Papers by Madeleine Goutx
Environmental Science and Pollution Research, 2015
We evaluated the relative impact of anthropogenic polycyclic aromatic hydrocarbons (PAHs) among b... more We evaluated the relative impact of anthropogenic polycyclic aromatic hydrocarbons (PAHs) among biogeochemical variables on total, metabolically active, and PAH bacterial communities in summer and winter in surface microlayer (SML) and subsurface seawaters (SSW) across short transects along the NW Mediterranean coast from three harbors, one wastewater effluent, and one nearshore observatory reference site. At both seasons, significant correlations were found between dissolved total PAH concentrations and PAH-degrading bacteria that formed a gradient from the shore to nearshore waters. Accumulation of PAH degraders was particularly high in the SML, where PAHs accumulated. Harbors and wastewater outfalls influenced drastically and in a different way the total and active bacterial community structure, but they only impacted the communities from the nearshore zone (<2 km from the shore). By using direct multivariate statistical analysis, we confirmed the significant effect of PAH concentrations on the spatial and temporal dynamic of total and active communities in this area, but this effect was putted in perspective by the importance of other biogeochemical variables.
Biogeosciences Discussions, 2010
Interactions between carbon and silica in the diatom frustule play an important role in carbon ex... more Interactions between carbon and silica in the diatom frustule play an important role in carbon export through their impact on diatom remineralization (carbon degradation and biogenic silica dissolution). To ameliorate model prediction of the fate of Si and organic matter during sedimentation, there is a need to first understand the origin and nature of Si-OC interactions, their impact on diatom
Anthropogenic production of greenhouse effect gases has led atmospheric CO2 partial pressure to r... more Anthropogenic production of greenhouse effect gases has led atmospheric CO2 partial pressure to raise from 280 to 360 µatm between 1880 and 1990. It will probably reach 700 µatm by 2100. The aim of the DOREMI project was to investigate the possible influence of increased CO2 partial pressure on marine microplankton communities. As a part of this project, the microalgae Emiliana Huxleyi was cultured in vitro under controlled pCO2 (360 µatm and 720 µatm) and subsequently submitted to a biodegradation experiment. Evolution of lipid composition and microbial enzymatic degradation, determined over a 20 day period, will be presented and discussed.
Three hydrocarbon uptake modes (adherence, emulsi®cation and solubilization) were identi®ed and q... more Three hydrocarbon uptake modes (adherence, emulsi®cation and solubilization) were identi®ed and quanti®ed in cells and supernatants of a mesophilic marine bacterium Pseudomonas nautica strain 617 grown on eicosane. The adherence capacity was related to the enrichment of cells with wax esters and glycolipids. The emulsifying activity was related to the presence of extracellular biosurfactants composed of proteins, carbohydrates and lipids (35:63:2). The intensity of substrate uptake modes was sensitive to temperatures currently found in the original environment of P. nautica (16°C, 20°C and 32°C). When temperature decreased, a signi®cant increase in adherence and emulsifying activity was observed in relation to biochemical changes, whereas solubilizing activity decreased. The marine bacterium was able to degrade 53±59% eicosane at the end of exponential growth after 13, 5 and 3 days incubation at 16°C, 20°C and 32°C respectively.
Environmental Pollution, 2014
In the western Mediterranean, the Almeria-Oran front extends at the boundary of the Alboran-Sea. ... more In the western Mediterranean, the Almeria-Oran front extends at the boundary of the Alboran-Sea. At different location through the frontal structure, drifting sediment traps (PPS5) were deployed at 100 m and 300m during a 1-1.5 d sampling period in the December 1997 and January 1998. Simultaneously, samples of dissolved and suspended matter were collected by using CTD/rosette casts from surface
Biogeosciences Discussions, 2009
234Th was used to quantify the short-term variability of particle dynamics and of POC export duri... more 234Th was used to quantify the short-term variability of particle dynamics and of POC export during transition periods in surface waters over the north-western Mediterranean. As a part of DYNAPROC I and II cruises, two intensive time-series of 234Th were carried out near the DYFAMED station (43° 25´N-7°51´E) during late spring (May, 1995), when the system changes towards oligotrophy, and during autumn (October, 2004), when the stratification is disturbed by wind. Particulate fluxes derived from 234Th measured in the upper water column and in drifting sediment trap showed large differences between the two situations: the flux decreased from high to low values during late spring, at the difference of the autumnal situation where the fluxes were always low. 234Th-derived POC fluxes, calculated from the 234Th238U disequilibrium in the water column and POC/234Th ratio on trapped material, and export ratios (ThE: ratio of 234Th-derived POC export to primary production) showed a large range, from 8 to 110 mgC m-2 d-1 and 3-55%; the lowest values were observed at the end of the productive period (end May) and in automn. The 234Th-derived information is in agreement with the annual variations in Mediterranean Sea productivity. From these experiments during transition periods, it is not obvious that renewal of nutrients by wind events is strong enough to sustain significant export after the end of the productive period or to initiate significant export in autumn.
