References of "Gobert, Sylvie"
     in
Bookmark and Share    
Full Text
See detailApplication of stable isotopes in trophic ecology: importance of TEF and seasonal baseline for robust interpretations.
Remy, François ULg; Darchambeau, François ULg; Dauby, Patrick ULg et al

Conference (2015, April 02)

Nitrogen, carbon and sulfur stable isotopes are very powerful tools for trophic ecologists to delineate food webs of various ecosystems. More recently… the use of mixing models has exponentially increased ... [more ▼]

Nitrogen, carbon and sulfur stable isotopes are very powerful tools for trophic ecologists to delineate food webs of various ecosystems. More recently… the use of mixing models has exponentially increased to give a more specific vision of organism’s diets and trophic relationships. Two case studies will be presented to give a summary of what’s been done in Liège Oceanology Lab to improve our interpretation of stable isotopes results. First is an experimental calculation of the Trophic Enrichment Factors (TEFs) for one dominant detritivorous species of Mediterranean amphipod inhabiting seagrass detritus: Gammarus aequicauda (Martynov, 1931). This experimental study was planned after a strange result of the SAIR mixing model, giving results opposed to all observations and knowledge we had about this species. Thus, the impact of 3 very different food sources (amphipod powder, algae power, seagrass powder) on the turnover rate of C and N isotopic compositions was tested, and afterwards TEFs for C and N for each source were calculated. Animal food source showed to be the most effectively assimilated with a fast turnover rate while seagrass and algae showed very slow assimilation. TEFs calculations showed to be interesting because TEFs seem not to depend on the natural feeding type of the invertebrate but more on the type of food source. Animal source showed carnivorous TEFs values while seagrass and algae source showed typical detritivorous values. SIAR results with these new custom values gave more coherent values highlighting the major importance of TEFs values for mixing models data interpretation. Second is a simple question: are the seasonal isotopic composition variations observed for many seagrass detritus macrofauna species due to actual diet changes, or only to isotopic baseline shift of the food sources? Macrofauna and all potential food sources were sampled near STARESO Oceanographic Station (Corsica, 8°45’E; 42°35’N) in 2011-2012 at each season at two different sites. SIBER software runs with C and N isotopic data showed spatio-temporal isotopic variations at community, interspecific and intraspecific level. SIBER did not gave us information about the origin of these changes, but coupled with SIAR and our custom TEFs, species actually showing drastic changes of diet were identified, while others seem to reflect more a source baseline isotopic composition shift. Working at specific level is compulsory for fine conclusions. These two case studies highlight the importance of mixing model use and of accurate TEF values to run these models properly to draw robust and reliable conclusions using stable isotopic data. [less ▲]

Detailed reference viewed: 160 (7 ULg)
Full Text
See detailApplications of stable isotopes in environmental studies at the University of Liege
Sturaro, Nicolas ULg; Borges, Alberto ULg; Das, Krishna ULg et al

Poster (2015, March 26)

Measurement and use of stable isotope ratios have a long history at the University of Liege (Belgium). Since at least 30 years, applications of stable isotopes in marine ecosystems have been developed ... [more ▼]

Measurement and use of stable isotope ratios have a long history at the University of Liege (Belgium). Since at least 30 years, applications of stable isotopes in marine ecosystems have been developed within the Laboratory of Oceanology and, more recently, within the Chemical Oceanography Unit. In the Laboratory of Oceanology, one research axis is the measurement of stable isotope composition (C, N, S) in organic matter to delineate trophic web structure and to study animal diet, their trophic niches and their alteration by human activities. This methodology has been successively applied worldwide in different habitats and ecosystems (marine, freshwater, terrestrial) in temperate and tropical areas. Mediterranean food web and fish trophic ecology have received a particular attention. Coupling between trophic ecology and ecotoxicology is another area of investigation. This has been applied mainly to marine vertebrates and freshwater ecosystems. Stable isotope labelling is also used in our laboratory to study and quantify various ecological processes such as inorganic nitrogen incorporation and trophic transfers. The laboratory facilities, renewed in 2012 and managed by Dr. Gilles Lepoint, are composed of an elemental analyser (EA, vario MICRO cube, Elementar) and a gas chromatography (GC, Agilent) coupled to an isotope ratio mass spectrometer (IRMS, Isoprime 100). The GC is also equipped with a quadrupole mass spectrometer. In 2014, the Chemical Oceanography Unit, headed by Dr. Alberto Borges, has acquired and implemented an off-axis cavity ring-down spectroscopy (CRDS) for the measurements of δ15Nα, δ15Nβ, δ18O of N2O. This enables characterization of the N2O origin in a variety of aquatic environments including groundwater in Wallonia, rivers and lakes in Wallonia and Africa, coastal environments (Scheldt estuary, Lake Grevelingen, North Sea), Mediterranean seagrass beds, and Antarctic and Arctic sea-ice. [less ▲]

