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See detailRecent advances in the biomonitoring of trace elements using P. oceanica (L.) Delile
Gobert, Sylvie ULg; Richir, Jonathan ULg

in CIESM Congress Proceedings n°40 (in press)

One of the most studied bioindicator in the Mediterranean is the seagrass Posidonia oceanica. Trace element (TE) monitoring surveys using that species have however mostly focussed on a few elements (e.g ... [more ▼]

One of the most studied bioindicator in the Mediterranean is the seagrass Posidonia oceanica. Trace element (TE) monitoring surveys using that species have however mostly focussed on a few elements (e.g. Pb, Cd), while numerous others, efficiently bioconcentrated by the plant and potentially toxic, have been barely or not studied (e.g. Ag, V, Bi). Furthermore, although P. oceanica bioaccumulation behaviour relies on synergistic effects between the sampling environment and its ecophysiology, this aspect has been mostly underestimated until now. This study presents recent advances in the biomonitoring of TEs using P. oceanica and insists on the necessity of developing consensual monitoring protocols in order to improve its use as bioindicator. [less ▲]

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See detailNew insights for an old topic: seagrasses as bioindicators of coastal trace element pollution
Richir, Jonathan ULg; Lejeune, Pierre; Gobert, Sylvie ULg

in ARGYRO ZENETOS, ZENETOS (Ed.) Mediterranean Marine Science (2014, March)

The marine magnoliophyte Posidonia oceanica (L.) Delile has been widely used since the mid-70th to biomonitor the coastal pollution of the Mediterranean in Cr, Ni, Cu, Zn, Cd, Pb and/or Fe. In contrast ... [more ▼]

The marine magnoliophyte Posidonia oceanica (L.) Delile has been widely used since the mid-70th to biomonitor the coastal pollution of the Mediterranean in Cr, Ni, Cu, Zn, Cd, Pb and/or Fe. In contrast, other trace elements (TEs) like As, V, Ag, Be, Al, Mn, Co, Se, Mo, Sn, Sb and Bi, many of them categorized as TEs of environmental emerging concern, have been subject to nearly no ecotoxicological survey with that species. It has been shown that the French Mediterranean littoral was submitted to local, diffuse and/or chronic contaminations both by TEs broadly or little biomonitored with P. oceanica; high TE levels could further be linked to specific anthropic activities such as agriculture (Mo), mining (Cr, Sb, Zn), industries (As), storage and refinement of oil products (V, Pb) or presence of major ports and urban centres (Sn, Bi, Ag). It seems therefore necessary to expand the short list of the seven metals commonly monitored to other TEs, what is today easily achievable as current analytical methods allow the simultaneous determination of all a series of TEs within the same sample. Furthermore, only a multielement analysis in appropriate bioindicator species allow to correctly intercompare the pollution status of numerous sampling sites. To do this, we have calculated proper environmental indices, the trace element pollution index TEPI and the trace element spatial variation index TESVI. The TEPI is an index of the global contamination of a site, giving the same weight to each TE after mean normalization of their environmental concentrations. The TESVI estimates the global spatial variability of environmental concentrations of each TE levels, taking into account both punctual contaminations in impacted sites and the overall coastal spatial heterogeneity between all monitored sites.These two indices were successfully applied both at large (French Mediterranean littoral) and small (a Bay) spatial scales. Furthermore, they can be used in the framework of an intercomparative study compiling data from any previous monitoring surveys. We also highlighted that the ecophysiology and surrounding levels of TEs influenced in an equivalent manner the bioaccumulation process of TEs in P. oceanica. Consequently, this natural cyclic evolution of TE concentrations should be systematically quantified in regional reference sites. Finally, the rapid and proportionnal accumulation of TEs in P. oceanica traps huge amounts of contaminants and can stock them for longer periods of time in their bellow grounds tissues. P. oceanica meadows therefore play an efficient role of natural filter of TE coastal pollutions. [less ▲]

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See detailThe effect of size, weight, body compartment, sex and reproductive status on the bioaccumulation of 19 trace elements in rope-grown Mytilus galloprovincialis
Richir, Jonathan ULg; Gobert, Sylvie ULg

in Ecological Indicators (2014), 36

Numerous trace elements (TEs) can be considered as potential pollutants of the environment, their mining productions and industrial uses increasing worldwide. Their monitoring can be achieved through the ... [more ▼]