Global Change: Mankind-Marine Environment Interactions, 2010
ABSTRACT High dynamic anthropogenic activities in urban coastal areas are harming the aquatic env... more ABSTRACT High dynamic anthropogenic activities in urban coastal areas are harming the aquatic environment, which may result in partially high contamination levels near urban wastewater discharges and corresponding coastal areas. However, the occurrence, fate, and distribution of numerous anthropogenic contaminants and xenobiotics are still poorly understood. In this chapter, we present strategies and methods focused on lipid biomarkers developed for characterizing and assessing the anthropogenic impact on Marseille’s coastal environment.
Global Change: Mankind-Marine Environment Interactions, 2010
ABSTRACT The Mediterranean Sea coasts are subject to a strong anthropogenic pressure because of a... more ABSTRACT The Mediterranean Sea coasts are subject to a strong anthropogenic pressure because of an intensification of urban, industrial, agricultural, and tourist activities. This anthropogenic pressure is reflected in the direct (from coastal sources) and indirect (via rivers) discharge of terrigenous materials and pollutants. These contributions promote transformations of ecosystems and associated biogeochemical cycles. In order to assess environmental changes, discrete measurements at fixed observation sites are useful, but remain insufficient to describe the synoptic extension and the impact of these released terrigenous inputs. An objective of the laboratory is to develop and use in situ UV fluorometers for the quantification at high spatial and temporal frequency of terrigenous and anthropogenic tracers such as polycyclic aromatic hydrocarbons (PAHs, index of chemical contaminations) and “tryptophan-like” material (rough index of bacterial contaminations). An in situ UV fluorometer (EnviroFlu-HC, TriOS Optical Sensors) was deployed in the coastal area of Marseilles from January to July 2008. The fluorescence signal of this probe (Ex/Em: 254 ± 12.5/360 ± 25 nm) was compared to the spectrofluorimetric excitation emission matrices (EEMs) of discrete samples taken from the same area. The probe signal, due to its relative large excitation and emission bands, covers the EEM signature of several groups of compounds: PAHs, tryptophan-like material, and humic substances. Based on our in situ observations, and in collaboration with a French company specialized in optical sensors, we propose solutions for improving the optical properties of the EnviroFlu-HC fluorometer to better target compounds of interest and miniaturize the probe. Ultimately, these miniaturized UV fluorometers will be integrated to autonomous mobile platforms (gliders). This study is part of a laboratory program that aims to develop observation tools for operational oceanography and urban marine zone management: The project SEA EXPLORER (leader ACSA underwater GPS, partnerships: ACRI-IN, ACRI-ST, IFREMER, LMGEM-COM, LOV) funded by the Ministry of Industry (Fond de Compétitivité des Entreprises, FCE). This work also received the financial support of the Conseil Général des Bouches-du-Rhône (CG 13) and Agence de l’Eau Rhône-Méditerranée.