Detailed reference viewed: 105 (13 ULg)
Full Text
Peer Reviewed
See detailBioassessment of trace element contamination of Mediterranean coastal waters using the seagrass Posidonia oceanica
Richir, Jonathan ULg; Salivas-Decaux, Maÿlis; Lafabrie, Céline et al

in Journal of Environmental Management (2015), 150

A large scale survey of the trace element (TE) contamination of Mediterranean coastal waters was performed from the analysis of Ag, As, Cd, Cu, Hg, Ni and Pb in the bioindicator Posidonia oceanica ... [more ▼]

A large scale survey of the trace element (TE) contamination of Mediterranean coastal waters was performed from the analysis of Ag, As, Cd, Cu, Hg, Ni and Pb in the bioindicator Posidonia oceanica, sampled at 110 sites differing by their levels of exposure to contaminants. The holistic approach developed in this study, based on the combined utilization of several complementary monitoring tools, i.e. water quality scale, pollution index and spatial analysis, accurately assessed the TE contamination rate of Mediterranean coastal waters. In particular, the mapping of the TE contamination according to a new proposed 5-level water quality scale precisely outlined the contamination severity along Mediterranean coasts and facilitated interregional comparisons. Finally, the reliability of the use of P. oceanica as bioindicator species was again demonstrated through several global, regional and local detailed case studies. NB: The designations employed and the presentation of the information in thisdocument do not imply the expression of any opinion whatsoever on the part of the authors concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. [less ▲]

Detailed reference viewed: 135 (36 ULg)
Full Text
Peer Reviewed
See detailEarly colonization on Artificial Seagrass Units and on Posidonia oceanica (L.) Delile leaves
Pete, Dorothée ULg; Lepoint, Gilles ULg; Bouquegneau, Jean-Marie ULg et al

in Belgian Journal of Zoology (2015), 145(1), 59-68

Many epiphytes grow on Posidonia oceanica (L.) Delile leaves but early stages of that colonization are not well known. To study this early colonization without destroying the plant, Artificial Seagrass ... [more ▼]

Many epiphytes grow on Posidonia oceanica (L.) Delile leaves but early stages of that colonization are not well known. To study this early colonization without destroying the plant, Artificial Seagrass Units (ASUs) were utilised. The first nine days of colonization by macroscopic eukaryotic organisms on natural P. oceanica leaves and on ASUs were studied. The capability of those ASUs to mimic P. oceanica in the long term was also evaluated. Indeed, early colonists of a substrate can influence the settling of later ones by “priority effects”. Thus if the pioneer community is the same on both substrates, they will more likely be the same after a longer exposure time. On both substrates, colonization began by the settling of crustose-calcareous algae and foraminiferans. The number of organisms increased more quickly on ASUs than on natural leaves but Shannon-Wiener diversity index was higher for P. oceanica leaves. The low colonization rate on natural leaves may have been due to different microclimatic conditions on the two substrates and to a less developed biofilm than on ASUs. The high diversity observed on natural leaves was mainly related to the presence of bryozoan ancestrulae, which were absent on ASUs. Different microhabitats on each substrate (different algae morphotypes) can explain this difference. Thus, at such an early colonization stage, pioneer communities were different on the two substrates, suggesting that later communities would be different too. However, ASUs could be used in environmental perturbation studies instead of natural leaves, thanks to their high colonization rate. [less ▲]

