References of "Gobert, Sylvie"
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See detailL’indice paysager Caulerpa racemosa “I.Ca.r”
Cariou, Nicolas; Chery, Aurélia; Jousseaume, Matthieu et al

in Ifremer (Ed.) CARtographie des HAbitats Marins Benthiques : de l'Acquisition à la Restitution (2013, March 27)

Depuis 2002, l’algue invasive Caulerpa racemosa var. cylindracea a été signalée au niveau de la Corse. Elle apparaît pour la première fois, en 2008, au niveau de la baie de Calvi (Corse). Depuis cette ... [more ▼]

Depuis 2002, l’algue invasive Caulerpa racemosa var. cylindracea a été signalée au niveau de la Corse. Elle apparaît pour la première fois, en 2008, au niveau de la baie de Calvi (Corse). Depuis cette époque, le nombre et la surface des sites envahis augmentent. L'analyse fine de l'évolution spatio-temporelle de sa distribution dans la zone prospectée confirme que C. racemosa colonise d'abord les sites profonds. A partir des différents stades de colonisation, un indice paysager (Indice Caulerpa racemosa: "I.Ca.r") adapté à la plongée en scaphandre autonome a été élaboré. "I.Ca.r" qui tient compte de l'expérience du plongeur, du type de substrat et de la superficie colonisée est un code à 8 caractères. Il permet une comparaison spatiale de sites colonisés et également une analyse de l'évolution temporelle de la colonisation. Mis au point en Baie de Calvi, l'indice paysager "I.Ca.r" peut être appliqué sur la Corse et sur l'ensemble de La Méditerranée. La méthodologie simple, résumée sur une fiche pourrait être distribuée dans les clubs de plongée et les informations envoyées au réseau Caulerpe par exemple. [less ▲]

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See detailExperimental in situ exposure of the seagrass Posidonia oceanica (L.) Delile to 15 trace elements
Richir, Jonathan ULg; Luy, Nicolas; Lepoint, Gilles ULg et al

in Aquatic Toxicology (2013), 140-141

The Mediterranean seagrass Posidonia oceanica (L.) Delile has been used for trace element (TE) biomonitoring since decades ago. However, present informations for this bioindicator are limited mainly to ... [more ▼]

The Mediterranean seagrass Posidonia oceanica (L.) Delile has been used for trace element (TE) biomonitoring since decades ago. However, present informations for this bioindicator are limited mainly to plant TE levels, while virtually nothing is known about their fluxes through P. oceanica meadows. We therefore contaminated seagrass bed portions in situ at two experimental TE levels with a mix of 15 TEs (Al, V,Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Ag, Cd, Pb and Bi) to study their uptake and loss kinetics in P. oceanica. Shoots immediately accumulated pollutants from the beginning of exposures. Once contaminations ended, TE concentrations came back to their original levels within two weeks, or at least showed a clear decrease. P. oceanica leaves exhibited different uptake kinetics depending on elements and leaf age: the younger growing leaves forming new tissues incorporated TEs more rapidly than the older senescent leaves. Leaf epiphytes also exhibited a net uptake of most TEs, partly similar to that of P. oceanica shoots. The principal route of TE uptake was through the water column, as no contamination of superficial sediments was observed. However, rhizomes indirectly accumulated many TEs during the overall experiments through leaf to rhizome translocation processes. This study thus experimentally confirmed that P.oceanica shoots are undoubtedly an excellent short-term bioindicator and that long-term accumulations could be recorded in P. oceanica rhizomes. [less ▲]

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See detailSoft-bottom macrobenthos monitoring in the framework of the STARE-CAPMED program
Donnay, Annick ULg; Pelaprat, Corinne; Fréjefond, Charlène et al

in CIESM Congress Proceedings n*40 (2013)

STARE-CAPMED is a research program set up by the Stareso research station (Calvi, Corsica). Its aim is to improve the understanding of processes by which anthropogenic activities have adversed effects on ... [more ▼]

STARE-CAPMED is a research program set up by the Stareso research station (Calvi, Corsica). Its aim is to improve the understanding of processes by which anthropogenic activities have adversed effects on the functioning of Calvi Bay coastal ecosystems. One of its work packages is the monitoring of soft-bottom macrobenthos along 5 gradients of potential anthropogenic pressures. First results suggest that, before summer (summer is the period where man-driven impacts are expected to be stronger due to high tourist frequentation) these sources of potential anthropogenic pressures perturb soft-bottom macrobenthos assemblages. [less ▲]

