References of "Gobert, Sylvie"
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See detailDominant amphipods of Posidonia oceanica seagrass meadows display considerable trophic diversity
Michel, Loïc ULg; Dauby, Patrick ULg; Gobert, Sylvie ULg et al

in Marine Ecology (in press)

Gut content examination and trophic markers (fatty acids, stables isotopes of C and N) were combined to delineate the diet of the dominant species of amphipods from Mediterranean Posidonia oceanica ... [more ▼]

Gut content examination and trophic markers (fatty acids, stables isotopes of C and N) were combined to delineate the diet of the dominant species of amphipods from Mediterranean Posidonia oceanica seagrass meadows and to highlight trophic diversity among this community. Our results indicate that, although all dominant species heavily relied on macroalgal epiphytes, considerable interspecific dietary differences existed. Carbon stable isotope ratios notably showed that some of the amphipod species favored grazing on epiphytes from leaves or litter fragments (Apherusa chiereghinii, Aora spinicornis, Gammarus aequicauda), while others like Dexamine spiniventris preferred epiphytes from rhizomes. The remaining amphipods (Caprella acanthifera, Ampithoe helleri and Gammarella fucicola) readily consumed both groups. In addition, SIAR modeling suggested that most species had a mixed diet, and relied on several food items. Fatty acid analysis and gut contents revealed that contribution of microepiphytic diatoms and of benthic and suspended particulate organic matter to the diet of amphipods were anecdotal. None of the examined species seemed to graze on their seagrass host (low 18:2(n-6) and 18:3(n-3) fatty acids contents), but G. aequicauda partly relied on seagrass leaf detritus, as demonstrated by the lesser 13C-depletion of their tissues. Overall, our findings suggest that amphipods, because of their importance in transfers of organic matter from primary producers and detritus to higher rank consumers, are key-items in P. oceanica associated food webs. [less ▲]

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See detailAn ecological study of Electra posidoniae Gautier, 1954 (Cheilostomata, Anasca), a bryozoan epiphyte solely found on the seagrass Posidonia oceanica (L.) Delile, 1813
Lepoint, Gilles ULg; Mouchette, Olivier; Pelaprat, Corine et al

in Belgian Journal of Zoology (in press)

The bryozoan Electra posidoniae Gautier is found solely on the leaves of the Neptune grass Posidonia oceanica (L.) Delile, dominating the leaf epifauna of this seagrass. Epiphytes of marine angiosperms ... [more ▼]

The bryozoan Electra posidoniae Gautier is found solely on the leaves of the Neptune grass Posidonia oceanica (L.) Delile, dominating the leaf epifauna of this seagrass. Epiphytes of marine angiosperms (or seagrasses) often play an important role in ecosystem functioning, for example as food web suppliers. As dysfunction of epiphytic compartment is often implied in human-induced seagrass decline, it is important to understand the dynamics and life traits of this community in pristine areas. This study involved the monthly assessment of colonization dynamics, biomass seasonality and diet composition through stable isotopes measurements of E. posidoniae at a depth of 10 m in the Revellata Bay (Corsica, Mediterranean Sea). Ancestrulae (i.e. colony founders) appeared towards the end of winter and were very selective in their settlement position along the P. oceanica leaves. A maximum of 100,000 colonies per square meter was recorded. E. posidoniae colonies dominated the epiphytic community biomass in early spring, and were over-covered by epiphytic algae in June. Food shortage could be also involved in this decrease. Although stable isotope ratios of C, N and S showed that this suspension feeder mainly relies on the water column productivity for its food, other food sources such as re-suspended epiphytic diatoms could be important in late spring (i.e. after the phytoplanktonic bloom). Additionally, a contribution of seagrass phytodetritus to the diet of this species cannot be excluded. The species was almost absent in winter, raising the question of its recruitment in spring. This study confirms the quantitative importance of this species in the seagrass meadow and explores its role in the relationship between the water column and this seagrass ecosystem. [less ▲]

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See detailMultiscale variability of amphipod assemblages in Posidonia oceanica meadows
Sturaro, Nicolas ULg; Lepoint, Gilles ULg; Vermeulen, Simon et al

in Journal of Sea Research (in press)