Detailed reference viewed: 56 (6 ULg)
Full Text
Peer Reviewed
See detailMarine space ecology and seagrasses. Does patch type matter in Posidonia oceanica seascapes?
Abadie, Arnaud ULg; Gobert, Sylvie ULg; Bonacorsi, Marina et al

in Ecological Indicators (2015), 57

The use of landscape tools in the study of seagrass meadows (seascapes) begins to be widely spreadbut still require the establishment of several basis, i.e. a patch type classification based on ... [more ▼]

The use of landscape tools in the study of seagrass meadows (seascapes) begins to be widely spreadbut still require the establishment of several basis, i.e. a patch type classification based on numericalcharacteristics. Thanks to the complex seascapes created by the Posidonia oceanica meadows, they appearto be suitable for a study at a patch type level (class), which bring a new insight of their arrangement at thewhole seascape scale. By interpreting side scan sonar images from the Corsican coast (France) through aGIS software, it was possible to describe 11 types of patches and to evaluate their natural or anthropogenicorigin. Comparison of different landscape metrics and wave exposure (Relative wave Exposure Index,REI) at the seascape and the patch level showed that the particularity of P. oceanica seascapes are mainlycharacterized by certain types of patches often of anthropogenic origin. Furthermore the REI seems not tobe a relevant index for a study at a class scale. A bathymetrical succession of natural patches was outlinedfrom the lower to the upper limit of the meadow, with a long-term dynamic opposed to a shorter oneconcerning anthropogenic patches. In order to assess the origin (natural or induced by human activities)of the patches in P. oceanica meadows, as well as in any other seagrass, a Patchiness Source Index (PaSI),ranging from 0 to 1, was defined. [less ▲]

Detailed reference viewed: 44 (18 ULg)
Full Text
Peer Reviewed
See detailTowards a framework for assessment and management of cumulative human impacts on marine food webs
Giakoumi, Sylvaine; Halpern, Benjamin S.; Michel, Loïc ULg et al

in Conservation Biology (2015), 29(4), 1228-1234

Effective ecosystem-based management requires understanding ecosystem responses to multiple human threats, rather than focusing on single threats. To understand ecosystem responses to anthropogenic ... [more ▼]

Effective ecosystem-based management requires understanding ecosystem responses to multiple human threats, rather than focusing on single threats. To understand ecosystem responses to anthropogenic threats holistically, it is necessary to know how threats affect different components within ecosystems and ultimately alter ecosystem functioning. We used a case study of a Mediterranean seagrass (Posidonia oceanica) food web and expert knowledge elicitation in an application of the initial steps of a framework for assessment of cumulative human impacts on food webs. We produced a conceptual seagrass food web model, determined the main trophic relationships, identified the main threats to the food web components, and assessed the components’ vulnerability to those threats. Some threats had high (e.g., coastal infrastructure) or low impacts (e.g., agricultural runoff) on all food web components, whereas others (e.g., introduced carnivores) had very different impacts on each component. Partitioning the ecosystem into its components enabled us to identify threats previously overlooked and to reevaluate the importance of threats commonly perceived as major. By incorporating this understanding of system vulnerability with data on changes in the state of each threat (e.g., decreasing domestic pollution and increasing fishing) into a food web model, managers may be better able to estimate and predict cumulative human impacts on ecosystems and to prioritize conservation actions. [less ▲]

Detailed reference viewed: 78 (31 ULg)
Full Text
Peer Reviewed
See detailA consensual Diving-PAM protocol to monitor Posidonia oceanica photosynthesis
Gobert, Sylvie ULg; Lepoint, Gilles ULg; Silva, João et al

in PeerJ (2015)

The seagrass Posidonia oceanica is widely recognized as an effective bioindicator of the health status of Mediterranean coastal waters. Chlorophyll fluorescence measurements, in particular through the ... [more ▼]