Lipid class composition of Dunaliella viridis Teodoresco was analysed using thin layer chromatogr... more Lipid class composition of Dunaliella viridis Teodoresco was analysed using thin layer chromatography coupled with flame ionisation detection (TLC/FID technique). D. viridis was cultured under four different photon fluence rates and in darkness, and under two different conditions of CO 2 supply (atmospheric and 1%) with and without nitrogen sufficiency. Nine lipid classes were identified and quantified. Total lipids per cell and acetone-mobile polar lipids decreased with light, while the percentage of sterols and triglycerides increased with increasing irradiance. Total phospholipids increase was related with growth rate while hydrocarbons, wax esters and sterol esters accumulated in darkness. There were almost no changes in total lipids per cell because of nitrogen limitation; however, nitrogen limitation led to higher changes in lipid class composition under 1% CO 2 than under atmospheric CO 2 levels. The main reserve lipid, triglycerides, accumulated in high amounts under 1% CO 2 and nitrogen limitation, increasing from 1% to 22% of total lipids. The ratio sterols/acetone-mobile polar lipids could be an index of the 'light status' independently of nitrogen limitation, while the ratio triglycerides/total phospholipids could indicate any physiological stress uncoupling C and N metabolism and affecting the growth rate.
Biogeosciences Discussions, 2009
Changes in concentration and composition of dissolved lipid classes (Iatroscan TLC/FID) were exam... more Changes in concentration and composition of dissolved lipid classes (Iatroscan TLC/FID) were examined at daily to month scale, in relation to the hydrological and biological situation at a central site of the Ligurian sea, NW Mediterranean during the PECHE-DYNAPROC 2 experiment (14 September to 17 October). Dissolved lipid concen-5 trations (TLd) and lipid to DOC ratios varied in the range 5.3-48.5 µg l −1 and 0.01 to 0.08 respectively, along the 0-1000 m water column. The highest TLd concentration values were found in the 0-150 m surface layer coinciding with phytoplankton biomass. Lipid class composition provided valuable information on the origin of DOM, and the changes that occurred during the period investigated. The significant 10 correlations (p<0.01, n=87) between glycolipids from chloroplast membrane (MGDG) (38.7±8.5% of TLd, n=166), and various phytoplankton pigments (chlorophyll cs-170, violaxanthin, diadinoxanthin, zeaxanthin, and lutein), suggested that picoeucaryotes were the major source of dissolved lipids. Lipid metabolites (37.6±11.1%, n=166), the second most important compounds in TLd, showed a greater degree of degradation 15 of lipids in this transition period than previously observed earlier in the year. A contribution of lipids to DOM in the mesopelagic zone was observed before the winter mixing: At mid time of the cruise (4-6 October), zooplankton wax esters biomarkers (WE, 5.5-13.6 µg L −1 ) appeared in the 0-150 m surface layer. WE were observed later and deeper in the mesopelagic layer (6 to 11 October), accompanied by re-increases 20 of hydrocarbons (6-8 October) and phospholipids concentrations (12 October) in the 400-1000 m depth layer. Zooplankton migration and/or fecal pellets egestion, followed by DOM release from POM, were likely responsible for the appearance of these lipid signatures in the mesopelagic layer, which occurred during the period of low wind (<15 knots) (28 September-12 October). The low salinity water lenses that appeared 25 twice during the cruise in the 40-80 m surface layer had little effect on total biogenic lipid concentrations. Lower concentrations in phosphoglycerides and hydrocarbons than the nearby sea water suggested different microbial assemblages and different 29 BGD
PLoS ONE, 2013
Regeneration of artificially induced lesions was monitored in nubbins of the branching coral Acro... more Regeneration of artificially induced lesions was monitored in nubbins of the branching coral Acropora muricata at two reefflat sites representing contrasting environments at Réunion Island (21u079S, 55u329E). Growth of these injured nubbins was examined in parallel, and compared to controls. Biochemical compositions of the holobiont and the zooxanthellae density were determined at the onset of the experiment, and the photosynthetic efficiency (F v /F m ) of zooxanthellae was monitored during the experiment. Acropora muricata rapidly regenerated small lesions, but regeneration rates significantly differed between sites. At the sheltered site characterized by high temperatures, temperature variations, and irradiance levels, regeneration took 192 days on average. At the exposed site, characterized by steadier temperatures and lower irradiation, nubbins demonstrated fast lesion repair (81 days), slower growth, lower zooxanthellae density, chlorophyll a concentration and lipid content than at the former site. A trade-off between growth and regeneration rates was evident here. High growth rates seem to impair regeneration capacity. We show that environmental conditions conducive to high zooxanthellae densities in corals are related to fast skeletal growth but also to reduced lesion regeneration rates. We hypothesize that a lowered regenerative capacity may be related to limited availability of energetic and cellular resources, consequences of coral holobionts operating at high levels of photosynthesis and associated growth.
