References of "Gobert, Sylvie"
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See detailEvidence for wastewater influence in a low impacted area throughout stable isotope analyses of the limpet Patella caerulea and epilithic biofilms
Vermeulen, Simon ULg; Lepoint, Gilles ULg; Gobert, Sylvie ULg

Poster (2009, January)

Eutrophication is considered to be one of the main threats to marine environments leading to changes in trophic status of ecosystems and alteration of biological diversity. Carbon and Nitrogen stable ... [more ▼]

Eutrophication is considered to be one of the main threats to marine environments leading to changes in trophic status of ecosystems and alteration of biological diversity. Carbon and Nitrogen stable isotopes analyses were performed on the limpet Patella caerulea and one of its food sources (epilithic biofilms) to assess their potential as early indicators of eutrophication. Samples were seasonally collected in 2005-2006 on five locations gradually exposed to urban sewage in the Calvi Bay and in the Marseilles harbour. Stable isotope signatures of Patella caerulea muscles exhibited steady site - specific values over seasons. In contrast to this time – integrated signal, wide variations in biofilm values show that either composition or isotopic ratios of food sources may vary greatly in time and space. Elevated δ15N values of limpets and biofilms, typical of wastewater influence but unrelated to nitrogen loads, indicate the biological availability of sewage-derived nitrogen in the Calvi Bay and the Marseilles harbour. A reference level of δ15N values is rapidly reached with increasing depth that indicates the limited vertical extent of pollution in the Calvi Bay. [less ▲]

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See detailSeed nutrient content and nutritional status of Posidonia oceanica seedlings in the northwestern Mediterranean Sea
Balestri, Elena; Gobert, Sylvie ULg; Lepoint, Gilles ULg et al

in Marine Ecology. Progress Series (2009), 388

Successful seedling establishment is rare in Posidonia oceanica. The first year after germination is likely to be the most critical phase in the recruitment process, but little is still known on the ... [more ▼]

Successful seedling establishment is rare in Posidonia oceanica. The first year after germination is likely to be the most critical phase in the recruitment process, but little is still known on the factors affecting seedling survival. Mature fruits of P. oceanica released from a meadow of the north-western Mediterranean were deposited by currents on the adjacent beach in May 2004. In May and December 2005, some seedlings established in the previous summer were uprooted by storms and deposited on the beach. This material provided the opportunity to examine seed mass and nutrient content, and the nutritional status of seedlings. Our findings support the hypothesis that growth limitation may be an important cause of mortality for seedlings during the first year of establishment in poor-nutrient sites. [less ▲]

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See detailAssessment of the ecological status of Mediterranean French coastal waters as required by the Water Framework Directive using the Posidonia oceanica Rapid Easy Index: PREI
Gobert, Sylvie ULg; Sartoretto, Stéphane; Rico-Raimondino, Valérie et al

in Marine Pollution Bulletin (2009), 58

This paper describes the PREI (Posidonia oceanica Rapid Easy Index), a method used to assess the ecological status of seawater along Mediterranean French coasts. The PREI was drawn up according to the ... [more ▼]

This paper describes the PREI (Posidonia oceanica Rapid Easy Index), a method used to assess the ecological status of seawater along Mediterranean French coasts. The PREI was drawn up according to the requirements of the Water Framework Directive (WFD 2000/60/EC) and was tested on 24 and 18 stations in PACA (Provence-Alpes-Côtes d’Azur) and Corsica respectively. The PREI is based on five metrics: shoot density, shoot leaf surface area, E/L ratio (Epiphytic biomass/leaf biomass), depth of lower limit, and type of this lower limit. The 42 studied stations were classified in the first four levels of status: high, good, moderate and poor. The PREI values ranged between 0.280 and 0.847; this classification is in accordance with our field knowledge and with our knowledge of the literature. The PREI was validated regarding human pressure levels (r²= 0.74). (http://eurex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2000:327:0001:0072:EN:PDF) [less ▲]