The seagrass Posidonia oceanica is widely recognized as an effective bioindicator of the health status of Mediterranean coastal waters. Chlorophyll fluorescence measurements, in particular through the Pulse Amplitude Modulated (PAM) fluorometry method, are performed to study aquatic plant ecology and vitality and to assess their responses to diverse stressful factors. However, the current understanding of P. oceanica photosynthetic responses to environmental stresses does only allow scientists to use the PAM-method as a complementary tool to other more-robust monitoring techniques. Consequently, a more in-depth knowledge of the natural causes of variability of P. oceanica photosynthetic responses are a prerequisite to any surveys relying on that time and cost-effective method. In the framework of the STARECAPMED project, this work aimed to determine the influence of several environmental (depth, daytime, season) and plant-specific characteristics (leaf age, leaf part analyzed, epiphytic coverage) on the photosynthetic responses (Y, ETR, RLC) of P. oceanica. Water temperature, irradiance and several biochemical parameters of the seagrass (chl.a, chl.b, C, N, P, micronutrients such as Fe, Cu) were measured as well. The field survey was performed in a pristine meadow in the Calvi Bay, Corsica. Environmental and plant-physiological characteristics deeply influenced P. oceanica photosynthetic responses. As an example, ETR decreased with depth, contrary to Y that mostly increased. ETR was lower in the basal part of leaf blade, and the epiphytic coverage of leaf tips slightly increased their ETR compared to leaf tips cleaned of epiphytes. Depth and leaf part-related variations in RLC were also observed. Because of this natural variability, it appears essential to develop a consensual protocol of chlorophyll fluorescence measurements to publish reliable and comparable results between studies. We therefore notably suggest to perform measurements close to midday, when photosynthetic responses are the highest; at 10-15 m depth in order to avoid, among others, low depth light irradiance variability; on the middle part of the 3rd-4th external leaf, well developed, highly photosynthetic, and little epiphyted. Finally, because P. oceanica fluorescence was correlated with N, P and chl.b leaf contents, the PAM-method could afterwards be used as bioindicator technique, according to the protocol proposed. [less ▲]

Detailed reference viewed: 50 (12 ULg)
Full Text
Peer Reviewed
See detailAcoustic monitoring of O2 production of a seagrass meadow
Felisberto, Paulo; Jesus, Sérgio M.; Zabel, Friedrich et al

in Journal of Experimental Marine Biology and Ecology (2015), 464(0), 75-87

Acoustic data were acquired in October 2011 over a Posidonia oceanica meadow in the Bay of la Revellata, Calvi, Corsica. The purpose was to develop an acoustic system for monitoring the oxygen (O2 ... [more ▼]

Acoustic data were acquired in October 2011 over a Posidonia oceanica meadow in the Bay of la Revellata, Calvi, Corsica. The purpose was to develop an acoustic system for monitoring the oxygen (O2) production of an entire seagrass meadow. In a shallow water area (b38 m), densely covered by P. oceanica, a sound source transmitted signals in 3 different bands (400–800 Hz, 1.5–3.5 kHz and 6.5–8.5 kHz) toward three self-recording hydrophones at a distance of 100 m, over the period of oneweek. The data showa high correlation between the diel cycle of the acoustic signals' energy received by the hydrophones and the temporal changes in water column O2 concentration as measured by optodes. The results thus show that a simple acoustic acquisition system can be used to monitor the O2-based productivity of a seagrass meadow at the ecosystem level with high temporal resolution. The finding of a significant production of O2 as bubbles in seagrass ecosystems suggests that net primary production is underestimated by methods that rely on the mass balance of dissolved O2 measurements. [less ▲]

Detailed reference viewed: 103 (33 ULg)
Full Text
Peer Reviewed
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 (2015), 95

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 ▲]

Detailed reference viewed: 95 (44 ULg)
Full Text
See detailAre amphipods influenced by Posidonia oceanica seagrass features?
Sturaro, Nicolas ULg; Lepoint, Gilles ULg; Michel, Loïc ULg et al