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See detailAn adapted staining-destaining method to sort soft-bottom macrobenthos mixed with Posidonia oceanica fibers
Donnay, Annick ULg; Pelaprat, C; Lejeune, P et al

in Mediterranean Marine Science (2013), 14(1), 92-94

Sorting   of   soft-­bottom   macrobenthos   entangled   with   Posidonia   oceanica fibers is time-consuming and tedious because of the weak of colour contrast .  This   paper   describes   a   staining ... [more ▼]

Sorting   of   soft-­bottom   macrobenthos   entangled   with   Posidonia   oceanica fibers is time-consuming and tedious because of the weak of colour contrast .  This   paper   describes   a   staining-­destaining   technique   that   produces   good   contrast   between   soft-­bottom   macrobenthos  and  Posidonia  oceanica fibers. The method has been tested on Corsican samples in oligotrophic areas characterized by small-size soft-bottom macrofauna. Our technique saves sorting time (-24%) and is simple to implement. [less ▲]

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See detailIndicateur Angiospermes/Herbiers de Posidonies PREI (Facade Mediterranée, Masses d'eaux Côtières
Gobert, Sylvie ULg

in Guide relatif aux règles d’évaluation de l’état des eaux littorales (eaux côtières et eaux de transition) en vue de la mise à jour de l’état des lieux 2013 (2013)

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See detailEstablishing research strategies, methodologies and technologies to link genomics and proteomics to seagrass productivity, community metabolism, and ecosystem carbon fluxes
Mazzuca, Silvia; Bjork, M; Beer, S et al

in Frontiers in Plant Science (2013), 4(38), 1-19

A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research.This enables the prediction of change and possibly the ... [more ▼]

A complete understanding of the mechanistic basis of marine ecosystem functioning is only possible through integrative and interdisciplinary research.This enables the prediction of change and possibly the mitigation of the consequences of anthropogenic impacts. One major aim of the European Cooperation in Science and Technology (COST) Action ES0609 “Seagrasses productivity. From genes to ecosystem management,” is the calibration and synthesis of various methods and the development of innovative techniques and protocols for studying seagrass ecosystems. During 10 days, 20 researchers representing a range of disciplines (molecular biology, physiology, botany, ecology, oceanography, and underwa- ter acoustics) gathered at The Station de Recherches Sous-marines et Océanographiques (STARESO, Corsica) to study together the nearby Posidonia oceanica meadow. STARESO is located in an oligotrophic area classified as “pristine site” where environmental distur- bances caused by anthropogenic pressure are exceptionally low. The healthy P. oceanica meadow, which grows in front of the research station, colonizes the sea bottom from the surface to 37 m depth. During the study, genomic and proteomic approaches were integrated with ecophysiological and physical approaches with the aim of understanding changes in seagrass productivity and metabolism at different depths and along daily cycles. In this paper we report details on the approaches utilized and we forecast the potential of the data that will come from this synergistic approach not only for P. oceanica but for seagrasses in general. [less ▲]

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See detailJournée de rencontre entre L'institut des Radio-Elements et L'Université de Liège
Debois, Valérie; Gobert, Sylvie ULg

Diverse speeche and writing (2012)

Présentation des activités du CART (Caroline Douny), de l'Unité D'Analyses, Qualité et Risques (JP Bathélémy), du Bureau Envirinnement et Analyses de Gembloux (Ph Maesen), du laboratoire des ressources ... [more ▼]

Présentation des activités du CART (Caroline Douny), de l'Unité D'Analyses, Qualité et Risques (JP Bathélémy), du Bureau Envirinnement et Analyses de Gembloux (Ph Maesen), du laboratoire des ressources Hydriques (V Debbait) et du laboratoire d'Océanologie (S Gobert).Pistes de Collaborations. [less ▲]

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See detailA study of Electra posidoniae Gautier (Cheleistomata, Anasca), a bryozoan strictly found as epiphyte of the seagrass Posidonia oceanica (L.) Delile.
Lepoint, Gilles ULg; Mouchette, Olivier; Pelaprat, Corinne et al

Poster (2012, November 26)

Species living as epiphytes of marine macrophytes have often important role in ecosystem functioning, such as food web suppliers. Some animal or algae species may be considered as really specialised in ... [more ▼]

