Organic Pollutants in Coastal Waters, Sediments, and Biota: A Relevant Driver for Ecosystems During the Anthropocene?

The total number of synthetic organic chemicals introduced to the environment by humans has never been quantified, but it is not lower than thousands. A fraction of these chemicals have toxic effects to coastal organisms and presumably affect ecosystems structure and function. During the last decades, some of the processes affecting the transport, degradation, and fate of a limited number of chemicals have been studied, and the rising concern for environmental risk of organic chemical has lead to the regulation of a few of them by national and international organisms. However, the environmental inventory of organic pollutants is far from being quantified, and current methodologies used in most toxicological tests only allow to determine effects of individual chemicals to organisms. There are major limitations on appropriate methodologies to assess the effects of organic pollutants at population and ecosystem levels and the effects induced by complex mixtures of organic pollutants present in natural environments. The modification of the composition of the biosphere by a myriad of organic pollutants at ultra-trace levels is not yet regarded as another vector of environmental change which is irreversible due to the persistent character of many of these chemicals and due to its global coverage. Here, we claim that the modification of the atmosphere, water, sediments, and biota composition is a factor to be taken into account in coastal ecosystems, and that its pressure on the environment has been exponentially increasing during the last six decades of the anthropocene.Peer reviewe

Lipid biomarker record in surface sediments at three sites of contrasting productivity in the tropical North Eastern Atlantic

International audienceSelected lipid biomarkers were analyzed in modern aerobic surface sediments from the tropical NE Atlantic off the Mauritanian coast, in the frame of the JGOFS EUMELI program. This paper explores how sedimentary molecular proxies record productivity and vascular plant inputs. Dry weight-normalized concentrations and TOC-normalized concentrations of biomarkers poorly matched the gradient of higher-plant inputs and of primary productivity. In contrast, mass accumulation rates of long-chain n-alkanols and n-fatty acids (80-710 and 210-1750 μg m- 2 yr- 1, respectively) showed good agreement with dust inputs transported between 15 and 24°N by NE trade winds, whereas long-chain n-alkanes showed a distinct pattern. At the coastal site, n-alkanols and n-fatty acids predominated over long-chain n-alkanes. Cross-shelf changes in proportions of n-fatty acids and n-alkanols relative to n-alkanes point to an increased degradation of terrigeneous waxes when going offshore. The cross-shelf C/N ratio poorly registered vascular plant inputs, most probably because denitrification influenced C/N values at the eutrophic site. Mass accumulation rates of phytoplanktonic biomarkers declined from the eutrophic to the oligotrophic site, reflecting the primary productivity variation. Mass accumulation rates of highly branched isoprenoid hydrocarbons, C37 n-alkenones, n-alkyl diols and dinosterol varied from 3 to 410, 9 to 1600, 12 to 360 and 7 to 320 μg m- 2 yr- 1, respectively. They target the productivity of Haslea-type diatoms, coccolithophorids, eustigmatophytes and dinoflagellates. While the results encourage the development of molecular proxies of palaeoproductivity and of palaeophytocommunities, progress is still needed to deconvolute the impact of degradation on mass accumulation rates and to move towards quantitative calibrations

Aliphatic hydrocarbons and triterpenes of the Congo deep-sea fan

International audienceHydrocarbons were analyzed in sediments from the Congo River deep-sea fan, from the Congo River, and in sinking particles collected by sediment traps 40 m above the sediment. Studied sites encompassed three lobes of decreasing age of formation along the canyon: sites A, F and C and a another lobe system, disconnected from the active channel since 4 ka, Site E. Terrestrial long-chain odd n-alkanes were dominant in all sediments of the lobe system. Unsaturated terpenoids sourced by higher plants, such as gammacerene, lupene, ursene and oleanene, were also detected. At site C, characterized by high accumulation rates (10–20 cm yr−1), the organic matter spends less time in the oxic layer than at other sites and high phytadiene concentrations 10–17 μg gOC−1) evidenced recent terrestrial and phytoplanktonic remains reworked in anaerobic conditions. In these sediments, organic carbon-normalized concentrations of terrestrial alkanes and terpenoids were several fold higher than in the lobe sediments with lower accumulation rates (sites A and F), arguing for a more rapid degradation of terrestrial hydrocarbons than bulk organic carbon in the first steps of pre-diagenesis. Ample variations in the contributions of biomarkers from higher plants, ferns, bacteria and angiosperms, indicate an heterogeneous contribution of the soil and vegetation detritus delivered to the Congo lobe sediments. Lower concentrations in terrestrial hydrocarbons at site E, 45 km away from the active canyon, indicated that river particles are still admixed to the dominant marine organic matter. Diploptene and hop-7(21)-ene have a dual origin, from terrestrial and marine microorganisms. Scatter in their relationship to gammacerene argues for a contribution of marine microorganisms, in addition to soils-sourced microorganisms. The close distribution patterns of diploptene, hop-21-ene, hop-7(21)ene and neohop-13(18)-ene is in line with the hypothesis of sequential clay-catalyzed isomerisation of bacterial hopenes. Terrestrial biomarker accumulation fluxes at site C are one order of magnitude higher than vertical pelagic flux, demonstrating the magnitude of the inputs delivered through turbiditic transport in the submarine canyon. Crude oil contamination was evidenced at the disconnected site E (UCM, C21 to C26 tricyclic diterpanes, CPI) and, in smaller amounts, in some sediments from sites A and C. It may be related to marine crude oil extraction and transport. A short-chain mode of alkanes with an even predominance is evidenced in sediments of the lobe complex and likely sources, crude oil, microorganisms and ferns, are discussed