The study of spatial patterns is of ecological importance in order to understand the causes of the distribution and abundance of organisms, and it also provides valuable basis for management and ... [more ▼]

The study of spatial patterns is of ecological importance in order to understand the causes of the distribution and abundance of organisms, and it also provides valuable basis for management and conservation. Amphipod crustaceans are key organisms in seagrass ecosystems. However, little attention has been paid to the spatial scales at which amphipod assemblages may vary. We examined variability patterns of amphipod populations inhabiting Posidonia oceanica meadows, over spatial scales spanning four orders of magnitude (1 to 1000 metres) and for two consecutive years. This study reports the scales that contributed most to spatial variation of amphipod assemblages and explores the potential processes of the observed patterns, with particular emphasis on habitat features. The number of species, the diversity and the density of some species, exhibited high variation across years. Most species showed the highest spatial variation in density and biomass at small scales (~1 and 10 m). Based on density data, the structure of amphipod assemblages did not differ at any scales investigated. The patchiness that occurred at small scales may have been only weakly related to habitat features. Instead, we postulated that behavioural processes of amphipods were likely good explanatory factors. Although, the small scale spatial variability can be an important feature of amphipod assemblages in P. oceanica meadows, many patterns probably remained undetected as they may occur at scales smaller than those investigated. [less ▲]

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See detailIslands as reference stations for environmental studies: the case of Calvi Bay in Corsica
Abadie, Arnaud ULg; Gobert, Sylvie ULg; Lejeune, Pierre

Conference (2014, July 05)

Islands are subject to human activities and their impacts on land and marine ecosystems. They are also often isolated from some of the continental influences but on the other hand different kind of human ... [more ▼]

Islands are subject to human activities and their impacts on land and marine ecosystems. They are also often isolated from some of the continental influences but on the other hand different kind of human activities can be concentrated in small areas. These characteristics make possible the management of many programs that use whole islands, or some of their parts, as a reference station for environmental studies. From this perspective, the program STARE-CAPMED has begun in 2012 at STARESO, an oceanographic research station established at Calvi Bay (Corsica) since the early 70’s. It aims to create a reference station for the study of emerging local and global anthropogenic impacts on marine pristine ecosystems. Several universities are involved in this project and provide their expertise in various fields of marine sciences. This program provides a precise view of the environmental processes that occur, which are strongly linked with economic and cultural issues. [less ▲]

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See detailTrace element bioaccumulation in rope-grown Mytilus galloprovincialis: knowledge update
Richir, Jonathan ULg; Gobert, Sylvie ULg

Poster (2014, May 12)

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 interindividual 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 underlined the potential use of M. galloprovincialis in the biomonitoring of numerous little studied TEs and gave 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 detailHas oxygen depletion an impact on nutrients and macrofauna in a highly dynamic macrophytodetritus accumulation?
Remy, François ULg; Mascart, Thibaud ULg; Dauby, Patrick ULg et al

Poster (2014, May 06)

Posidonia oceanica is an endemic Mediterranean highly productive seagrass. Depending on the ability of the primary consumers to digest it alive, a generally important part of its foliar primary production ... [more ▼]