Numerous trace elements (TEs) can be considered as potential pollutants of the environment, their mining productions and industrial uses increasing worldwide. Their monitoring can be achieved through the use of bioindicator species, such as the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819). That species has been widely used to monitor the chemical pollution of coastal ecosystems by Cr, Ni, Cu, Zn, Cd, Pb, As, Ag and V. Conversely, environmental levels of Be, Al, Fe, Mn, Co, Se, Mo, Sn, Sb and Bi have been little or not monitored so far in mussel watch programs. Bioaccumulation processes of these 19 TEs in rope-grown M. galloprovincialis purchased from a salt pond with good chemical water quality were thus investigated in the present study. Mussels efficiently accumulated the 19 studied TEs. Bioaccumulation processes were driven by numerous mutually dependent biological parameters such as the mussel size and flesh weight, the sex and the reproductive status and the body compartment considered. TE bioaccumulation was a power function of the mussel soft body dry weight; total contents linearly increased with the shell length. Small-size mussels overall concentrated more TEs, with a high inter-individual variability, consequently influencing the modelling of their bioaccumulation in the whole rope population. Although a large range of rope-grown M. galloprovincialis sizes can be used for monitoring purposes, one will thus take care not to use extreme size individuals. The influence of gametogenesis in determining female body higher TE concentrations prior to spawning could not be neglected and varied depending on the element. TEs were preferentially accumulated in the hepatopancreas, except for Zn, Se, Cd and Mo, more concentrated in gills. Gametogenesis did not influence TE distribution between body compartments, but likely diluted their concentrations as a direct consequence of massive reproductive tissue production. So, results from the present study underline the potential use of M. galloprovincialis in the biomonitoring of numerous little studied TEs and give some insights into the decisive role played by some relevant biological parameters in bioaccumulation processes of the 19 investigated TEs in rope-grown mussels. [less ▲]

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See detailThe underestimation of seagrass biological cycle in the biomonitoring of coastal trace element pollution
Richir, Jonathan ULg; Sartoretto, Stéphane; Gobert, Sylvie ULg

Poster (2013, December)

Previous monitoring surveys using the Mediterranean seagrass Posidonia oceanica (L.) Delile mostly studied coastal pollutions in Cr, Ni, Cu, Zn, Cd, Pb and/or Fe and the distribution of their ... [more ▼]

Previous monitoring surveys using the Mediterranean seagrass Posidonia oceanica (L.) Delile mostly studied coastal pollutions in Cr, Ni, Cu, Zn, Cd, Pb and/or Fe and the distribution of their bioaccumulated levels between the seagrass compartments. In contrast, other trace elements (TEs) like As, V, Ag, Be, Al, Mn, Co, Se, Mo, Sn, Sb and Bi, many of them categorized as TEs of environmental emerging concern, have been subject to nearly no ecotoxicological survey with that species. Moreover, the understanding of the seasonal variation of TE levels according to the seagrass biological cycle, a prerequisite to the intercomparison of sites sampled at different periods of the year, has been little investigated. P. oceanica were thus seasonally collected for TE analyses from March 2008 to November 2010 in the Calvi Bay (Corsica, France), a reference site for the northwestern Mediterranean, and near the sewer outfall of Marseille city (France). Results showed that levels of the 19 studied TEs evolved seasonally according to the seagrass biological cycle. So, foliar levels of Cr, Pb, Mn or Bi, preferentially accumulated in older leaves, increased from spring to autumn, as the number of adult leaves. V, Se, As or Sb evolved similarly to the shoot foliar surface, reflecting the plant growth. Cu levels, an essential micronutrient, were lower when summer requirements for leaf growth were high. Al foliar levels evolved similarly to rhizome and root levels, resulting from its acropetal translocation. However, in the anthropized Marseille site, environmental variables non-intrinsic to the seagrass ecophysiology could perturb this seasonal variation. This survey allowed highlighting the proportionally equivalent roles played by both the seagrass biological cycle and its environment in the bioaccumulation process of TEs. This cyclic evolution should therefore be systematically quantified in regional reference sites in order to properly intercompare results from biomonitoring surveys. [less ▲]

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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 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 detailCoastal pollution of the Mediterranean and extension of its biomonitoring to trace elements of emerging concern
Richir, Jonathan ULg

Doctoral thesis (2012)

The Mediterranean Sea, a semi-enclosed sea with densely populated coasts, is submitted to numerous anthropogenic pressures: among them, the chemical pollution by traces elements. These pollutants, coming ... [more ▼]