Species living as epiphytes of marine macrophytes have often important role in ecosystem functioning, such as food web suppliers. Some animal or algae species may be considered as really specialised in the colonization of plant substrate and often dominates epiphytic community, particularly, on long life-span seagrass and macroalgae species. Because epiphytic compartment dysfunction is often implied in seagrass human-induced declining, it is important to understand dynamics and life traits of its specific component in pristine area. In our study, colonization dynamics, biomass seasonality, diet composition of Electra posidoniae, an epiphytic bryozoa, strictly found on the leaves of the seagrass Posidonia oceanica and dominating the leaf epifauna, were assessed monthly at 10 metre depth in the Revellata Bay (Corsica, Mediterranean sea). Aiming to delineate their trophic role in the ecosystem, we have performed bulk stable isotopes measurements and gut content analysis. [less ▲]

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See detailAn overview of the microbenthic loop in Posidonia oceanica meadows: the good, the bad and the ugly
Pete, Dorothée ULg; Quattrocchi, Loïc; Velimirov, Branko et al

in Creed, J.C.; Oigman-Pszczol, S.S. (Eds.) Proceedings of the 10th International Seagrass Biology Workshop (ISBW10), 25- 30 November 2012, Armação dos Búzios, Brazil (2012, November)

Posidonia oceanica is an endemic seagrass of the Mediterranean Sea. The ecosystem based on this plant is essential from an ecological and economical point of view (commercial species, touristic activities ... [more ▼]

Posidonia oceanica is an endemic seagrass of the Mediterranean Sea. The ecosystem based on this plant is essential from an ecological and economical point of view (commercial species, touristic activities, oxygen production), though very sensitive to environmental perturbations. To detect those perturbations, scientists are trying to find more efficient ecological indicators. Most of the time, those indicators are based on the plant itself. Unfortunately, this seagrass does not react very quickly to perturbations so, when a reaction is noticed, it is often too late to prevent irremediable damages to the ecosystem. The sedimentary compartment of P. oceanica meadows has been less studied than the canopy level. However, it could be a good source of ecological indicators because it is the final container of all the pollution. In this framework, the microbenthic loop has been studied. It is a major subsystem of those meadows and encompasses organic matter, bacteria, microphytobenthos and meiofauna. As those organisms have a rapid turnover and stay almost all their life inside the sediment, they seemed good potential indicators. This presentation will show what is useful or not inside the sediment and more specifically inside the microbenthic loop. Results of a comparison between a fish farm and a reference location will be used, as well as in situ experiments (shading and sediment loading) and small spatial scale variations. At the end of this presentation, you will know what are the good, the bad and the ugly in the sedimentary compartment of a P. oceanica meadow. [less ▲]

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See detailSeagrass productivity, from genes to ecosystem management - benthic incubations
Gobert, Sylvie ULg; Lepoint, G.; Richir, Jonathan ULg et al

Scientific conference (2012, October 09)

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See detailTrophic tracers reveal considerable diversity among diets of dominant amphipods from Posidonia oceanica seagrass meadows
Michel, Loïc ULg; Dauby, Patrick ULg; Gobert, Sylvie ULg et al

Poster (2012, August 20)

Mediterranean Posidonia oceanica meadows shelter a high biomass and an important biodiversity of amphipod crustaceans. In other temperate meadows, the amphipods play an important part in the functioning ... [more ▼]

Mediterranean Posidonia oceanica meadows shelter a high biomass and an important biodiversity of amphipod crustaceans. In other temperate meadows, the amphipods play an important part in the functioning of the ecosystem, notably in organic matter transfers from producers to higher level consumers. However, the situation in Posidonia oceanica meadows remains unclear, and little is known about the trophic ecology of amphipods, which are generally regarded as generalist herbivores/detritivores despite the lack of precise studies. Here, we combined gut content examination and trophic markers (fatty acids, stables isotopes of C and N) to delineate the diet of the dominant species of amphipods from Posidonia oceanica seagrass meadows and to highlight trophic diversity among this community. Our results indicate that contribution of microepiphytic diatoms and of benthic and suspended particulate organic matter to the diet of amphipods were anecdotal. On the other hand, all dominant species heavily relied on macroalgal epiphytes, suggesting a certain extent of overlapping in the diets of the dominant species. Considerable interspecific differences nonetheless existed, notably concerning grazing preferences towards epiphytes from leaves or litter fragments vs. epiphytes from rhizomes. In addition, the use of the SIAR isotopic mixing model showed that most species had a mixed diet, and relied on several food items. None of the examined species seemed to graze on their seagrass host, but Gammarus aequicauda partly relied on seagrass leaf detritus. Overall, our findings demonstrate that amphipods have the potential to be key-items in trophic and functional interactions occurring among Mediterranean Posidonia oceanica meadows. [less ▲]

