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Resultados 191-200 de 567
A new set of N isotopic reference values for monitoring Ulva green tides in coral reef ecosystems
2024
Van Wynsberge, Simon | Antypas, Florence | Brisset, Maele | Desnues, Anne | Jamet, Léocadie | Lagourgue, Laura | Payri, Claude | Jauffrais, Thierry | Lemonnier, Hugues
Green tides occurrence has increased in coral reefs, yet few reference values have been documented to support bloom management in these ecosystems. Here, we took advantage of recent Ulva green tides that occurred in New Caledonia to (i) identify the elements limiting the growth of Ulva spp. during these blooms; and (ii) validate the use of isotopic markers for identifying sources of nutrients that generated blooms. N/P ratios highlighted a stronger limitation of algae by phosphorus than by nitrogen on sites under oceanic influence, while the proportions of N and P were optimal for algal growth at sites where green tides occurred. Macroalgae highly exposed to sewage water was characterized by higher δ15N than macroalgae collected in areas exposed to synthetic inorganic fertilizers. From these results, we established a new set of threshold values for using δ15N in Ulva species as an indicator of nitrogen source type in coral reefs.
Mostrar más [+] Menos [-]Comparative analysis of microplastics detection methods applied to marine sediments: A case study in the Bay of Marseille
2024
Gerigny, Olivia | Blanco, Gustavo | Lips, Urmas | Buhhalko, Natalja | Chouteau, Leelou | Georges, Elise | Meyers, Nelle | Vanavermaete, David | Galgani, Francois | Ourgaud, Melanie | Papillon, Laure | Sempéré, Richard | De Witte, Bavo
An intercomparison exercise on “microplastics in sediment” was carried out by five laboratories using samples collected in the Bay of Marseille in September 2021. The results from different extraction and identification methods varied depending on the type and size classes of MPs, and was better than 80 % for the size class >300 μm and for the fragments. The variability in recovery rates can be attributed to the choice of reagents and extraction protocols. Recovery rates per laboratory were between 47 % and 113 % and the use of ZnCl2 and NaI increased recovery rates by an average of 70 %. The lowest recovery rates (47 and 53 %) were attributed to the reference methods (FTIR and LDIR), conversely the highest (80 and 87 %) were attributed to identification by Nile Red. The average ranged between 23 and 53 items /50 g d.w. with decreases offshore and at greater depth.
Mostrar más [+] Menos [-]Active mussel biomonitoring for the health status assessment of the Western Mediterranean Sea
2024
Benito, Denis | Briand, Marine | Herlory, Olivier | Izagirre, Urtzi | Bouchoucha, Marc | Briaudeau, Tifanie
The Western Mediterranean coast is under the influence of anthropogenic pressures, including land use, increasing amounts of dangerous waste and habitat destruction. In 2021, the French RINBIO network (http://www.ifremer.fr/envlit/) originally dedicated to assess chemical contamination in the region, focused on biological effects produced by contaminants and the interaction with natural variability in mussels using an active caging strategy. Cell and tissue level biomarkers were applied for 17 sampling sites divided in three sub-regions categorized by different environmental conditions. Results provide critical information for ecosystem health assessment using mussels as sentinel species in the Western Mediterranean Sea. The influence of natural and confounding factors (trophic condition, reproductive cycle, caging strategy), on biological responses to mild chemical contamination, was discussed and discriminated for health status assessment. Results provide valuable data available as reference values for the assessment of biomarkers and histopathological alterations for large-scale active biomonitoring campaigns in the Western Mediterranean Sea.