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See detailTrophic diversity among amphipod crustaceans from Posidonia oceanica meadows : A stable isotope assessment
Michel, Loïc ULg; Lepoint, Gilles ULg; Gobert, Sylvie ULg et al

Conference (2008, October 31)

Vagile invertebrates are regarded as key-components of Posidonia oceanica meadow ecosystems, particularly in organic matter transfers from primary producers to higher level consumers. Among these ... [more ▼]

Vagile invertebrates are regarded as key-components of Posidonia oceanica meadow ecosystems, particularly in organic matter transfers from primary producers to higher level consumers. Among these invertebrates, amphipod crustaceans are one of the most abundant and diverse groups, and probably play an important role in meadow ecosystem functioning. However, their trophic ecology is poorly known, and these crustaceans are generally regarded as vegetal epiphytes consumers or generalist detritivores, due to the lack of accurate studies. Here, we focused on the study of the interspecific trophic diversity, and on the importance of other food sources (Posidonia leaves and litter, animal epiphytes, suspended particular organic matter, …) in those amphipods’ diet. To assess these phenomena, we used stable isotopes ratios of carbon and nitrogen as trophic tracers. It appears that, while some species (such as Apherusa chiereghinii and Aora spinicornis) seem to feed mainly on epiphytes, others, like Dexamine spiniventris, exploit different food sources. These results thus tend to show that amphipod trophic diversity could have been underestimated in the past. Moreover, they enhance the comprehension of the feeding ecology of these animals, and therefore of the way they interact with the Posidonia meadow ecosystem. [less ▲]

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See detailMulti-scale spatial variability of amphipod assemblages from the foliar stratum of the Posidonia oceanica (L.) Delile meadow
Sturaro, Nicolas ULg; Lepoint, Gilles ULg; Michel, Loïc ULg et al

Conference (2008, October)

Studying 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 ... [more ▼]

Studying 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. In the Mediterranean coastal zone, the Posidonia oceanica seagrass meadows constitute one of the dominant ecosystems and are an important habitat for vagile invertebrates. Among these, amphipods comprise a large number of species, with considerable abundance and biomass, as well as being an important trophic resource for fish populations. Until now, little attention has been given to the horizontal variability at different spatial scales of amphipod assemblages associated with P. oceanica meadows. A hierarchical sampling design, spanning three orders of magnitude (from 1 to 100s of metres) was elaborated. Sampling was undertaken in March 2007 in the meadows of Calvi Bay (NW Corsica), at depths ranging from 10 to 13 m, using a suction sampler. Our results indicated an important horizontal variability of the studied assemblage, and this at different spatial scales. In addition, these results tend to show that the small scale (~ 1 m and ~ 10 m) influenced abundance, while the medium-scale (~ 100 m) influenced diversity. Some potential causes of the observed patterns are discussed. These results emphasize the importance of considering different spatial scales in the study of the vagile invertebrates associated with P. oceanica meadows. [less ▲]

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See detailPotential use of Paracentrotus lividus as bioindicator for recent trace element pollution monitoring
Richir, Jonathan ULg; Gobert, Sylvie ULg; Bouquegneau, Jean-Marie ULg

Poster (2008, October)

The Mediterranean Sea is an enclosed basin, highly submitted to anthropogenic pressures. Chemical pollution originating from coastal urban centres and industries, or carried by air and rivers, will ... [more ▼]

The Mediterranean Sea is an enclosed basin, highly submitted to anthropogenic pressures. Chemical pollution originating from coastal urban centres and industries, or carried by air and rivers, will primarily affect its coastal ecosystems. The pollution by trace elements into the marine environment is rapidly evolving further to the recent modifications of their production and industrial uses by men. As a result, some trace elements that were previously poorly studied can be considered now as environmental pollutants, whose concentrations can sometimes be way above their natural baseline levels. The purple sea urchin Paracentrotus lividus is a well know bioindicator used for metal pollution monitoring (Fe, Cd, Cr, Pb, Zn and Cu) along the Mediterranean and Atlantic coasts. This sedentary organism successfully concentrates the pollutants diluted in its environment, and the measured concentrations reflect properly the health status of the ecosystem. This study is a first approach on the use of P. lividus as bioindicator for some less investigated trace elements (Al, V, Mn, Co, Ni, Se, Mo and Ag), chosen for their potential toxic effects. We have compared the element concentrations of the digestive tract tissues and gonads of female and male sea urchins. The organisms were frozen prior to dissection, or they were dissected alive, the two experimental procedures being compared afterwards. The existence of an eventual relationship between their gonadic index or their test diameter and the measured pollutant concentrations was also investigated. [less ▲]