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See detailL'océanographie , c'est quoi?
Gobert, Sylvie ULg

Conference given outside the academic context (2012)

Présentation de l'océanographie: définition, notion de base, histoire de l'océanographie à Liège

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See detailAssessment of the ecological status of P. oceanica meadow with a no destructive shoot method
Gobert, Sylvie ULg; Lejeune, Pierre ULg; Chéry, Aurélia et al

in Proceedings of the Mediterranean Seagrass Workshop 2012 (2012, June)

Posidonia oceanica (L.) Delile is a protected species, included in the Red list of marine threatened species of the Mediterranean. Because of its sensitivity to disturbance, P. oceanica is used as a ... [more ▼]

Posidonia oceanica (L.) Delile is a protected species, included in the Red list of marine threatened species of the Mediterranean. Because of its sensitivity to disturbance, P. oceanica is used as a bioindicator to define the health status of coastal waters. Monitoring methods generally require to sample plants, followed by measurements on picked shoots. This implies the total destruction of several tens of shoots. This study presents a method, “The Non Destructive Shoot Methodology”: NDSM, that permits the measurement of (1) the most used seagrass metrics, (2) the determination of C, N, P contents and (3) the measurement of the trace metal levels in P. oceanica leaves. Our technic has been firstly tested by comparison with the results obtained with classic method of biometry. Secondly, differences between levels of C, N, P and trace metals obtained with classic picking and our methodology were tested. Thirdly, the physiological consequences on the shoots were investigated (% of survival, growth, essential element contents (C, N, P, Fe, Cu...). The NDSM gives similar results to classic investigations to assess the ecological status of P. oceanica meadow (i.e. PREI, BiPO...) and avoid the uprooting of the “K-strategist” protected species. This methodology is usable in cases of monitoring and impact studies. [less ▲]

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See detailSeasonal and depth-related distributions of epiphytic Bryozoa in a Mediterranean seagrass meadow
Lepoint, Gilles ULg; Balancier, Boris; Gobert, Sylvie ULg

Poster (2012, May 31)

Although biofouling on Posidonia oceanica (L.) Delile is thought to be driven by the variability of environmental parameters and phenology of the plant, effect of these parameters on sessile animal ... [more ▼]

Although biofouling on Posidonia oceanica (L.) Delile is thought to be driven by the variability of environmental parameters and phenology of the plant, effect of these parameters on sessile animal colonization is still poorly understood. This study aims to document the seasonality and the bathymetric variability of epiphytic Bryozoa diversity and abundance on this seagrass Posidonia shoots were collected in the Revellata bay (Corsica, Mediterranean) in five seasons from 7 to 30 m depth. Colony densities may reach more than 87000 colonies. m-2 at 10 m depth in spring; this probably implies an important contribution of Bryozoa larvae to spring plankton where P. oceanica meadows are present. The Bryozoa specific distribution and abundance appeared to be determined by the seasonality of both the environmental parameters and the plant phenology. However, depth and associated environmental gradients played a structuring role. Based on our data and on the literature, we propose a classification of epiphytic Bryozoa in four categories from hyper-epiphytic specialist to accidental epiphytes and underline the necessity to protect seagrass systems on their full depth range to maximize biodiversity conservation. [less ▲]

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See detailTrace element kinetics in contaminated Posidonia oceanica meadow
Richir, Jonathan ULg; Luy, Nicolas; Lepoint, Gilles ULg et al

in Proceedings of the Mediterranean Seagrass Workshop 2012 (2012, May 29)

The seagrass Posidonia oceanica (L.) Delile is widely used since the mid-70th to biomonitor trace elements (TEs). However, there is a lack of knowledge regarding to pollutant kinetics in that species ... [more ▼]