Posidonia oceanica is an endemic Mediterranean highly productive seagrass. Depending on the ability of the primary consumers to digest it alive, a generally important part of its foliar primary production falls in autumn, to decay inside the meadow or to be exported to sand patches to form “exported litter accumulations”. These accumulations are highly dynamic depending on hydrodynamics and seafloor geomorphology. Literature says that low O2 conditions might occur inside litter accumulations, but the annual oxygen dynamics or its impact on the litter-associated macrofauna has never been measured. We focused on 2 exported litter accumulations in Calvi Bay (Corsica), during 2 years for a total of 8 seasons. For each season, we collected water samples (n=6) from 3 different strata: Water Column (WC), Water Just Above the litter (WJA) and Water Inside the litter (WI). Oxygen was measured for each replicate using a Winkler-based automated routine for oxygen concentration measurements on micro-volumes. At the same time, nutrients concentrations (PO4, NH4, and NO2+NO3) were measured in WC, WJA and WI, but also in the Interstitial Water (IW) using a spectrophotometric continuous flow analyzer (adapted for low nutrients level in an oligotrophic environment). In parallel, macrofaunal (size >500µm) samples (n=3-6) were also collected, counted and identified to the specific level. Our results show significant differences between O2 concentrations/saturation from WI and the two other strata. Significant differences were detected between seasons, sites and years for WI which is the only stratum where really low O2 conditions can be observed. Significant differences were also detected between seasons for both WC and WJA but no differences between sites and years. On the other hand no significant differences were detected between WC and WJA. A similar observation was made for the nutrients at the annual, seasonal and spatial level. Moreover differences are also observed between the nutrients themselves. Our data shows no correlation between WI O2 concentrations and saturation, and global macrofauna abundance or biodiversity. Results are more contrasting at an individual specific level for the 4 most dominant species. For two amphipod species, Gammarella fucicola (55% of the global abundance) and Gammarus aequicauda, no significant correlations were detected between their abundance and O2. For the leptostracan species, Nebalia strausi, a significant negative correlation with O2 concentration was detected. For the last amphipod species, Melita hergensis, a significant positive correlation was observed. Our analyses also show significant correlations between WI O2 concentration/saturation, and WI / IW nutrients concentration. To conclude, this work shows that WI is a very particular and dynamic environment considering O2 concentration and saturation. Low O2 conditions can be observed in WI but never in WC or WJA showing that internal processes and relations with the sediment determine the O2 dynamics in WI and showing a potential “barrier” effect between WI and WC. Moreover O2 dynamics and its consequences may play a role in the nutrients dynamics and cycles. It is clear that faunal responses to low O2 conditions are not identifiable at a global community level. At a specific level, we show a more complex situation: some species do not seem to be impacted by low O2 conditions, but some present a significant positive, or a significant negative response. This shows the existence and complexity of species-dependent low O2 tolerance/adaptation, and the importance of a specific level data analyses to detect responses of dominant litter associated macro- invertebrates to O2 concentration and saturation variations. [less ▲]

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See detailHypoxia in macrophytodetritus accumulation: Species specific harpacticoid copepod adaptation?
Mascart, Thibaud ULg; De Troch, Marleen; Gobert, Sylvie ULg et al

Poster (2014, May 05)

Mediterranean Posidonia oceanica seagrass meadows generate high primary production and support large biodiversity of associated fauna and flora. The majority of the foliar material falls on the ... [more ▼]

Mediterranean Posidonia oceanica seagrass meadows generate high primary production and support large biodiversity of associated fauna and flora. The majority of the foliar material falls on the unvegetated sea floor during the autumnal leaf senescence, fuelling the detrital food web. Whilst laying on the sea floor the freshly formed macrophytodetritus pile up into accumulations according to the local hydrodynamics and seafloor geomorphology. In these litter accumulations, harpacticoid copepods (Crustacea, Copepoda) are the main meiofaunal players (metazoans in the size range of 38µm – 1mm) and show a high specific diversity. They are primarily grazers, but their high specific diversity suggests that they occupy also a large variety of trophic niches. This large morphological and trophic diversity can partly be promoted by the complexity of the phytodetritus in seagrass accumulations. On the other hand, macrophytodetritus degradation and flux of reduced compounds from the sediments is responsible for oxygen consumption inside the accumulation of seagrass litter. Therefore, concentration of oxygen inside the accumulation is very variable and often under the concentration observed in the water column just above the litter. Frequently, oxygen levels reach very low values. The present study aims to link the oxygen variability inside the accumulation to the densities of the five most dominant harpacticoid copepods found living in the P. oceanica litter. Standardized samples were collected seasonally in two contrasting sites of the Calvi Bay (Corsica) during one year. Our results showed no correlation between the oxygen concentrations and harpacticoid community diversity or their total abundances. The five most dominant species showed divergent results, but none had a clear correlation with the oxygen concentration. This contrasts with observation done for sediment meiofaunal community where most harpacticoid copepods are sensitive to oxygen level and where nematodes often dominate the community. This could be explained by their high mobility and the patchiness and variability of the oxygen concentrations present in the accumulations. Harpacticoid copepods, whilst being sensitive to hypoxia and anoxia developed a strategy to live in this fast oxygen changing environment. To conclude, our results underline the importance of species-specific analysis of correlation data. Especially in complex and dynamic environments where a variety of potential trophic niches are present and species competition is very likely to occur. The overall abundance pattern and diversity of the copepod community showed no relation to the oxygen concentration while the most abundant copepod species did not responded to fluctuating oxygen concentrations. [less ▲]