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See detailSpatial heterogeneity at small scale in the microbenthic loop of Posidonia oceanica meadows
Pete, Dorothée ULg; Lenartz, Fabian ULg; Velimirov, Branko et al

Conference (2008, October)

In the Mediterranean coastal zone, one the most important ecosystem is the Posidonia oceanica meadow. This seagrass is endemic of the Mediterranean Sea and plays many important ecological roles like ... [more ▼]

In the Mediterranean coastal zone, one the most important ecosystem is the Posidonia oceanica meadow. This seagrass is endemic of the Mediterranean Sea and plays many important ecological roles like oxygen production, nursery for numerous commercial species of fishes and protection of coastal zones by reducing the impact of waves. However, there is a severe lack of informations on small scale variations in its sediment compartment. In an attempt to understand spatial variations in the microbenthic loop (bacteria, organic matter, microphytobenthos and meiofauna) of this ecosystem, an experiment was led in Calvi Bay (Corsica, France), in March 2008, at 10 m depth. Twelve points were sampled randomly in a 125 x 125 cm grid, divided into twenty-five 25 x 25 cm squares, to assess and describe the spatial distribution and variations of different parameters of the sediment. Those parameters are granulometry, density of the P. oceanica meadow, nutrients concentration in pore water, bacteria (biomass, abundance, morphotypes), organic matter (biomass), microphytobenthos (biomass), roots and rhizomes (biomass) and meiofauna (biomass). Distribution maps were produced using the DIVA (Data-Interpolating Variational Analysis) method. Our results prove that the sediment compartment is highly heterogeneous at small scale, especially for bacteria and in the first centimeter of sediment cores. Moreover, a correlation has been established between microphytobenhtos variations and phosphate concentration in pore water. For the first time, such small scale variations are depicted in a P. oceanica meadow, which underlines the importance to take them into account in sampling strategies. [less ▲]

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See detailUnderwater Imagery, a Measuring Tool to Extend the Spatio-Temporal Understanding of Benthic Organisms Dynamics: Case Study of Codium elisabethae in the Azores.
Sirjacobs, Damien ULg; Tempera, Fernando; Cardigos, Frederico et al

Poster (2008, October)

Benthic habitat mapping studies have been increasingly exploiting the use of underwater images to collect information on substrate nature and biological coverage. Concurrently, research has been ongoing ... [more ▼]

Benthic habitat mapping studies have been increasingly exploiting the use of underwater images to collect information on substrate nature and biological coverage. Concurrently, research has been ongoing to develop methods that use the imagery collected to conduct regular quantitative monitoring studies of biological resources distributed over large areas. This study provides the first multi-annual monitoring information on the dynamics of a benthic macroalgae population derived from underwater imagery collected by scuba divers in the Monte da Guia Site of Community Importance /Natura 2000 network (Faial isl. Azores, NE Atlantic). The green alga Codium elisabethae - a long-living green alga that represents a potential good indicator of coastal environmental change - was chosen for the study. The analyses focus on using the underwater imagery to quantify seasonal fluctuations of density, percentage cover, biomass, growth rate and primary production of the species. Two study sites were investigated: one was located in a sheltered no-go reserve exhibiting a dense C. elisabethae population, and the other in a location experiencing more exposed conditions and holding a sparser population. Between August 2003 and November 2005, fifteen (15) photo coverages were collected by scuba-divers. Subsequent processing consisted of producing image mosaics and using automated and interactive change detection methods that recognized, measured and counted individuals present in photos of fixed quadrats and yielded dynamical parameters such as population structures, growth, recruitment, and mortality. Chi-square tests of image-derived estimates and in situ measurements confirmed the validity of a centimeter precision estimation of population structure for individuals above 4 cm diameter. Important variability of population structure and density were observed at small spatial scales. Population density showed a sharp reduction in autumn 2003 and did not show a full recovery in spring and summer 2004. During the following year, population of the protected site maintained density and biomass, while at the exposed site population density dropped. The production of information based on observations of thousands of individuals is mandatory in biological population statistics. The presented imagery approach made it possible, avoiding the need to collect all the measurements and quantitative information during time-constrained SCUBA diving operations. [less ▲]