Mostrar más [+] Menos [-]The French Mussel Watch Program reveals the attenuation of coastal lead contamination over four decades
2024
Barreira, João | Ferreira Araujo, Daniel | Knoery, Joël | Briant, Nicolas | Machado, Wilson | Grouhel, Anne
The mid-20th century industrial peak caused severe global lead (Pb) marine contamination. Although Europe initiated Pb emission reduction regulations in the 1980s, the short- and long-term impacts remain unclear. This study investigates the evolution of Pb contamination on the French coast through elemental and isotope analysis in oysters and mussels from the French “Mussel Watch” Program. Observations at 114 monitoring stations over four decades have shown decreasing Pb levels in these bivalve mollusks. In 1988, 95 % exceeded the background reference values; this level had dropped to 39 % by 2021. The Pb isotope ratios in bivalves from eight target sites revealed a reduction in bioaccumulated anthropogenic Pb, albeit without complete elimination. The long residence time of legacy Pb combined with inputs from diffuse urban sources likely explains the persistent presence of anthropogenic Pb on the French coast. This study endorses the importance of continuous biomonitoring to evaluate environmental regulations and policies.
Mostrar más [+] Menos [-]Persistent organic pollutants and trace metals in selected marine organisms from the Akanda National Park, Gabon (Central Africa)
2024
Sardenne, Fany | Le Loch, Francois | Bodin, Nathalie | Mve-beh, Jean-hervé | Munaron, Jean-marie | Mbega, Jean-daniel | Nzigou, Aime Roger | Sadio, Oumar | Budzinski, Hélène | Leboulanger, Christophe
Akanda National Park (ANP) is composed of mangrove ecosystems bordering Libreville, Gabon's capital. The contamination of aquatic resources from the ANP by persistent organic pollutants (POPs) and trace metals (TMs) was never evaluated. To provide a basis for their monitoring in the ANP, five species (two fish, two mollusks, and one crustacean) were analyzed from three sampling sites in 2017. Contamination levels for POPs and TMs were below maximum acceptable limits for seafood, including Cd and Pb. No DDT was found in any sample. Inter-specific differences were more obvious than the differences among sites, although the results may be biased by an unbalanced sampling design. The oyster Crassostrea gasar was the most contaminated species, making this species a good candidate to assess environmental contamination in the area. The studied species also contained essential elements, such as Fe, Zn and Mn at interesting levels in a nutritional point of view.
Mostrar más [+] Menos [-]Mismanaged plastic waste and the environmental Kuznets curve: A quantile regression analysis
2024
Rom, Punloeuvivorth | Guillotreau, Patrice
The relationship between economic growth, governance, and environmental outcomes, particularly mismanaged plastic waste (MPW) leaking out to the ocean, has been a focal point of policy and academic debates. This study aims to understand the dynamics of income and control of corruption across different levels of MPW. Utilizing Quantile Regression models, we explore the generalized and quantile-specific relationships between the variables. The findings confirm the validity of the Environmental Kuznets Curve (EKC), revealing an initial increase in MPW with economic growth, followed by a decline after surpassing a specific economic threshold. However, the EKC is not validated for all quantiles and the shifting point may vary across the distribution. Moreover, control of corruption emerged as a significant factor in determining MPW levels, emphasizing its moderating role at the highest levels of mismanagement. This study underscores the need for synergizing economic strategies with robust environmental policies, guided by strong governance mechanisms.
Mostrar más [+] Menos [-]Relevance of flounder caging and proteomics to explore the impact of a major industrial accident caused by fire on the Seine estuarine water quality
2024
Laurent, Jennifer | Diop, Mamadou | Amara, Rachid | Fisson, Cédric | Armengaud, Jean | Labadie, Pierre | Budzinski, Hélène | Couteau, Jérôme | Maillet, Géraldine | Le Floch, Stephane | Laroche, Jean | Pichereau, Vianney
On September 26th 2019, a major fire occurred in the Lubrizol factory located near the Seine estuary, in Rouen-France. Juvenile flounders were captured in the Canche estuary (a reference system) and caged one month in the Canche and in the Seine downstream the accident site. No significant increases of PAHs, PCBs and PFAS was detected in Seine vs Canche sediments after the accident, but a significant increase of dioxins and furans was observed in water and sewage sludge in the Rouen wastewater treatment plant. The proteomics approach highlighted a dysregulation of proteins associated with cholesterol synthesis and lipid metabolism, in fish caged in the Seine. The overall results suggested that the fire produced air borne dioxins and furans that got deposited on soil and subsequently entered in the Seine estuarine waters via runoff; thus contaminating fish preys and caged flounders in the Seine estuary.