Organic Geochemistry, 2002
Large particles (> 60 mm) were collected at 30 and 200 m water depth by in situ pumps in the sout... more Large particles (> 60 mm) were collected at 30 and 200 m water depth by in situ pumps in the southern Indian Ocean in January-February 1999. The samples were incubated under laboratory conditions with their own bacterial assemblages for 7-17 days in batches under oxic conditions in the dark. Particulate and dissolved fractions of organic carbon, amino acids, sugars and lipids, as well as bacterial production were quantified over time. During the experiments, 32-38% and 43-50% of total organic carbon (TOC) was mineralized and considered as labile material in the Polar Front Zone (PFZ) and Sub-Antarctic region (SAr), respectively. This material was utilized with a bacterial growth efficiency (BGE) of 10-21% (PFZ) and 12-17% (SAr), with the lower values being observed for surface samples (30 m). These results imply that most (79-90%) of the incorporated carbon from large particles was respired as CO 2 . The study revealed that the initial relative abundance of the three main classes of organic matter, including sugars, amino acids and lipids, varied greatly between SAr and PFZ, with sugars being more abundant in SAr (15-19% of TOC) than in PFZ (8-9% of TOC). In the PFZ, mineralization rates of amino acids and lipids were two to ten fold higher than those of sugars, whereas the opposite was observed in SAr biodegradation experiments. Moreover, our results suggested that organic carbon is mineralized by bacteria more rapidly in the euphotic zone of the SAr than the PFZ. The differences observed between the two sites may be related to the more rapid dissolution of silica as well as the higher temperatures and bacterial production encountered in SAr waters. The bacterial processes apparently affect the composition of material sinking to the ocean interior. #
Organic Geochemistry, 2004
Sediment cakes, supplemented with microalgal cells (Nannochloropsis salina), were incubated for 3... more Sediment cakes, supplemented with microalgal cells (Nannochloropsis salina), were incubated for 35 days under permanently oxic, oscillating (5d:5d changeover oxic/anoxic) and strictly anoxic conditions of oxygenation in diffusively “open” sedimentary systems. Total lipids (TLip) and triacylglycerols (TG) concentrations were monitored by thin layer chromatography-flame ionisation detection, whereas the concentrations of the main extractable (free+ester-bound) individual fatty acids (C16:0, C16:1, C18:1)
Organic Geochemistry, 1990
ABSTRACT
Organic Geochemistry, 2003
... The biodegradation experiment was conducted during the January–February 1999 Antares 4 cruise... more ... The biodegradation experiment was conducted during the January–February 1999 Antares 4 cruise on board the N/O Marion Dufresne in the ... lipids (0.07–0.11 day −1 , computed from the data given in y −1 ) experimentally determined by [Harvey and Macko, 1997] during algal ...
Microbial Ecology, 2007
Diel and seasonal variations in abundance, activity, and structure of particle-attached vs free-l... more Diel and seasonal variations in abundance, activity, and structure of particle-attached vs free-living bacterial communities were investigated in offshore NW Mediterranean Sea (0-1000 m). Attached bacteria were always less abundant and less diverse but generally more active than free-living bacteria. The most important finding of this study was that the activity of attached bacteria showed pronounced diel variations in the upper mixed water column with higher activities at night. Under mesotrophic conditions, the contribution of attached bacteria to total bacterial activity increased from less than 10% at day time to 83% at night time. At high chlorophyll a concentration, the highest cell-specific activities and contribution to total bacterial activity were due to free-living bacteria at day and to attached bacteria at night. Under summer oligotrophic conditions, free-living bacteria dominated and contributed to the most important part of the bacterial activity at both day and night, whereas attached bacteria were much less abundant but presented the highest cell-specific activities. These diel and seasonal variations in activities were concomitant to changes in bacterial community structure, mainly in the upper layer. The number of attached ribotypes was fairly constant suggesting that particles are colonized by a relatively limited number of ubiquitous ribotypes. Most of these ribotypes were also free-living ribotypes suggest-ing that attached bacteria probably originate from colonization of newly formed particles by free-living bacteria in the upper layer. These results reinforce the biogeochemical role of attached bacteria in the cycling of particulate organic carbon in the NW Mediterranean Sea and the importance of diel variability in these processes.