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See detailImportance of the microbenthic loop of Posidonia oceanica meadows to detect anthropogenic perturbations early: first results
Pete, Dorothée ULg; Velimirov, Branko; Bouquegneau, Jean-Marie ULg et al

Conference (2008, August)

It was demonstrated that Posidonia oceanica, the marine magnoliophyte endemic to the Mediterranean Sea, is a valuable tool to assess environmental qualities of the coastal zones. However, only few studies ... [more ▼]

It was demonstrated that Posidonia oceanica, the marine magnoliophyte endemic to the Mediterranean Sea, is a valuable tool to assess environmental qualities of the coastal zones. However, only few studies have attempted to use characteristics of its sediment compartment as an indicator of the environment state of health. Yet, organisms living in this compartment have a turnover which is faster than for canopy-organisms which makes them useful as valid early descriptors of pollution. The study described here takes place in a project which aims to find an early holistic indicator of anthropogenic perturbations in the Mediterranean coastal zones. The investigation is based on the microbenthic loop (organic matter, bacteria, microphytobenthos and meiofauna) and was led in two different sites of Calvi Bay (Corsica, France), at 10 m depth, in March and June 2007. Only results about bacteria (abundance, biomass, morphotypes), microphytobenthos (biomass) and organic matter (biomass) will be presented. For both seasons, significant differences between sites are found, irrespective on whether variables are treated separately or together, thus indicating that the microbenthic loop has potential to be a good early indicator of pollution. [less ▲]

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See detailSmall scale variations in the microbenthic loop of Posidonia oceanica meadows: an experimental interpolation design.
Pete, Dorothée ULg; Lenartz, Fabian ULg; Velimirov, Branko et al

Poster (2008, August)

In the sediment compartment of Posidonia oceanica meadows, there is a severe lack of information on small scale variations. In an attempt to understand spatial variations of the microbenthic loop ... [more ▼]

In the sediment compartment of Posidonia oceanica meadows, there is a severe lack of information on small scale variations. In an attempt to understand spatial variations of the microbenthic loop (bacteria, organic matter, microphytobenthos and meiofauna), an experiment based on interpolation methods was led in Calvi Bay (Corsica, France), in March 2008, at 10 m depth. Twelve points were sampled randomly in a 125 x 125 cm square, divided into twenty-five 25 x 25 cm squares, to assess and describe the spatial distribution and variations of different parameters of the sediment. Those parameters are granulometry, density of P. oceanica, concentration in nutrients in the pore water, bacteria (biomass, abundance, morphotypes), organic matter (biomass), microphytobenthos (biomass), roots and rhizomes (biomass) and meiofauna (biomass). Results and distribution maps of the respective sediment parameters will be presented for the first time. [less ▲]

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See detailIsotopic ratios and elemental contents as indicators of seagrass C processing and sewage influence in a tropical macrotidal ecosystem (Madagascar, Mozambic channel)
Lepoint, Gilles ULg; Frederich, Bruno ULg; Gobert, Sylvie ULg et al

in Scientia Marina (2008), 72(1), 109-117

Isotopic ratios and elemental concentrations of carbon and nitrogen were measured in seven seagrass species colonising different tidal flats near Toliara (SW Madagascar) in order to determine the ... [more ▼]