Poster (2014, December 12)

In the Mediterranean Sea, the seagrass Posidonia oceanica plays an important role as habitat for invertebrates, among which amphipod crustaceans represent a dense and diverse assemblage. Recent studies ... [more ▼]

In the Mediterranean Sea, the seagrass Posidonia oceanica plays an important role as habitat for invertebrates, among which amphipod crustaceans represent a dense and diverse assemblage. Recent studies have observed that amphipod density and biomass vary significantly on small spatial scales. This patchiness may be caused by different factors, such as recruitment, competition, and predation; however, habitat features, resulting in availability of resources such as food or shelter, may also be important in structuring these assemblages. This study examined the relationships between amphipod and habitat features in a P. oceanica meadow of the Revellata Bay (Corsica). The sampling was carried out in a continuous meadow colonizing soft substrates at constant depth in August 2008. We quantified the density and biomass of each amphipod species, as well as habitat features, namely shoot density, leaf and epiphyte biomasses, percentage of leaves per shoot having alteration marks and litter biomass. Using multiple regression analyses, few weak significant relationships were identified between amphipod and habitat features. The number of species and the diversity appeared unaffected by the measured habitat features. In contrast, total amphipod density and biomass were generally positively related to the shoot density and epiphyte biomass of P. oceanica, respectively. Overall, habitat features accounted for 0-30% of the variation in the densities of the amphipod species. A distance-based linear model explained a total of 25.8% of the variation of the amphipod assemblages (of which 18.6% was explained by litter biomass). Amphipods are therefore influenced by some P. oceanica features, but only weakly. Furthermore, some features appeared to influence individual species whereas others functioned at the assemblage level. The main challenge remains in evaluating the scale at which these features act and the way in which they influence the structure of assemblages. [less ▲]

Detailed reference viewed: 40 (2 ULg)
Full Text
See detailSeasonal sampling and stable isotopes use to delineate seagrass phytodetritus macrofauna trophic ecology: baseline variation or actual diet change?
Remy, François ULg; Mascart, Thibaud ULg; Dauby, Patrick ULg et al

Conference (2014, December 12)

In Mediterranean exported seagrass macrophytodetritus accumulations, a diverse (more than 130 species) and abundant (up to 4900 id.m-2) macrofauna assemblage is found alongside meiofauna, microalgae ... [more ▼]

In Mediterranean exported seagrass macrophytodetritus accumulations, a diverse (more than 130 species) and abundant (up to 4900 id.m-2) macrofauna assemblage is found alongside meiofauna, microalgae, fungi and bacteria. Macrophytodetritus are mainly composed of poorly digestible yet highly colonized material: the dead leaves of the very productive (300 to 2000 g dry wt m-2 yr-1) endemic seagrass Posidonia oceanica. A key role may be played by macrofauna, and more particularly by litter vagile macroinvertebrates (invertebrates > 500µm), in the degradation, enrichment and carbon transfer from P. oceanica to coastal food webs. Indeed, results of gut content observations of the most abundant species show that even if only a few of these species ingest a large proportion of P.oceanica dead leaves fragments, most of the others ingest a small but non-negligible part, suggesting a potential role of the whole community in the mechanical fragmentation of the dead leaves. Mediterranean exported macrophytodetritus accumulations are very dynamic habitats with very variable food availability, quality, and composition. Such an inconstant habitat may result in drastic modifications of the invertebrate community but also of its trophic structure and ecology. To test this hypothesis of influence of pulsed availability, quality and composition of food sources on the vagile macrofauna diet, we took seasonal samples in Calvi Bay (Corsica, 8°45’E; 42°35’N), at two sites between August 2011 and May 2012. Gut content observations and C/N/S stable isotope analysis of bulk tissues were conducted on both the macrofauna and their potential food sources. Significant seasonal and spatial differences of ingestion patterns of the most abundant species were emphasised as were differences of isotopic signatures. “SIAR” Bayesian mixing model and “SIBER” package were used to analyse isotopic data and determine if these differences were due to actual diet modifications or only to baselines isotopic composition variations. [less ▲]