Long chain n-alkyl diols, hydroxy ketones and sterols in a marine eustigmatophyte, Nannochloropsis gaditana, and in Brachionus plicatilis feeding on the algae

12 pages, 6 figures, 4 tables.-- Printed version published Apr 2003.Base-hydrolyzed sterols and long-chain alcohols of a marine eustigmatophyte, Nannochloropsis gaditana have been studied. Sterol composition of N. gaditana is similar to that of other member of this genus, with predominance of cholest-5-en-3β-ol and 24-ethylcholest-5-en-3β-ol. The C29:2 and C30:1 unsaturated aliphatic alcohols were predominant. Saturated and monounsaturated C28 to C36 n-alkyl diols occurred as a mixture of positional isomers with ω16 predominating among the C28 alkyl diols, ω18 among C30, C32, C34 and C36 alkyl diols and ω17 for the odd chain alkyl diols. C28–C32 hydroxy ketones were identified for the first time in a marine organism, with a distribution parallelling the alkyl diol mixtures and suggesting a biosynthetic relation between both alcohol classes. N. gaditana was fed to Brachionus plicatilis and the distribution of alkyl diol positional isomers remained the same in the algae and the rotifer fecal pellets. However, digestion resulted in an increase in C30 diols relative to C32 diols and in an enrichment of unsaturated long-chain alcohols relative to alkyl diols.Peer reviewe

Ergosterol biosynthesis in novel melanized fungi from hypersaline environments

8 pages, 3 figures, 1 table.-- PMID: 11254746 [PubMed].Halotolerant and halophilic melanized fungi were recently described in hypersaline waters. A close study of the sterol composition of such fungi, namely Hortaea werneckii, Alternaria alternata, Cladosporium sphaerospermum, Cladosporium sp., and Aureobasidium pullulans revealed the dominance of ergosterol and the presence of 29 intermediates of its biosynthesis pathway. The presence or absence of intermediates from distinct synthesis routes gave insight into the operative synthetic pathways from 4,4,14-trimethylcholesta-8,24-dien-3 beta-ol (lanosterol) to ergosterol in melanized fungi and in Saccharomyces cerevisiae, a reference yeast cultured in parallel. In all studied melanized fungi, initial methylation at C-24 took place before C-14 and C-4 demethylation, involving a different reaction sequence from that observed in S. cerevisiae. Further transformation was observed to occur through various routes. In A. alternata, isomerization at C-7 takes place prior to desaturation at C-5 and C-22, and methylene reduction at C-24. In addition to these pathways in Cladosporium spp., H. werneckii, and A. pullulans, ergosterol may also be synthesized through reduction of the C-24 methylene group before desaturation at C-5 and C-22 or vice versa. Moreover, in all studied melanized fungi except A. alternata, ergosterol biosynthesis may also proceed through C-24 methylene reduction prior to C-4 demethylation.Financial support from the European Union (MAST Project MAS3-CT98-5057) is acknowledged. This project has also been funded by Comision Interdepartamental de Ciencia y Tecnologia (PB93-0190-C02-01) from the Spanish Ministry of Education.Peer reviewe

Water-sediment partitioning of flumequine and florfenicol, two antibiotics used in salmon aquaculture in Chile

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Salt-induced changes in lipid composition and membrane fluidity of halophilic yeast-like melanized fungi

9 pages, 5 figures, 1 table.-- PMID: 15064990 [PubMed].-- Available online Nov 3, 2003.The halophilic melanized yeast-like fungi Hortaea werneckii, Phaeotheca triangularis, and the halotolerant Aureobasidium pullulans, isolated from salterns as their natural environment, were grown at different NaCl concentrations and their membrane lipid composition and fluidity were examined. Among sterols, besides ergosterol, which was the predominant one, 23 additional sterols were identified. Their total content did not change consistently or significantly in response to raised NaCl concentrations in studied melanized fungi. The major phospholipid classes were phosphatidylcholine and phosphatidylethanolamine, followed by anionic phospholipids. The most abundant fatty acids in phospholipids contained C16 and C18 chain lengths with a high percentage of C18:2Delta9,12. Salt stress caused an increase in the fatty acid unsaturation in the halophilic H. werneckii and halotolerant A. pullulans but a slight decrease in halophilic P. triangularis. All the halophilic fungi maintained their sterol-to-phospholipid ratio at a significantly lower level than did the salt-sensitive Saccharomyces cerevisiae and halotolerant A. pullulans. Electron paramagnetic resonance (EPR) spectroscopy measurements showed that the membranes of all halophilic fungi were more fluid than those of the halotolerant A. pullulans and salt-sensitive S. cerevisiae, which is in good agreement with the lipid composition observed in this study.M. Turk was supported by a fellowship from the Slovene Ministry of Education, Science and Sport.Peer reviewe

Distribution of polycyclic aromatic hydrocarbons (PAHs) in sewage effluent, continental and coastal waters from the Northwestern Mediterranean Sea: Comparison between two contrasted catchment areas (Marseilles Bay and Vermeille coast)

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