Isotopic ratios and elemental concentrations of carbon and nitrogen were measured in seven seagrass species colonising different tidal flats near Toliara (SW Madagascar) in order to determine the potential use of these parameters for assessing C processing and sewage use by tropical seagrasses. Nitrogen concentrations measured in upper intertidal seagrasses near Toliara were almost twice those measured on the tidal flat near a healthy mangrove situated 20 km away from Toliara town. At Toliara Beach, δ15N values were correlated with the N concentrations of Halodule sp., one of the dominant species on the tidal flat. This correlation did not exist for Halophila ovalis, the other dominant species. An increase in N concentrations and δ15N values demonstrates the influence of sewage coming directly onto Toliara Beach on the N cycles of intertidal seagrasses. Nevertheless, this influence seems restricted to the upper littoral zone and was not the main cause of seagrass die-off. On the other hand, at the mangrove site, δ15N values were not correlated with the N concentrations of Halodule sp. or Thalassia hemprichii, showing that natural δ15N variability is driven by other factors than the δ15N of N sources. Moreover, inter-individual variability of δ15N values was greater than inter-specific or inter-site variability, making the δ15N difficult to interpret in the context of human-disturbance influence on the N cycle of tropical seagrasses. δ13C values were close to -9‰, indicating the use of HCO 3– as an inorganic carbon source by the seven investigated species. Contrary to our hypothesis, variation between sites and location on the tidal flat was limited, suggesting limited impact on δ13C values of sewage, emersion duration and mechanisms for HCO 3– incorporation. [less ▲]

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See detailDirective Cadre Eau: Mise en oeuvre du contrôle de surveillance - résultats de la campagne 2006 - district Corse
Boissery, Pierre; Andral, Bruno; Belin, Catherine et al

Report (2007)

Les programmes de surveillance liés à la mise en oeuvre de la DCE sont coordonnés par le Ministère de l’Ecologie et de l’Aménagement durable (MEDAD) et dans chaque bassin hydrographique ce sont les ... [more ▼]

Les programmes de surveillance liés à la mise en oeuvre de la DCE sont coordonnés par le Ministère de l’Ecologie et de l’Aménagement durable (MEDAD) et dans chaque bassin hydrographique ce sont les Agences de l’eau qui, avec l’Etat, prennent en charge l’application, la mise en oeuvre de ces réseaux. Sur la façade méditerranéenne, Ifremer a assuré pour le compte du Schéma Directeur des Données sur l’Eau la maîtrise d’ouvrage de la première campagne du contrôle de surveillance, en coordonnant l’ensemble de l’acquisition des données et de leur synthèse en collaboration avec de nombreux partenaires : Universités, bureaux d’études, structures locales de gestion et services de l’Etat. La mobilisation des différents acteurs autour d’un objectif commun a permis de faire face à la pluridisciplinarité et à la complexité des aspects logistiques de ce programme. Les résultats de cette première campagne du contrôle de surveillance (2006) permettent d’ores et déjà d’avoir une bonne vision d’ensemble de la qualité des eaux littorales à l’échelle du district. Ils confortent les évaluations faites « à dire d’expert » lors de l’état des lieux du district avec des informations nouvelles concernant plus particulièrement la biologie, notamment le benthos de substrat meuble. En eaux côtières, les eaux sont de bonne qualité. En eau de transition, essentiellement lagunaires, il existe une plus grande hétérogénéité des résultats avec des paramètres déclassant relevant plutôt de la biologie, mais sur un nombre important d’indicateurs. [less ▲]

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See detailNocturnal vertical migrations by amphipods of the Posidonia oceanica (L.) Delile foliar stratum : Importance of the litter cover
Michel, Loïc ULg; Sturaro, Nicolas ULg; Lepoint, Gilles ULg et al

Poster (2007, November)

In seagrass meadows, several groups of vagile invertebrates are well known to perform a nocturnal rise from the lower layers of the meadow to the foliar stratum. This vertical migration is generally ... [more ▼]