The seagrass Posidonia oceanica (L.) Delile is widely used since the mid-70th to biomonitor trace elements (TEs). However, there is a lack of knowledge regarding to pollutant kinetics in that species. Posidonia oceanica were in situ contaminated by a mix of 15 TEs (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Ag, Cd, Pb and Bi) at experimental levels equivalent to 10 (moderate) and 100 (acute) times seawater average concentrations. TEs concentrations were measured by ICP-MS in P. oceanica leaves and rhizomes sampled at regular time intervals, in epiphytes, in water and in sediment. Posidonia oceanica immediately accumulated pollutants from the beginning of experiments; once contaminations ended, TE concentrations came back to their original levels within two weeks, or at least showed a clear decrease. Leaves exhibited different uptake kinetics for many elements (e.g. Cr, Cu, Ag, Bi etc.): the younger growing leaves forming new tissues incorporated chemicals more rapidly than the older senescent leaves. Rhizomes did not show any clear trend, except for Cu, Zn and Bi. Results demonstrate that P. oceanica is a very sensitive sentinel to immediately delineate punctual pollutions similar to what might be measured in contaminated Mediterranean waters. The good response of P. oceanica leaves to pollutant short-term expositions suggests their routine use in regularly scheduled monitoring programs. Nevertheless, to by-pass P. oceanica leaves deciduous character and their capability to detoxify rapidly, long term accumulation recordings would also necessitate belowground tissues analyses. [less ▲]

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See detailStare-Capmed : Présentation générale du projet et exemple d'une action : "Impact de l'ancrage sur la dynamique des herbiers de posidonies".
Michel, Loïc ULg; Champenois, Willy ULg; Borges, Alberto ULg et al

Conference (2012, May 16)

STARE-CAPMED (STAtion of Reference and rEsearch on Change of local and global Anthropogenic Pressures on Mediterranean Ecosystems Drifts) est un projet de recherche mis en place par Stareso S.A.S. depuis ... [more ▼]

STARE-CAPMED (STAtion of Reference and rEsearch on Change of local and global Anthropogenic Pressures on Mediterranean Ecosystems Drifts) est un projet de recherche mis en place par Stareso S.A.S. depuis janvier 2012. Il a pour objectif d’établir un site de référence à long terme pour la compréhension, par la recherche fondamentale, des processus de l’évolution des écosystèmes méditerranéens côtiers et océaniques en réponse aux changements actuels globaux et locaux des pressions anthropiques. Centré sur la Baie de Calvi et le proche large, il vise à fournir un référentiel basé sur des mesures à haute fréquence qui doivent pouvoir complémenter les réseaux de surveillance basse fréquence et de recherches existants et ainsi faire progresser la compréhension des processus. En outre, le projet doit fournir aux utilisateurs finaux (collectivités locales et régionales, administrations nationales, ...) des orientations de gestion basées sur l’analyse étayée des processus en jeux. Financé par l’Agence de l’eau RMC et la Collectivité Territoriale de Corse, le projet, multidisciplinaire, se décline actuellement selon 10 axes de travail : • Suivi du cadre hydrographique et physico-chimique • Suivi et quantification des pressions anthropiques • Ecosystème planctonique • Benthos de substrat meuble • Benthos de substrat dur et faune vagile • Phanérogames marines et écosystèmes associés • Mouillages et processus d’altération des herbiers de posidonies • Ecotoxicologie et polluants émergents • Bilan CO2 et métabolisme des écosystèmes • Zones protégées, espèces nouvelles, recrutement Pour chacun de ces axes, la stratégie d’échantillonnage est basée sur la comparaison de données obtenues durant des périodes où l’impact anthropique est faible (octobre-avril) avec celles obtenues durant des périodes de pression intense (mai-septembre), et sur la comparaison de données issues de sites de référence peu impactés avec celles provenant de sites où l’impact anthropique est reconnu. A titre d’exemple, le but de l’action "Mouillages et processus d’altération des herbiers de posidonies" est de mettre en évidence les conséquences des altérations liées à l’arrachage de faisceaux de posidonies sur la vitalité de l’herbier. Des zones où la pression de mouillage est reconnue seront définies sur base des travaux de cartographie de l’herbier, également réalisés dans le cadre du projet STARE-CAPMED. Elles seront comparées avec des zones d’herbiers sains témoins par la caractérisation du sédiment (mesures de compacité in situ, mesures des concentrations en O2 et nutriments et du pH de l’eau interstitielle, granulométrie et teneur en matière organique du sédiment, proportions de rhizomes et morts) ainsi que par la définition de l’état physiologique des faisceaux de posidonies (mesures biométriques classiques, analyses des contenus élémentaires en carbone, azote et phosphore) et par l’application d’indices écologiques définis par la DCE (PREI, BIPO, …). Les résultats obtenus permettront d’avoir une vue d’ensemble des processus par lesquels l’impact physique des mouillages de bateaux de plaisance occasionne des dégâts aux herbiers de posidonies. Ils pourront ainsi fournir une base de connaissances solide aux gestionnaires soucieux de limiter cet impact. [less ▲]