Detailed reference viewed: 70 (8 ULg)
Full Text
Peer Reviewed
See detailTrace element kinetics in caged Mytilus galloprovincialis
Richir, Jonathan ULg; Lepoint, Gilles ULg; Donnay, Annick et al

Poster (2014, December)

Trace elements (TEs) remain contaminants of concern because of their persistence, ability to concentrate in organisms and toxicity. The Mediterranean mussel Mytilus galloprovincialis Lamarck, 1819 is a ... [more ▼]

Trace elements (TEs) remain contaminants of concern because of their persistence, ability to concentrate in organisms and toxicity. The Mediterranean mussel Mytilus galloprovincialis Lamarck, 1819 is a relevant bioindicator of TE coastal contamination. However, little research has studied the combined influence of environmental condition changes and physiological processes on their kinetics in that species. Caged M. galloprovincialis were thus immerged in 2 contrasted pristine Corsican (France) coastal environments, the semi-enclosed Diane salty pond and the open Calvi Bay, from February to June 2011. Mussels were regularly sampled to study the kinetics of 19 TEs in their flesh; dissolved and particulate TEs were also monitored. The primary production and the water physico-chemical variables were measured, and meteorological data were purchased from Météo-France. TE kinetics in mussels differed between sites. Mussel spawning, a temperature and saline-induced physiological process that occurred about 10 days later in the Diane pond, was followed by a short time increase of TE levels in the mussel flesh. Mussel contamination also evolved according to changes of their respective environmental TE levels. Raining events temporary led, in the Diane pond, to the water enrichment with TEs, nutrients and detrital material, to peaks of primary production and to the increase of TE concentrations in the mussel flesh. This step by step evolution of TE levels in the environment and mussels was afterwards followed by a rapid return to initial conditions. In the open Calvi Bay, these fast and balanced kinetics were not so obvious, because of the rapid dilution of environmental constrain effects in the Bay. Mussels are often used as bioindicator in estuaries and coastal enclosed meadows with rapidly changing environmental conditions. In such conditions, the influence of the environment on TE kinetics in mussels must be considered, in addition to physiological processes, when monitoring the TE coastal contamination. [less ▲]

Detailed reference viewed: 69 (14 ULg)
Full Text
Peer Reviewed
See detailTaxonomic sufficiency for soft-bottom macrozoobenthos long term study - A case study in corsica
Donnay, Annick ULg; Pelaprat, Corinne; Lejeune, Pierre et al

Poster (2014, December)

Nowadays, the knowledge of the marine ecological quality status of an environment is essential and soft-bottom macrobenthos is one of the indicators used. Studies of soft-bottom macrobenthos are time ... [more ▼]

Nowadays, the knowledge of the marine ecological quality status of an environment is essential and soft-bottom macrobenthos is one of the indicators used. Studies of soft-bottom macrobenthos are time consuming and need expertise for organisms’ identification. Simplifications of these studies are tried and Taxonomic Sufficiency (TS) proposed by Ellis (1985) is one of research axes. For example, some studies highlight that family level identification could be sufficient to identify perturbed area (e.g: Bacci et al., 2009; De-La-Ossa-Carretero et al., 2012; Forde et al., 2013). Nevertheless, identification at species level could be recommended to have more precise information about the existing situation (Ajmal Khan, 2006) or to complete information from others levels (Conde et al., 2013). In Corsican waters where human impacts are less important than in main land waters, we present TS based on STARESO research studies between 2006 and 2012. This work is within the frameworks of the STARE-CAPMED program dedicated to STAtion of Reference and rEsearch on Change of local and global Anthropogenic Pressures on Mediterranean Ecosystem Drifts. After Permanova analysis and Canonical analysis of principal coordinates, eight habitat types have been identified along Corsican coastal water. Their own reference conditions and ecological class boundaries have been evaluated. Those reference conditions and ecological status have been identified for species, genus and family level. A highly significant correlation of calculated values between species and genus levels (R²=0.93) has been determined and a significant correlation between species and family level (R²=0.75). Genus and family levels have a significant Spearman correlation with species level (p<0.05). An application of these reference conditions on the macrobenthos assemblages sampling on 14 stations in spring 2011 and late summer 2012 in Calvi Bay highlights areas with high, good or moderate ecological status. In conclusion, family level is sufficient to follow spatial and/or temporal ecological status. [less ▲]