In seagrass meadows, several groups of vagile invertebrates are well known to perform a nocturnal rise from the lower layers of the meadow to the foliar stratum. This vertical migration is generally regarded as a defense mechanism against predation by diurnal fishes, as well as a mean to maximize the exploitation of trophic resources offered by the meadow. Here, we focused on the amphipods from a Mediterranean Posidonia oceanica meadow. We sampled the community present in the meadows of Calvi Bay (NW Corsica) using two different techniques (hand-towed net and litter collecting). Samples were taken at two seasons, during both night and daytime. Our results confirm the nocturnal rise to the foliar stratum. Combined to an analysis of the recent literature, they also tend to show that amphipods spend the daytime not in the matte itself, as it has been proposed in the past, but in the thin layer of Posidonia litter present at the interface between the foliar stratum and the root/rhizome system. This would emphasize the role of the litter cover in the complexity of the habitat within the meadow, and therefore in the vagile invertebrate community structure and the functioning of the whole meadow as an ecosystem. [less ▲]

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See detailField measurements of inorganic nitrogen uptake by epiflora components of the seagrass Posidonia oceanica (Monocotyledons, Posidoniaceae)
Lepoint, Gilles ULg; Jacquemart, Julien; Bouquegneau, Jean-Marie ULg et al

in Journal of Phycology (2007), 43(2), 208-218

Crustose corallines, crustose and erect brown algae, and sessile animals are major components of the epiphytic community of the Mediterranean seagrass Posidonia oceanica (L.) Delile. Production, biomass ... [more ▼]

Crustose corallines, crustose and erect brown algae, and sessile animals are major components of the epiphytic community of the Mediterranean seagrass Posidonia oceanica (L.) Delile. Production, biomass, and specific composition of this epiphyte-seagrass association are impacted by anthropogenic increase of nutrient load in this oligotrophic area. In this context, nitrogen uptake by P. oceanica and its epiflora was measured using the isotope N-15 at a 10 m depth in the Revellata Bay (Corsica, Mediterranean Sea). Epiflora components showed various seasonal patterns of biomass and abundance. The epiphytic brown algae appeared at the end of spring, later than the crustose corallines, and after the nitrate peak in the bay. Because of their later development in the season, epiphytic brown algae mostly rely on ammonium for their N needs. We hypothesize that the temporal succession of epiphytic organisms plays a crucial role in the N dynamics of this community under natural conditions. The epiphytic brown algae, which have a growth rate one order of magnitude greater than that of crustose corallines, showed lower N-uptake rates. The greater N-uptake rates of crustose corallines probably reflect the greater N requirements (i.e., lower C/N ratios) of red algae. We determined that the epiflora incorporated ammonium and nitrate more rapidly than their host. Nevertheless, when biomass was taken into account, P. oceanica was the most important contributor to N uptake from the water column by benthic macrophytes in this seagrass bed. [less ▲]

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See detailEarly colonization of Posidonia oceanica (L.) Delile by epiphytes: Comparison between natural and artificial seagrass leaves
Pete, Dorothée ULg; Gobert, Sylvie ULg; Lepoint, Gilles ULg et al

in Pergent-Martini, Christine; El Asmi, Souha; Le Ravallec, Célia (Eds.) Proceedings of the third Mediterranean symposium on marine vegetation (2007, March)

Posidonia oceanica is an important marine Magnoliophyta of the Mediterranean coastal zone that can form dense meadows. The leaves of this seagrass are colonized by a lot of organisms, from bacteria to ... [more ▼]

Posidonia oceanica is an important marine Magnoliophyta of the Mediterranean coastal zone that can form dense meadows. The leaves of this seagrass are colonized by a lot of organisms, from bacteria to polychaetes and algae. However, the early stages of colonization are not well known. A preliminary is proposed to examine the nine first days of colonization by epiphytes on natural leaves and on Artificial Seagrass Units (ASUs). Aims of this work were to understand which species are the first to set up, to compare colonization on both leaves and to determine the interest of ASUs in ecological studies. It was shown that the setting up of epiphytes on the bases of both leaves is rapid (first algae on the second day) but the number of organisms increases quicker on ASUs than on natural leaves and on the smooth faces than the rough ones. Shannon-Wiener diversity and evenness were higher for the P. oceanica leaves and the use of Bray-Curtis similarity index showed that colonisation is not similar (between 20 and 30 % similarity) on both leaves for the same day. It can be explained by the lower colonization rate of natural leaves. This lower rate is probably due to a less developed biofilm on natural leaves than on ASUs, to a difficult access to the bases of P. oceanica leaves for epiphytes and microoganisms, and the production of phenol compounds by the plant. Even if ASUs used here do not seem to be similar to natural leaves in early stages of colonization, they could be used in ecological studies thanks to their rapid covering by epiphytes. [less ▲]