Lipids, 2009
With the aim of obtaining a better understanding of lipids-lipases interactions in bacterioplankt... more With the aim of obtaining a better understanding of lipids-lipases interactions in bacterioplankton communities in oceans, we used different methods for measuring lipase activities in pure cultures of the marine strain Alteromonas macleodii. The decay of tripalmitate added to cultures was followed chemically over time. In an enzymatic approach, lipase activities were measured using the fluorogenic lipid analogs MUF-palmitate and ELF-palmitate. When hydrolyzed by lipase, the non-fluorescent substrates release MUF and ELF Alcohol (ELFA) which are fluorescent. As shown by spectrofluorometry, ELF-palmitate was an efficient competitor for MUF-palmitate. However, the activities reached using these two fluorogenic substrates were different, but still much higher than the tripalmitate hydrolysis rate, measured chemically. MUF- and ELF-palmitate would not be hydrolyzed by lipase sensu stricto (defined as triacylglycerol acylesterase E.C. 3.1.1.3) but rather reflects lipolytic activities in a broad sense. ELFA is also water-insoluble and theoretically precipitates in the external membrane of bacteria causing its hydrolysis, which would allow microscopic identification of active cells. By epifluorescence microscopy, the accumulation of ELFA fluorescence over time was detected (as large, diffuse halos), but no precipitates were clearly associated with bacteria on slide preparations, neither for pure cultures of Alteromonas macleodii nor for natural samples from the Bay of Marseille, France. Among possible biases, those related to the hydrophobic/hydrophilic conditions required for precipitation are discussed.
Letters in Applied Microbiology, 1997
Journal of Marine Systems, 2001
On the Mediterranean side of the Strait of Gibraltar, the distribution of physical, chemical and ... more On the Mediterranean side of the Strait of Gibraltar, the distribution of physical, chemical and biological variables Ž . temperature, salinity, nutrients, chlorophyll a, lipids, particles size and plankton abundance was examined. Sampling was carried out between the surface and 150 m at a fixed station over a 24-h time series. The patterns observed were related to the overlaying of different processes. The Atlantic-Mediterranean interface acts as a strong pycnocline and its vertical oscillation accounts for the gross distribution of nutrients, particles, and living biomass. Injection of North Atlantic Central Ž . Ž . Water NACW into the upper layer occurs at the sill each semidiurnal tidal cycle every 12 h . As a consequence, in the upper Atlantic layer the NACW was observed every 12 h in the trough of the interface oscillation, whereas Surface Atlantic Ž . Water SAW dominated in the crest at the fixed station. The initially nutrient-rich NACW was associated with eutrophic signatures such as high chlorophyll, large cells and low turbidity; The nutrient depleted SAW was associated with oligotrophic signatures such as low chlorophyll, small cells and high turbidity. The distribution of lipid biotracers at the Ž . depth of the chlorophyll maxima 10-40 m depicted a similar trend with abundant chloroplast lipids and a low lipolysis index in NACW-enriched waters, and a high lipolysis index and abundant zooplankton tracers in SAW especially at night. During the eastward advection of Atlantic water, the nutrient content of NACW is likely to be assimilated by phytoplankton. A scenario is proposed for explaining changes in phytoplankton maxima composition during the time series observations, taking into account the timing of the NACW injection at the sill, the diurnal cycle and zooplankton grazing. Although more studies over a longer temporal scale are necessary to validate this scenario, our observations show the scale of daily variations in the physicalrbiological coupling in the Strait and the implications for nutrient and matter exchanges between the Atlantic and Mediterranean. q
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Papers by Madeleine Goutx