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See detailSEDIMENTS OXIDATION BY SEAGRASSES: INFLUENCE ON THE S CYCLE IN POSIDONIA OCEANICA (L.) DELILE INTERMATTES DYNAMIC
Abadie, Arnaud ULg; Lejeune, Pierre; Pergent, Gérard et al

Poster (2014, May)

The Mediterranean seagrass Posidonia oceanica forms meadows and develops a complex of rhizomes, roots and sediment which is called “matte”. P. oceanica meadows show discontinuity patterns in the form of ... [more ▼]

The Mediterranean seagrass Posidonia oceanica forms meadows and develops a complex of rhizomes, roots and sediment which is called “matte”. P. oceanica meadows show discontinuity patterns in the form of sand or dead matte (matte without living shoots) patches, called “intermattes”, which can have natural or anthropogenic origins. Mechanical processes (e. g. currents, anchoring) can initiate intermattes formation but their dynamic after creation seems to be linked with the sediment chemistry, especially with S cycle. P. oceanica plays an important role in controlling coastal belowground biogeochemistry, in particular by oxidizing sediments through the release of O2 by roots. This process allows creating more suitable condition for plant growth and colonization. The lack of H2S oxidation in SO4 2- can lead to limitation of the plant development or its regression. In order to investigate the effect of oxidation condition in sediments on intermattes dynamic and the neighboring meadow, we initiate, in December 2013, a study on six intermattes (three natural, three anthropogenic) at different depths in Calvi Bay, in Corsica (France). We hypothesize that redox potential and H2S concentration in sediments play an important role in the regression of P. oceanica meadows, particularly after a mechanical anthropic impact like anchoring. It also may be possible that two different kinds of processes are involved for each type of intermatte. Regular samplings throughout two years are planed with the aim of evaluating the seasonal variations of physicochemical parameters. [less ▲]

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See detailCorsican seagrass detritus: An opportune shelter or a copepod Eldorado?
Mascart, Thibaud ULg; Lepoint, Gilles ULg; Remy, François ULg et al

Poster (2014, March 07)

Seagrass ecosystems are extensive beds of marine flowering plants bordering tropical and temperate coastal regions. They play an important role in maintaining biological productivity and bio-geochemical ... [more ▼]

Seagrass ecosystems are extensive beds of marine flowering plants bordering tropical and temperate coastal regions. They play an important role in maintaining biological productivity and bio-geochemical cycles in the sea and support higher diversity and abundance of fauna in comparison to adjacent non-vegetated areas. The seagrass meadow primary production can be directly consumed through herbivory but the majority of the plant material falls on the sea floor during the autumnal leaf senescence. The leaf litter then degrades within the meadow or accumulates with other micro- and macrophytodetritus to form detritus accumulations on the adjacent non-vegetated sand patches. These exported accumulations are quite dynamic in relation to seafloor geomorphology and local hydrodynamics. Thus, the detritus accumulations are an easily disturbed ephemeral environment with one large influx a year. Consequently the physico-chemical characteristics can change very fast and impact the sheltering capacity and food supply present. Nonetheless, fishes, macrofauna and meiofauna are omnipresent throughout the year. In our study site along the shore of N-W Corsica, Posidonia oceanica seagrass meadows are characterised by substantial detritus accumulations. The present study aimed to analyse the biodiversity of the copepod species communities (Crustacea, Copepoda) in those detritus accumulations. The results showed that the copepod detritus community consisted of a mixture of species that are also found in adjacent habitats (seagrass meadow, sediment, epilithic habitats, water column). Each adjacent habitat is characterised by organisms that are morphologically adapted to the specific features of that habitat. The majority of copepods are epiphytic (order Harpacticoida), that occur typically on seagrass leaves and macroalgae. Other species are planktonic (orders Cyclopoida and Calanoida) and some were benthic (order Harpacticoida), known from the nearby sediment. A minority of the copepod community were parasitic on fish or invertebrate (order Siphonostomatoida). In order to clarify their origin, we assume that passive transport by currents plays a significant role next to the active migration from the anoxic sediments under the detritus. For sure they also reproduce within the detritus packages as we found many nauplii, copepodites and gravid females. The above mentioned suggestions cannot explain such high density of copepods by themselves. Other attraction mechanisms are needed to explain the important amount of planktonic and epiphytic species with good swimming ability, such as higher food accessibility. In the detritus no plant-defence mechanisms are present anymore and a lot of micro-organisms and thus potential food sources are present. Furthermore, the dense detritus package provides shelter and protection from potential predators. Subsequently we may consider the detritus accumulations as a copepod species-specific opportune Eldorado for sheltering, nursing and feeding. [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 detailSeagrass amphipod assemblages in a Mediterranean marine protected area: a multiscale approach
Sturaro, Nicolas ULg; Lepoint, Gilles ULg; Pérez-Perera, Amanda et al