The Mediterranean Sea, a semi-enclosed sea with densely populated coasts, is submitted to numerous anthropogenic pressures: among them, the chemical pollution by traces elements. These pollutants, coming from our continental activities, are transported through rivers or by air and accumulate in seas and oceans where they mainly affect coastal areas. During the 70ies, scientists suggested to use organisms, in particular mussels of the genus Mytilus, in order to evaluate the status of chemical contamination of coastal ecosystems. Biomonitoring was born. Since, many monitoring studies were published using various animal and vegetal species. Two of the most studied bioindicators species in the Mediterranean are the marine magnoliophyte Posidonia oceanica and the Mediterranean mussel Mytilus galloprovincialis. Monitoring studies with these two species have mainly focussed on contaminations by Cr, Ni, Cu, Zn, Cd, Pb (Mytilus galloprovincialis and Posidonia oceanica), Fe (Posidonia oceanica), As, V and Ag (Mytilus galloprovincialis). However, other trace elements like Be, Al, Mn, Co, Se, Mo, Sn, Sb and Bi have been subject to nearly no ecotoxicological survey. Furthermore the worldwide evolution of our technologies and of our lifestyle increases the extraction and production of trace elements (notably to answer needs of developing countries). The biomonitoring of the pollution by trace elements is henceforth a topical subject. The overall objective of this work was therefore to evaluate the potential use of Mytilus galloprovincialis and Posidonia oceanica as bioindicators to monitor the Mediterranean coastal pollution by Be, Al, Mn, Co, Se, Mo, Sn, Sb, Bi, Fe, As, V, and Ag. These trace elements, mostly little studied, can be categorized as elements of “environmental emerging concern”. A time-integrated efficient monitoring of trace elements requires the continuous survey of their environmental levels; we therefore also measured levels of trace elements classically monitored with these two species. Mytilus galloprovincialis and Posidonia oceanica complement each other in monitoring surveys. Both species accumulate pollutants dissolved in the water column. Posidonia oceanica, rooted in the seafloor, accumulates moreover pollutants stored in sediments in the long term. Mytilus galloprovincialis, as a filter feeder, further accumulate particulate pollutants suspended in the water column. The combined use of both bioindicators therefore provides a global view of the health status of the coastal environment (water, sediments, suspended matter). Our first goal was to measure, at the scale of the French Mediterranean littoral, the spatial variability of trace element contents in Posidonia oceanica, and to determine if trace elements of environmental emerging concern threaten the chemical integrity of coastal ecosystems. We observed that the large majority of trace elements little or no monitored with Posidonia oceanica showed an equivalent to higher spatial variability than elements classically monitored with that species. We also showed that the spatial variability could be associated to specific anthropic activities like agriculture (Mo), mining (Sb), storage and refinement of oil products (V), or the presence of harbours and major urban centres (Sn, Bi). Their monitoring, along with the one of trace elements classically studied in the Mediterranean, turns out to be essential. In addition, the in-depth study of the contamination state of the Calvi Bay (Northwestern coast of Corsica, France), enabled us to define (or re-define) this site as a reference site for the monitoring of the chemical pollution by trace elements in the Northwestern Mediterranean. We further studied the physiological mechanisms of accumulation, storage and excretion of trace elements by Posidonia oceanica. In situ contamination of seagrass bed portions allowed us to model the rapid kinetics of accumulation of contaminants by Posidonia oceanica shoots. Compartments of the plant answered differently to pollutant exposures. So, adult and senescent leaves assimilated pollutants less rapidly than young actively growing leaves. Trace elements, once accumulated, could be redistributed between the plant compartments, notably towards the rhizomes-roots systems buried in sediments. Our results experimentally showed that these below-ground organs could therefore play the role of biological archives for many elements. At the end of periods of exposure to pollutants, kinetics of decontaminations of Posidonia oceanica shoots were relatively fast and depended notably on the duration of the exposure to trace elements, on their toxic or essential character and on the studied compartment. We concluded that Posidonia oceanica was a sensitive bioindicator for the monitoring of the past and present coastal pollution by trace elements. We showed that Mytilus galloprovincialis efficiently accumulated trace elements of environmental emerging concern as well as elements classically studied with this bioindicator species. The physiology of mussels further conditioned their answers to pollutant exposures. Their reproductive cycle dissolved trace element concentrations during the massive production of gametes and conducted to differences more or less important between individuals of both sexes. The conservative character of the distribution of trace elements between the different body compartments of Mytilus galloprovincialis suggested an important physiological regulation of their internal levels. Finally, the size of mussels used in this study, harvested from an aquaculture farm, did not noticeably influence inter-individual concentrations, all mussels of a same rope having approximately the same age. In conclusion, this study enabled to improve and enlarge our state of knowledge about the monitoring of the pollution of the Mediterranean coastal environment by trace elements. In particular, both Mytilus galloprovincialis and Posidonia oceanica showed to be good candidates for the monitoring of trace elements of environmental emerging concern. [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 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 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 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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See detailAssessment of Mytilus galloprovincialis to monitor 19 trace elements in the Calvi Bay
Richir, Jonathan ULg; Vermeulen, Simon; Biondo, Renzo ULg et al