Detailed reference viewed: 27 (0 ULg)
Full Text
See detailImpact of shading on meiofauna in a Posidonia oceanica meadow
Pete, Dorothée ULg; Gobert, Sylvie ULg

Poster (2014, December)

Posidonia oceanica meadow is an endemic ecosystem of the Mediterranean coasts. A known threat to this ecosystem is aquaculture. In zones of intensive fish production, P. oceanica meadow tends to be less ... [more ▼]

Posidonia oceanica meadow is an endemic ecosystem of the Mediterranean coasts. A known threat to this ecosystem is aquaculture. In zones of intensive fish production, P. oceanica meadow tends to be less healthy or to disappear .One of the reasons for this is a decrease in the light that reaches the leaves (direct shading, increase of water turbidity or of epiphytic algae density). Unfortunately, when the meadow begins to die, it is often too late to act. So, people are trying to find indicators that react early to this kind of perturbations. In this framework, this study focuses on the impact of shading (without nutrient enrichment) on the meiofauna living in the surface sediment of a P. oceanica meadow. An in situ shading experiment was led from the end of May to the end of August 2009, at a depth of 10 m, in a reference P. oceanica meadow. Three shading nets were put in the meadow to reach a light extinction of 50%. A control site was also defined. The first two centimetres of sampled sediment cores were studied. After three months of shading, the total abundance of meiofauna at the shading site was lower than at the beginning of the experiment, while it stayed around the same level at the control site. This difference is mainly due to a decrease in the total number of foraminiferans, nematods, gnathostomulids, copepods and bivalves. However, no significant difference in diversity was observed. At the end of this experiment, it appeared that, contrarily to what is mostly said in the literature, the direct organic enrichment that occurs at fish farms is not the only reason to the modification of the meiofauna communities of the ecosystem. The shading by itself has also an effect. [less ▲]

Detailed reference viewed: 20 (4 ULg)
Full Text
Peer Reviewed
See detailEcology of 20 trace elements in Mytilus galloprovincialis
Richir, Jonathan ULg; Lepoint, Gilles ULg; Lejeune, Pierre et al

Conference (2014, December)

Trace elements (TEs) are considered as non-degradable pollutants. This persistent character can alter their natural biogeochemical balance in contaminated environments. TEs are further toxic for aquatic ... [more ▼]

Trace elements (TEs) are considered as non-degradable pollutants. This persistent character can alter their natural biogeochemical balance in contaminated environments. TEs are further toxic for aquatic organisms from threshold levels and are thus likely to cause multiple damages to the population, the community and the ecosystem levels. For these reasons, their environmental occurrence has to be accurately monitored. The main interest of the use of quantitative sentinel organisms to this end, or bioindicator species, is their capacity to give information on the bioavailability of environmental contaminants. Mussels from the genus Mytilus are particularly well suited organisms for the monitoring of the coastal contamination. Native wild and cultured Mytilus galloprovincialis Lamarck, 1819 have been widely used since around 40 years to this purpose along coasts of the eastern Atlantic and the Mediterranean. But the accurate use of a bioindicator relies on the detailed knowledge of its ecophysiology and the influence of environmental variables on the bioaccumulation processes. In the framework of the STARECAPMED project, the ecology of 20 TEs in M. galloprovincialis is therefore investigated. The mussel morphometry and biology firstly define the TE accumulation processes. Accumulated TE are internally regulated and redistributed between body compartments; these internal processes notably depend on the essential or non-essential character of TEs. As filter feeder, mussels accumulate soluble and suspended TEs whose environmental levels are determined by the geomorphology, the physico-chemistry and the hydrology of monitored coastal meadows. All these factors are acting together to modulate the TE accumulation processes in mussels. TE bioaccumulated levels further balance quickly when any physiological or environmental changes occur in order to reach a new steady-state with environmental TE loads. The ecology of TEs in M. galloprovincialis is thus complex and very dynamic; these considerations must be taken into account when monitoring the chemical contamination of coastal meadows. [less ▲]