in Marine Ecology. Progress Series (2014), 506

Marine protected areas (MPAs) are a key tool for conservation purposes, but few studies have assessed the responses of small macrozoobenthic assemblages to different protection levels in the Mediterranean ... [more ▼]

Marine protected areas (MPAs) are a key tool for conservation purposes, but few studies have assessed the responses of small macrozoobenthic assemblages to different protection levels in the Mediterranean Sea. In this study, we used a hierarchical sampling design spanning three orders of magnitude (1-10-100 metres) to investigate whether a marine protected area exerts an effect on amphipod assemblages associated with Posidonia oceanica meadows. This study reports spatial and temporal variability patterns of amphipod assemblages in four different protection levels and discusses potential confounding effects, such as habitat features. The structure of amphipod assemblages based on density data was patchy at all spatial scales investigated, but differed markedly among protection levels. Among outstanding points, multiscale analyses showed that lower densities and/or biomasses of several taxa occurred within fully protected and external areas in comparison with partially protected areas (PPAs). Furthermore, Posidonia oceanica meadow features (shoot density, leaf and epiphyte biomasses, coefficient A and litter biomass) accounted for only a low proportion of the total variability. We can consequently infer that the observed patchiness is likely to occur for multiple and interconnected reasons, ranging from the ecological and behavioural traits of amphipod species to protection-dependent processes (e.g. fish predation). Long term multiscale spatial and temporal monitoring, as well as experimental manipulations, are clearly needed to fully understand the effects of protection on macrozoobenthic assemblages. [less ▲]

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See detailDifferential cadmium and zinc distribution in relation to their physiological impact in the leaves of the accumulating Zygophyllum fabago L
LEFÈVRE, Isabelle; VOGEL‐MIKUŠ, Katarina; JEROMEL, Luka et al

in Plant, cell & environment (2014), 37(6), 1299-1320

Cadmium and zinc share many similar physiochemical properties, but their compartmentation, complexation and impact on other mineral element distribution in plant tissues may drastically differ. In this ... [more ▼]

Cadmium and zinc share many similar physiochemical properties, but their compartmentation, complexation and impact on other mineral element distribution in plant tissues may drastically differ. In this study, we address the impact of 10-μM Cd or 50-μM Zn treatment on ion distribution in leaves of a metallicolous population of the non-hyperaccumulating species Zygophyllum fabago at tissue and cell level, and the consequences on the plant response through a combined physiological, proteomic and metabolite approach. Micro-proton induced X-ray emission and laser ablation inductively coupled mass spectrometry analyses indicated hot spots of Cd concentrations in the vicinity of vascular bundles in response to Cd treatment, essentially bound to S-containing compounds as revealed by extended X-Ray absorption fine structure and non-protein thiol compounds analyses. A preferential accumulation of Zn occurred in vascular bundle and spongy mesophyll in response to Zn treatment, and was mainly bound to O/N-ligands. Leaf proteomics and physiological status evidenced a protection of photosynthetically active tissues and the maintenance of cell turgor through specific distribution and complexation of toxic ions, reallocation of some essential elements, synthesis of proteins involved in photosynthetic apparatus or C-metabolism, and metabolite synthesis, with some specificities regarding the considered heavy metal treatment. [less ▲]

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See detailThe Seascape as an Indicator of Environmental Interest and Quality of the Mediterranean Benthos: The in Situ Development of a Description Index: The LIMA
Gobert, Sylvie ULg; Aurélia Chéry; Alexandre Volpon et al

in Musard, Olivier (Ed.) Underwater Seascape (2014)