Poster (2011, December 08)

Mussel caging with Mytilus galloprovincialis has been successively used to monitor classic trace metal (Cd, Cu, Zn, Cr, Fe, Ni, Pb) pollution of Mediterranean coastal waters at spatial scales ranging from ... [more ▼]

Mussel caging with Mytilus galloprovincialis has been successively used to monitor classic trace metal (Cd, Cu, Zn, Cr, Fe, Ni, Pb) pollution of Mediterranean coastal waters at spatial scales ranging from 10 to 100km. However, its relevance as bioindicator at smaller scales (100 m - 1 km) is poorly known. Moreover, the levels of some little studied trace elements (Al, V, Mn, Sb, Sn, Ag, Mo, Se, As, Co, Be, Bi), recently identified as potential pollutants of coastal environments, have not yet been assessed in that species. In this work, M. galloprovincialis was used to monitor the 19 listed trace elements at the scale of the Calvi Bay (NW Corsica, France). Additionally, we investigated decontamination kinetics and trace element tissue speciation before and after spawning. Mytilus galloprovincialis trace element levels reflect the good water quality of the Calvi Bay, showing little spatial variations either at 100m or 1km scales. Filter feeders are only influenced by their relatively homogeneous pelagic environment (dissolved trace elements and suspended particulate matters), in contrast to organisms which inhabit typically heterogeneous benthic habitats. This bioindicator, a convincing candidate for the monitoring of the 12 little studied trace elements, effectively accumulates the 19 studied elements to 105 seawater concentrations. Mytilus galloprovincialis rapidly equilibrates (within days) with its environment, and is therefore a good indicator of chronic and stable chemical pollutions. Tissue speciation shows that the most relevant organ to monitor trace elements is the hepatopancreas. However, the important variability induced by the reproductive cycle of mussels requires using this bioindicator during its sexual dormancy. [less ▲]

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See detailContamination of the Marine Environment by trace metals: old and emergent elements, case studies and perspectives
Gobert, Sylvie ULg; Richir, Jonathan ULg

Scientific conference (2011, November 25)

Presentation of 18 trace elements (old: Cd, Ni, Cu, Zn, Cr, Pb, Fe ; emergent: Be, Al, V, Mn, Sb, As, Bi, Se, Mo, Ag, Sn studied in the laboratory of Oceanology. Study cases in the Mediterranaen Sea ... [more ▼]

Presentation of 18 trace elements (old: Cd, Ni, Cu, Zn, Cr, Pb, Fe ; emergent: Be, Al, V, Mn, Sb, As, Bi, Se, Mo, Ag, Sn studied in the laboratory of Oceanology. Study cases in the Mediterranaen Sea (Seagrass, mussel, seaurchin). [less ▲]

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See detailSeagrass response to in situ trace element contaminations
Richir, Jonathan ULg; Luy, Nicolas; Lepoint, Gilles ULg et al

Poster (2011, September)

The Mediterranean seagrass Posidonia oceanica (L.) Delile has been widely used since the mid-seventies as bioindicator to monitor trace element (TE) coastal pollution. However, there is a lack of ... [more ▼]

The Mediterranean seagrass Posidonia oceanica (L.) Delile has been widely used since the mid-seventies as bioindicator to monitor trace element (TE) coastal pollution. However, there is a lack of knowledge regarding to that seagrass contamination and decontamination kinetics. For the first time, Posidonia were experimentally in situ contaminated in 2009, at 10m depth in Calvi Bay (Corsica), by a mix of 15 TE (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Ag, Cd, Pb and Bi). Trace element concentrations were measured by DRC-ICP-MS in leaves, rhizomes and in overall shoots sampled at regular time intervals. P. oceanica immediately accumulated pollutants from the beginning of experiments; once contaminations ended, TE concentrations came back close to their original levels within 2 weeks, or at least showed a clear decrease. Posidonia leaves exhibited different uptake kinetics for many elements (Cr, Cu, Zn, Ag, Cd, Pb and Bi): the younger growing leaves incorporated chemicals more rapidly than the older ones. Rhizomes did not show any clear trend, except for Cu, Zn and Bi. These results demonstrate that Posidonia is a very sensitive sentinel to immediately delineate punctual pollutions similar to what might be measured in contaminated Mediterranean waters. The very good response of Posidonia leaves to pollutant short term expositions suggests their routine use in regularly scheduled monitoring programs. Nevertheless, to by-pass Posidonia leaves deciduous character and their capability to detoxify rapidly, long term accumulation recordings also necessitate below-ground tissues analyses. [less ▲]

