus bursicola (Odhner 1900) metacercariae
Abstract In recent field studies, suspected gymnophallid metacercariae were histologically located in the mantle of mussels from the Norwegian Sea. Mussels from the sites in which that infection was detected also presented abnormally high pearl numbers. It has been previously described that gymnophallid metacercariae could cause pearl formation processes in mussels, as a host reaction to encapsulate these metacercariae. Given the pathological host reaction these parasites elicit, a study was performed to identify gymnophallid metacercariae found in mussels collected from Tromsø at morphological and molecular level and to assess, by the use of molecular tools, the relationship between the parasite and the biological material inside the pearls. As a result, Gymnophallus bursicola metacercariae infecting Norwegian Mytilus edulis were identified according to morphological characters, along with the first 18S rDNA and COI sequences for this trematode species. In addition, parasite DNA from the core of the pearls was extracted and amplified for the first time, confirming the parasitological origin of these pearls. This procedure could allow identifying different parasitic organisms responsible for the generation of pearls in bivalves.
(Parasitology, n° 0031-1820, pp. 1-7, 14/09/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Modéliser les risques d’émissions de gaz à effet de serre dues aux feux de forêt
(13/09/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, Bordeaux Sciences Agro
Contrasting vegetation response during Heinrich events 4, 5 and 6 in Western Europe
Deep-sea and terrestrial records allow to document the amplitude, timing and duration of the oceanic and vegetation responses to orbital and millennial-scale changes, in particular during North Atlantic cooling events (Heinrich events, HEs) in Western Europe during the Last Glacial Period (~115- 27 ka). We propose a multiproxy study based on two deep-sea cores retrieved in the Bay of Biscay (MD04-2845) and the Gulf of Lion (MD99-2343) to reconstruct vegetation and climatic changes in southwestern and southeastern France during Heinrich stadials 4, 5 and 6. These records are well chronologically constrained by numerical dating (new IRSL ages for the MD04-2845 deep-sea core) and new age-depth models, based on Bayesian statistics and stratigraphic constrains using ChronoModel software and ArchaeoPhases R-package. The comparison of both deep-sea cores with other terrestrial and marine records from NE Atlantic and NW Mediterranean regions show different magnitudes in the semi-desert expansions following Heinrich Stadials (HS, 4, 5 and 6) in Western Europe. Although in southwestern France, the development of the semi-desert is more pronounced during HS6 compared to HS 4 and 5, in the southeast, this stadial is marked by forest development. These contrasted responses during these events appear to be the result of different intensities of the thermohaline circulation and local oceanic processes associated with the instability of the Laurentian ice sheet.
(13/09/2023)
UB, UBM, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, EPHE, PSL, LCE, CNRS, UFC, UBFC, UQAT, LMJL, CNRS, Nantes univ - UFR ST, Nantes Univ
Organic Matter Dynamics in a Human-Impacted Estuary: Insights from Biomarkers and Excitation-Emission Matrix Fluorescence
(pp. 1-2, 10/09/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Benthic community impacts from sediment dredging and disposal: A comparison of sampling gear
The effect of sediment dredging and disposal work on benthic communities was compared according to two sampling strategies, grab (1-mm mesh) and dredge (1-cm mesh). Nine subtidal, sandy sites were selected in Arcachon Bay (French Atlantic coast), where these operations were performed during winter. Fauna was sampled several months before and one year after the dredging or disposal work. The sediments were fine to medium sands and their characteristics were not modified. In dredging sites, abundance, diversity and community structure of grab sampled fauna were minimally affected by the activities, while abundance and community structure displayed significant changes for dredge sampled fauna. In disposal sites, there was no work effect on fauna, although environmental conditions changed, especially when initial sediments were covered by mussels or seagrass. This study suggests that dredge sampling can be an alternative to grab sampling for monitoring changes related to dredging in sandy shallow channels.
(Marine Pollution Bulletin. vol. 194, n° 0025-326X, pp. 115278, 01/09/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Plastic debris, persistent organic pollutants and their toxicity impacts in coastal areas in Central Chile.
The chemical components of plastic wastes have made their disposal a major economic, social, and environmental problem worldwide. This study evaluated the acute toxicity and genotoxicity of marine plastic debris on the beaches of Concepción Bay, Central Chile, taken during three periods (spring, summer, and winter). An integrated approach was used, including chemical and toxicological data, using the Microtox® test with Vibrio fischeri and SOS chromotest with Escherichia coli and concentrations of polychlorinated biphenyls (PCBs), Organochlorine Pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). The results presented here exclusively include the novel data obtained from the winter campaign, revealing high concentrations of PBDEs (238 ± 521 ng g). In addition, the genotoxicity and acute toxicity tests were sensitive for most of the samples studied. This investigation is the first attempt to analyse the toxicity of plastic debris in coastal areas along the Chilean coast.
(Marine Pollution Bulletin. vol. 194, n° 0025-326X, pp. 115361, 01/09/2023)
EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS
Isotopic and biochemical trophic markers reveal the complexity of interactions at the base of pelagic food webs (Mediterranean sea).