The LIMA index conveys the environmental interest and quality of the landscape formed by the Mediterranean benthos, ranging from 0 to − 40 m, in numerical format. The LIMA index allows a comparison ... [more ▼]

The LIMA index conveys the environmental interest and quality of the landscape formed by the Mediterranean benthos, ranging from 0 to − 40 m, in numerical format. The LIMA index allows a comparison spatially and temporarily between sites. It is a comprehensive index which is easy to implement and is composed of two factors: a topographical description (classification of 15 typologies) and a biological description (the presence or absence of some thirty species or groups of structuring, remarkable and invasive species). The LIMA index has been validated in he Bay of Calvi (Corsica-France) where it varies between 0.31 and 0.79 on a scale of 0.00–1.00. [less ▲]

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See detailPhysical modelling of water, fauna and flora: knowledge gaps, avenues for future research and infrastructural needs
ROBERT, THOMAS; JOHNSON, MATTHEW; FROSTICK, LYNNE et al

in Journal of Hydraulic Research (2014), 52

Physical modelling is a key tool for generating understanding of the complex interactions between aquatic organisms and hydraulics, which is important for management of aquatic environments under ... [more ▼]

Physical modelling is a key tool for generating understanding of the complex interactions between aquatic organisms and hydraulics, which is important for management of aquatic environments under environmental change and our ability to exploit ecosystem services. Many aspects of this field remain poorly understood and the use of physical models within eco-hydraulics requires advancement in methodological application and substantive understanding. This paper presents a review of the emergent themes from a workshop tasked with identifying the future infrastructure requirements of the next generation of eco-hydraulics researchers. The identified themes are: abiotic factors, adaptation, complexity and feedback, variation, and scale and scaling. The paper examines these themes and identifies how progress on each of them is key to existing and future eðorts to progress our knowledge of eco-hydraulic interactions. Examples are drawn from studies on biofilms, plants, and sessile and mobile fauna in shallow water fluvial and marine environments. Examples of research gaps and directions for educational, infrastructural and technological advance are also presented. [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 detailSeasonal and depth-related biodiversity of leaf epiphytic Cheilostome Bryozoa in a Mediterranean Posidonia oceanica meadow
Lepoint, Gilles ULg; Balancier, Boris; Gobert, Sylvie ULg

in Cahiers de Biologie Marine (2014), 55(1),

: Epiphytes living fixed on Posidonia oceanica L. (Delile) are important faunal and floral components of seagrass meadow ecosystems. They are involved as main actors in trophic web and major ecosystem ... [more ▼]

: Epiphytes living fixed on Posidonia oceanica L. (Delile) are important faunal and floral components of seagrass meadow ecosystems. They are involved as main actors in trophic web and major ecosystem processes of this endangered coastal habitat. This paper aims to assess the seasonality and the bathymetric variability of epiphytic Bryozoa which are the most important animal group in terms of both diversity and abundance living on P. oceanica leaves. Posidonia shoots were collected from the Revellata Bay (Corsica, France) in four seasons from 7 to 30 m depth. Colony densities reached more than 87000 colonies. m-2 at 10 m depth in spring. The bryozoan species distribution and abundance changed substantially according to seasons and depths, being maximum in spring and minimal in winter. Dominant colony morphotypes change according to depth, probably in relation with water motion gradient. This confirms that there are bathymetric and seasonal variability for different epiphytic organisms colonizing the Posidonia leaves. This enlightens the importance to protect Posidonia meadow on its full depth extension and in its connectivity with other habitats to conserve optimal epiphytic biodiversity and functions. [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 detailRecent advances in the biomonitoring of trace elements using P. oceanica (L.) Delile
Gobert, Sylvie ULg; Richir, Jonathan ULg

in de Lange, Gert J.; Gacic, Miroslav; Romaña, Axel (Eds.) et al 40th CIESM Congress Proceedings (2013, November)

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 detailProtection effects or natural variability? The case of seagrass amphipods
Sturaro, Nicolas ULg; Lepoint, Gilles ULg; Pérez-Perera, Amanda et al

Conference (2013, October)

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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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