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See detailUse of exergy to detect and measure perturbations affecting Posidonia oceanica (L.) Delile meadows: Characterization in the sedimentary compartment
Pete, Dorothée ULg; Bouquegneau, Jean-Marie ULg; Gobert, Sylvie ULg

Poster (2007, March)

Within the scope of the European Water Framework Directive, it seems important to characterize state and evolution of marine ecosystems in a global way. So, it is proposed to use both thermodynamic ... [more ▼]

Within the scope of the European Water Framework Directive, it seems important to characterize state and evolution of marine ecosystems in a global way. So, it is proposed to use both thermodynamic indicators called exergy (Ex) and specific exergy (Exsp) in Posidonia oceanica meadows. Aims of this project are to detect and measure perturbations owed to nutrients loading and mechanical spoiling in the Mediterranean coastal zone. It will be led in the Bay of Calvi, on the microbenthic loop (organic matter, bacteria, microphytobenthos and meiofauna) and will be divided in two parts: sampling in different zone of the meadow and in situ experiments. In the end of this study, it will be possible to give a diagnostic on the health of P. oceanica meadow and to determine how this health will evolve, thanks to the introduction of the exergy in a model. [less ▲]

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See detailLa Posidonie, Cap Sur
Réseau Mer; Gobert, Sylvie ULg

Learning material (2007)

La posidonie sous le regard du scientifique, du gestionnaire, du plongeur, de l'historien, de l'élu du littoral, du plaisancier, du pêcheur, du baigneur et du juriste.

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See detailLong-Term Feeding Ecology and Habitat Use in Harbour Porpoises Phocoena Phocoena from Scandinavian Waters Inferred from Trace Elements and Stable Isotopes
Fontaine, Michael ULg; Tolley, K. A.; Siebert, U. et al

in BMC Ecology (2007), 7

BACKGROUND: We investigated the feeding ecology and habitat use of 32 harbour porpoises by-caught in 4 localities along the Scandinavian coast from the North Sea to the Barents Sea using time-integrative ... [more ▼]

BACKGROUND: We investigated the feeding ecology and habitat use of 32 harbour porpoises by-caught in 4 localities along the Scandinavian coast from the North Sea to the Barents Sea using time-integrative markers: stable isotopes (delta13C, delta15N) and trace elements (Zn, Cu, Fe, Se, total Hg and Cd), in relation to habitat characteristics (bathymetry) and geographic position (latitude). RESULTS: Among the trace elements analysed, only Cd, with an oceanic specific food origin, was found to be useful as an ecological tracer. All other trace elements studied were not useful, most likely because of physiological regulation and/or few specific sources in the food web. The delta13C, delta15N signatures and Cd levels were highly correlated with each other, as well as with local bathymetry and geographic position (latitude). Variation in the isotopic ratios indicated a shift in harbour porpoise's feeding habits from pelagic prey species in deep northern waters to more coastal and/or demersal prey in the relatively shallow North Sea and Skagerrak waters. This result is consistent with stomach content analyses found in the literature. This shift was associated with a northward Cd-enrichment which provides further support to the Cd 'anomaly' previously reported in polar waters and suggests that porpoises in deep northern waters include Cd-contaminated prey in their diet, such as oceanic cephalopods. CONCLUSION: As stable isotopes and Cd provide information in the medium and the long term respectively, the spatial variation found, shows that harbour porpoises experience different ecological regimes during the year along the Scandinavian coasts, adapting their feeding habits to local oceanographic conditions, without performing extensive migration. [less ▲]

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