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See detailCombined utilization of DGTs and bioindicators to trace chemical contamination threats on coastal ecosystems
Richir, Jonathan ULg; Luy, Nicolas; Serpe, Pierre et al

Conference (2011, May 03)

Trace metal monitoring in marine organisms and their living habitats permit to trace chronic or acute contaminations of marine ecosystems due to human activities. While dissolved trace metal ... [more ▼]

Trace metal monitoring in marine organisms and their living habitats permit to trace chronic or acute contaminations of marine ecosystems due to human activities. While dissolved trace metal concentrations give us an overall and punctual view over biota contamination status, bioindicator species put their bioavailable and possible toxic fraction in an obvious. However, difficulties mainly inherent to metal measurements in seawater lead field ecotoxicologists to study marine pollution essentially through the use of bioindicators alone. The technique of diffusive gradients in thin films (DGT) for the measurement of trace metals in aqueous solutions was introduced in the mid-ninetieth by Davison and Zhang. This passive probe accumulates labile trace metal species in proportion to their bulk environmental concentrations by maintaining a negative gradient between the environment and an ion-exchange resin (Chelex). DGTs average natural water trace metal concentrations over the deployment period, concentrate them and avoid matrix interferences, notably due to dissolved salts in seawater. Their deployment in passive and experimental monitoring studies permits to reliably measure labile trace metal concentrations and, jointly analysed with bioindicators, to estimate their bioavailability to marine organisms. This combined approach DGT-bioindicator was investigated in Calvi Bay (Corsica) through three monitoring studies. (1) DGTs were deployed in Posidonia oceanica bed, a Mediterranean seagrass forming dense meadows from the surface down to 40 meters depth, to study seasonal, spatial and bathymetrical variations of labile trace metal concentrations within this meadow. These concentrations were analysed jointly with Posidonia trace metal contents in order to quantify their bioaccumulation towards this primary producer, taking into account the seagrass biological cycle. (2) Portions of Posidonia meadow were also in situ experimentally contaminated with a mix of dissolved metals to study seagrass kinetics of pollutant accumulation and decontamination. Thanks to DGTs deployed inside contaminated mesocosms throughout experiments, Posidonia responses to known metal concentrations could be precisely quantified. (3) The blue mussel Mytilus galloprovincialis is widely used in trace metal monitoring programs. Mussels, stored in conchylicultural pouches, were transplanted for 3 months in contrasted stations of Calvi Bay (e.g. aquaculture farm, sewer, etc.) in parallel with DGTs. Such as for Posidonia, the complementary utilization of DGTs and mussels permitted to describe water contamination levels at the scale of the Bay, and their bioaccumulation towards mussels. These 3 studies demonstrate the usefulness of DGTs to monitor labile trace metals in an ecological and ecosystemic approach, in parallel with marine organisms, both indicators furnishing different and complementary informations about ecosystem functioning. [less ▲]

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See detailPosidonia oceanica (L.) Delile, a usefull tool for the biomonitoring of chemical contamination along the Mediterranean coast: a multiple trace element study
Richir, Jonathan ULg; Gobert, Sylvie ULg; Sartoretto, Stéphane et al

in 4th Mediterranean Symposium on Marine Vegetation (2010)

The concentrations of 19 trace elements (TE): Be, Al, V, Mn, Co, As, Se, Mo, Ag, Sn, Sb and Bi as well as Cr, Fe, Ni, Cu, Zn, Cd and Pb, were analyzed by DRC ICP-MS in Posidonia oceanica (L.) Delile ... [more ▼]

The concentrations of 19 trace elements (TE): Be, Al, V, Mn, Co, As, Se, Mo, Ag, Sn, Sb and Bi as well as Cr, Fe, Ni, Cu, Zn, Cd and Pb, were analyzed by DRC ICP-MS in Posidonia oceanica (L.) Delile leaves from the Mediterranean French coast. The first 12 TE have little been studied nowadays. Except for Al, Cr, Fe, Cu and Ag, TE were preferentially accumulated in photosynthetic part of leaves. Moreover, trace element concentrations of the third intermediate leaf are representative of the integral shoot, and could be used alone in biomonitoring. Environmental background concentrations of the 12 little studied TE were determined, and spatial variations were related to anthropic activities. Compared to previous publications, concentrations of the 7 other TE classically investigated present a diminution or a stabilization, reflecting the change of anthropogenic inflows. In conclusion, P. oceanica is a sensitive bioindicator for chemical contamination, even for the twelve little studied TE. [less ▲]

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