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See detailSeagrass productivity, from genes to ecosystem management
Gobert, Sylvie ULg; Lepoint, G.; Richir, Jonathan ULg et al

Scientific conference (2012, May 07)

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See detailChemical contamination along the Mediterranean French coast using Posidonia oceanica (L.) Delile above-ground tissues: a multiple trace element study
Luy, Nicolas; Gobert, Sylvie ULg; Sartoretto, Stéphane et al

in Ecological Indicators (2012), 18

Levels of Be, Al, V, Mn, Co, As, Se, Mo, Ag, Sn, Sb, Bi as well as of Cr, Fe, Ni, Cu, Zn, Cd and Pb in Posidonia oceanica (L.) Delile from the Mediterranean French coast were analysed using DRC ICP-MS ... [more ▼]

Levels of Be, Al, V, Mn, Co, As, Se, Mo, Ag, Sn, Sb, Bi as well as of Cr, Fe, Ni, Cu, Zn, Cd and Pb in Posidonia oceanica (L.) Delile from the Mediterranean French coast were analysed using DRC ICP-MS. The first twelve elements have not been well studied and can be considered to be potential pollutants as a result of potentially increased levels resulting from anthropogenic activities. Spatial variation and/or compartmentalization were found for all trace elements. Except for Al, Cr, Fe, Cu and Ag, most trace elements were preferentially accumulated in photosynthetic tissues, suggesting uptake from the water column. Moreover, for Be, V, Mn, Co, Ni, As, Mo, Sb, Sn and Pb, adult leaves had higher levels than intermediate leaves, suggesting low kinetics of accumulation. Levels in the third intermediate leaf were representative of the average levels of the integral shoot, and thus can be used alone in chemical biomonitoring. For most of the twelve little-studied trace elements, the background levels of the northwestern Mediterranean Sea can be measured, and their spatial variation can be related to anthropogenic activities. Levels of the seven widely studied trace elements seem to decrease or stabilize over time, probably due to their reduced anthropogenic use. These observations show that P. oceanica is a sensitive bioindicator for the monitoring of chemical contamination of a large number of trace elements. [less ▲]

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See detailUse of semi-quantitative kit methods to study the heterotrophic bacterial community of Posidonia oceanica meadows: Limits and possible applications
Richir, Jonathan ULg; Velimirov, Branko; Poulicek, Mathieu ULg et al

in Estuarine Coastal & Shelf Science (2012), 109

Rapid, easy and low cost semi-quantitative methods were tested to study the heterotrophic bacterial community of Posidonia oceanica meadows and were compared to techniques commonly used in microbial ... [more ▼]

Rapid, easy and low cost semi-quantitative methods were tested to study the heterotrophic bacterial community of Posidonia oceanica meadows and were compared to techniques commonly used in microbial ecology. Free and pore-water bacterial densities were estimated by luminescence, and principal enzymatic activities, metabolic capabilities and benthic mineralisation processes were studied with microtitration methods: ApiZym galleries, Biolog microplates and BART tests. Bacterial densities varied little throughout the year and were around 5.0 10^5 and 6.0 10^6 cells ml -1 of free and pore-water, respectively. The combined use of the ApiZym gallery and the Biolog microtitration plate permitted highlighting bacterial enzymatic activities susceptible to degrade principal organic polymers present in the Posidonia meadow, and to correlate these enzymatic activities to the subsequent potential utilization of resulting monomeric products. Levels of enzymatic activities (1.80-8.36 nmoles substrates h -1 ml- 1) and energetic bacterial metabolism (1.80-6.42 nmoles substrates h -1 ml- 1) presented seasonality relying on the temperature regime and on the primary production (Posidonia and phytoplankton). Main mineralization processes of buried organic matter through sulfate and iron reduction activities were successfully detected. Despite the complexity of the studied ecosystem, results obtained by this semi-quantitative approach, compared to studies applying commonly used methods in microbial ecology, highlighted the same bacterial dominant key processes. Their low cost, rapid and easy use, and the low level of expertise and sophistication they require means that these techniques are of use to many employed in environmental surveys. [less ▲]

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