Detailed reference viewed: 65 (14 ULg)
Full Text
Peer Reviewed
See detailThe conceptualization of trace element flows within Posidonia oceanica meadows: a collaborative proposal to fill knowledge gaps
Richir, Jonathan ULg; Gobert, Sylvie ULg

in Langar, H.; Bouafif, C.; Ouerghi, A. (Eds.) Proceedings of the 5th Mediterranean Symposium on Marine Vegetation (2014, October)

The Mediterranean seagrass Posidonia oceanica (L.) Delile is regarded as a relevant indicator of bioavailable trace elements (TEs) since it efficiently and proportionally bioaccumulates these chemicals ... [more ▼]

The Mediterranean seagrass Posidonia oceanica (L.) Delile is regarded as a relevant indicator of bioavailable trace elements (TEs) since it efficiently and proportionally bioaccumulates these chemicals from its surrounding environment. Recent studies have further brought supplementary insights in our understanding of the processes driving TE kinetics within that species. But at a higher degree of organization, the distribution and flows of TEs between P. oceanica meadow components, i.e. seagrass shoots, epiphytes, associated algae and animals and detritus, have not been investigated yet. The present study therefore aims to propose a conceptualization model of P. oceanica meadows, regarded as the juxtaposition of the 5 separate components listed above exchanging flows of TEs between themselves and with their environment, i.e. water and sediment. This model can be drawn in energy circuit language. By writing such a model, one in essence is writing equations describing a system. To be relevant, its elaboration requires the compilation of a large amount of quantitative data. This conceptualization can thus be regarded as a collaborative innovation requiring scientists to fill the model through the continuous supplement of new data. In fine, this model will lead to the exact quantification of the role played by P. oceanica meadows in the coastal biogeochemistry of TEsin the Mediterranean. [less ▲]

Detailed reference viewed: 51 (10 ULg)
Full Text
Peer Reviewed
See detailTrace element bioaccumulation and compartmentalization in the invasive algae Caulerpa racemosa var. cylindracea from the Calvi Bay, Corsica
Gobert, Sylvie ULg; Richir, Jonathan ULg

in Langar, H.; Bouafif, C.; Ouerghi, A. (Eds.) Proceedings of the 5th Mediterranean Symposium on Marine Vegetation (2014, October)

The algae Caulerpa racemosa var. cylindracea (Sonder) was first observed along Corsican coasts in 2002 (Ruitton et al., 2005), and more recently in the Calvi Bay (northwestern Corsica) in 2008. Numerous ... [more ▼]

The algae Caulerpa racemosa var. cylindracea (Sonder) was first observed along Corsican coasts in 2002 (Ruitton et al., 2005), and more recently in the Calvi Bay (northwestern Corsica) in 2008. Numerous works have studied the distribution of that invasive species and the factors driving its rapid expansion, as well as the resulting ecological impacts on native coastal communities (Klein and Verlaque, 2008). However, very little is known regarding C. racemosa biochemistry and its natural ability to concentrate trace elements (TEs). In the framework of the STARECAPMED project, this work therefore aimed to study the bioaccumulation and the compartmentalization of 19 TEs in this macroalgae. [less ▲]

Detailed reference viewed: 31 (9 ULg)
See detailVulnerability assessment of ecosystem components to human stressors: the case of a seagrass ecosystem
Giakoumi, S; Possingham, H; Gobert, Sylvie ULg et al

Conference (2014, August 17)

Detailed reference viewed: 27 (4 ULg)
Full Text
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 ▲]

Detailed reference viewed: 44 (6 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 42 (6 ULg)