Mostrar más [+] Menos [-]Operationalizing blue carbon principles in France: Methodological developments for Posidonia oceanica seagrass meadows and institutionalization
2024
Comte, Adrien | Barreyre, Jeanne | Monnier, Briac | De Rafael, Roman | Boudouresque, Charles-françois | Pergent, Gérard | Ruitton, Sandrine
Conservation of ecosystems is an important tool for climate change mitigation. Seagrasses, mangroves, saltmarshes and other marine ecosystems have particularly high capacities to sequester and store organic carbon (blue carbon), and are being impacted by human activities. Calls have been made to mainstream blue carbon into policies, including carbon markets. Building on the scientific literature and the French voluntary carbon standard, the ‘Label Bas-Carbone’, we develop the first method for the conservation of Posidonia oceanica seagrasses using carbon finance. This methodology assesses the emission reduction potential of projects that reduce physical impacts from boating and anchoring. We show how this methodology was institutionalized thanks to a tiered approach on key parameters including carbon stocks, degradation rates, and decomposition rates. We discuss future needs regarding (i) how to strengthen the robustness of the method, and (ii) the expansion of the method to restoration of seagrasses and to other blue carbon ecosystems.
Mostrar más [+] Menos [-]Sediment grain size and benthic community structure in the eastern English Channel: Species-dependent responses and environmental influence
2024
Chauvel, Nathan | Raoux, Aurore | Weill, Pierre | Dezilleau, Laurent | Méar, Yann | Murat, Anne | Poizot, Emmanuel | Foveau, Aurélie | Desroy, Nicolas | Thiébaut, Éric | Dauvin, Jean-claude | Pezy, Jean-philippe
This study addresses the scarcity of evidence on the relationship between benthic communities and coarse-grained sediments in the eastern English Channel. The region's geological history contributes to its predominantly coarse sediment composition. The study employs ternary plots to visualize benthic species' preferences and tolerance for sediment types, revealing their effectiveness. Redundancy Analyses (RDA) and species-level quantile regressions explore the influence of grain size on benthic species distribution. The results indicate a moderate impact of grain size, influenced by hydrodynamics. Estuaries, particularly the Seine Estuary, significantly shape benthic species distribution. Quantile regressions underscore the varied responses of benthic communities along the grain size gradient. The study underscores the importance of considering coarse sediments, offering insights into the complex relationship between benthic communities and sediment characteristics.
Mostrar más [+] Menos [-]Estimation of the introduction risk of non-indigenous species through ship ballast water in the Port of Douala (Cameroon)
2024
Nfongmo Nkouefuth, Yannick | Mamert Onana, Fils | Masseret, Estelle | Nana, Paul Alain | Ewoukem, Thomas Efole | Kacimi, Adel
The transport of non-indigenous species in ship's ballast water represents a threat to marine biodiversity. This study is the first on marine bioinvasion in Sub-Saharan Africa. The Port of Douala (PoD), located in the Gulf of Guinea, is experiencing increasing maritime traffic, hence the importance of preventing biological invasions. PoD received ballast water from 41 ports and 20 ecoregions during the study period (2018–2021). We used a biological invasion model and showed that ships from the ports of Antwerp, Durban, Dar es Salaam, Pointe-Noire (Southern Gulf of Guinea) and Dakar (Sahelian Upwelling), with their associated ecoregions present a major invasion risk. Treating ballast water from these ships to IMO D-2 standards could reduce their probability of biological invasion by 97.18, 98.43, 98.80, 98.77 and 98.84 %, respectively. Climate change may also mitigate the risk of biological invasion, particularly for ships in the North Sea ecoregion from the port of Antwerp.
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