To gain insight into the impact of bottom-up changes in the plankton community on planktivorous fish in the context of the decline of small pelagic fisheries in the Northwestern Mediterranean Sea, we have conducted an extensive year-long study. The investigation combined biochemical analyses (proteins, carbohydrates, and lipids) with C and N stable isotope analyses (SIA) to simultaneously study phytoplankton, zooplankton, and eight planktivorous fish species (Engraulis encrasicolus, Sardina pilchardus, Sardinella aurita, Sprattus sprattus, Cepola macrophthalma, Chromis chromis, Boops boops, and Spicara maena). This study is the first to analyze both stable isotope and biochemical compositions in coastal particulate organic matter (POM) size classes (0.7-2.7 μm, 2.7-20 μm, and 20-200 μm), zooplankton size classes (200-300 μm, 300-500 μm, 500-1000 μm, 1000-2000 μm, and >2000 μm), and taxonomic groups. We demonstrated that: (1) POM stable isotope compositions varied based on its spatial origin, the taxonomic composition of its biota, and its biochemical content; (2) δ15N values increased with zooplankton size classes and groups, indicating different trophic levels; (3) Phytoplankton exhibited a lipid-rich composition (∼55%), while zooplankton and fish muscles were protein-rich (∼61% and ∼66%, respectively). Bayesian stable isotope mixing models revealed that, on average: (1) POM from oceanic waters contributed the most to the POM in the bay (>51%), with a dominance of pico-POM (∼43%); (2) The 200-1000 μm zooplankton primarily consumed nano-POM, the 1000-2000 μm zooplankton mostly consumed micro-POM (∼64%), and the >2000 μm zooplankton also mostly consumed micro-POM; (3) Mesozooplankton (200-2000 μm) constituted the main portion (∼42%) of the diet for planktivorous fish species, while macrozooplankton organisms (>2000 μm) were the primary food resource (∼43%) for both B. boops and S. sprattus. Our study underscores the complexity of the pelagic food web and highlights the bottom-up transfer of organic matter from the smallest phytoplankton size fractions to planktivorous fish.
(Marine Environmental Research. vol. 190, n° 0141-1136, pp. 106123, 01/09/2023)
MIO, IRD, AMU, INSU - CNRS, UTLN, CNRS, ENTROPIE [Nouvelle-Calédonie], IRD [Nouvelle-Calédonie], IFREMER, UNC, CNRS, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, LIENSs, INSU - CNRS, ULR, CNRS, ULR
Altered ovarian transcriptome is linked to early mortality and abnormalities in zebrafish embryos after maternal exposure to gamma irradiation
Recent laboratory studies focusing on multigenerational approach demonstrated drastic phenotypic effects after chronic fish irradiation exposure. No irradiation effect at phenotypic scale was observed for F0 (reproductive performances) while early mortality and malformations were observed in F1 offspring whether they were irradiated or not. The objective was to study molecular mechanisms likely to be involved in these phenotypic effects induced by parental irradiation. Thus, F0 adult zebrafish were irradiated for ten days until reproduction and maternal involvement in offspring development was assessed. Levels of maternal provided cortisol and vitellogenin, needed for embryo development, were not impacted by irradiation. However, maternal transcriptome highlighted irradiation effect on processes involved in oocyte development, as well as on essential maternal factors needed for offspring development. Therefore, this study highlighted the importance of parental exposure on offspring fate and of the importance of multigenerational exposure in risk assessment.
(Aquatic Toxicology. vol. 262, n° 0166-445X, pp. 106660, 01/09/2023)
IRSN/PSE-ENV/SRTE/LECO, IRSN/PSE-ENV/SRTE, IRSN, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS, UMR MARBEC, IRD, IFREMER, CNRS, UM
Interpolation spatiale avec un réseau de neurones génératif comme alternative au krigeage
En géosciences, les méthodes d'interpolation spatiale peuvent être divisées en géostatistiques, non-géostatistiques ou hybrides. Le krigeage est une méthode couramment utilisée en géostatistique, sous l'hypothèse d'une distribution normale des données. De plus, il peut être très gourmand en ressources lorsqu'il est utilisé pour réaliser une interpolation avec un volume de données conséquent. Les méthodes non-géostatistiques ont bénéficié des avancées récentes des Réseaux Antagonistes Génératifs (GAN), mais elles exigent une quantité importante de données étiquetées pour produire des résultats performants. Les approches hybrides sont limitées de part leurs dépendances aux contraintes associées aux approches géostatistiques. Dans cet article, nous proposons une nouvelle méthode d'interpolation spatiale non-géostatistique par apprentissage profond, en se basant sur une technique de reconstruction d'image sans entraînement au préalable, permettant ainsi de surmonter les limites des GAN. Notre méthode utilise des connexions résiduelles et un sur-échantillonnage bi-cubique dans le but d'adapter la technique de reconstruction d'image à notre application. Elle s'appuie sur un réseau de neurones convolutifs pour produire une carte à partir d'une carte de valeurs aléatoires, en réduisant la différence entre la carte générée et les valeurs observées. L'approche proposée est évaluée sur un jeu de données de modèle numérique de terrain selon deux méthodes d'échantillonnage différentes : régulière et aléatoire. Les résultats montrent des performances supérieures par rapport à l'état de l'art des méthodes l'interpolation.
(28/08/2023)
LITIS - App, LITIS, ULH, NU, UNIROUEN, NU, INSA Rouen Normandie, INSA, NU, EPOC, EPHE, PSL, UB, INSU - CNRS, CNRS