References of "Lepoint, Gilles"
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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 diet of the Harlequin crab Lissocarcinus orbicularis, an obligate symbiont of sea cucumbers (holothuroids) belonging to the genera Thelenota, Bohadschia and Holothuria
Caulier, Guillaume; Lepoint, Gilles ULg; Van Nedervelde, Fleur et al

in Symbiosis (2014)

The present paper characterizes, for the first time, the diet of the Harlequin crab, Lissocarcinus orbicularis an obligate symbiotic crab that associates with sea cucumbers (holothuroids) belonging to the ... [more ▼]

The present paper characterizes, for the first time, the diet of the Harlequin crab, Lissocarcinus orbicularis an obligate symbiotic crab that associates with sea cucumbers (holothuroids) belonging to the genera Thelenota, Bohadschia and Holothuria. These tropical holothuroids host a rich symbiotic community in the Indo-West Pacific Ocean of which the Harlequin crab is the best known. The diet of L. orbicularis was characterized by analyzing the microscopic, molecular and isotopic signatures obtained from its gastric content. The presence of sea cucumber ossicles in the gastric mills of the crabs suggests that symbionts eat the superficial integument of their host and this was suppoarted by the fact that Holothuroid DNA was detected in the stomach of L.orbicularis after DGGE and sequencing of the 18S rDNA gene. The stable isotopic δ13C and δ15N values of crab tissues were compared with diverse potential food sources including the three holothuroids, three algae, one sea grass as well as the organic matter contained in the water column, in the sediment, and the second most abundant symbiont, the polychaete Gastrolepidia clavigera. The low δ15N values of crabs suggest that the crabs do not exclusively feed on sea cucumber tissue but assimilate diverse food sources such as sea grasses and organic matter contained in sediment that have similar δ13C values. There were no difference between the feeding of males and females but there was a positive correlation between the carapace length and the stable isotopic values indicating a shift of the food source as crabs grow larger. [less ▲]

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See detailBrominated and phosphorus flame retardants in White-tailed Eagle Haliaeetus albicilla nestlings: Bioaccumulation and associations with dietary proxies (δ13C, δ15N and δ34S)
Eulaers, Igor; Jaspers, Veerle; Halley, Duncan et al

in Science of the Total Environment (2014), 478

Very little is known on the exposure of high trophic level species to current-use brominated (BFRs) and phosphorus flame retardants (PFRs), although observations on their persistence, bioaccumulation ... [more ▼]

Very little is known on the exposure of high trophic level species to current-use brominated (BFRs) and phosphorus flame retardants (PFRs), although observations on their persistence, bioaccumulation potential, and toxicity have been made. We investigated the accumulation of BFRs and PFRs, and their associations with dietary proxies (δ13C, δ15N and δ34S), in plasma and feathers of White-tailed Eagle Haliaeetus albicilla nestlings from Trøndelag, Norway. In addition to accumulation of a wide range of polybrominated diphenyl ether (PBDE) congeners in both plasma and feathers, all non-PBDE BFRs and PFRs could be measured in feathers, while in plasma only two of six PFRs, i.e. tris-(2-chloroisopropyl) phosphate (TCIPP) and tris-(2,3-dichloropropyl) phosphate (TDCPP) were detected. PFR concentrations in feathers (0.95-3,000 ng g-1) were much higher than selected organochlorines (OCs), such as polychlorinated biphenyl 153 (CB 153; 2.3-15 ng g-1) and dichlorodiphenyldichloroethylene (p,p’-DDE; 2.3-21 ng g-1), PBDEs (0.03-2.3 ng g-1) and non-PBDE BFRs (0.03-1.5 ng g-1). Non-significant associations of PFR concentrations in feathers with those in plasma (P≥0.74), and their similarity to reported atmospheric PFR concentrations, may suggest atmospheric PFR deposition on feathers. Most OCs and PBDEs, as well as tris(chloroethyl) phosphate (TCEP), tris(phenyl) phosphate (TPHP) and tri-(2-butoxyethyl) phosphate (TBOEP) were associated to δ15N and/or δ13C (all P≤0.02). Besides δ15N enrichment, δ34S was depleted in nestlings from fjords, inherently close to an urbanised centre. As such, both may have been a spatial proxy for anthropogenic disturbance, possible confounding their use as dietary proxy. [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 detailTrophic Relationships and Habitat Preferences of Delphinids from the Southeastern Brazilian Coast Determined by Carbon and Nitrogen Stable Isotope Composition
Bisi, Tatiana; Dorneles, Paulo; Lailson-Brito, José et al

in PLoS ONE (2013), 8(12),

To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ13C) and nitrogen (δ15N) isotopes in muscle samples of the following 10 delphinid species: Sotalia ... [more ▼]

To investigate the foraging habitats of delphinids in southeastern Brazil, we analyzed stable carbon (δ13C) and nitrogen (δ15N) isotopes in muscle samples of the following 10 delphinid species: Sotalia guianensis, Stenella frontalis, Tursiops truncatus, Steno bredanensis, Pseudorca crassidens, Delphinus sp., Lagenodelphis hosei, Stenella attenuata, Stenella longirostris and Grampus griseus. We also compared the δ13C and δ15N values among four populations of S. guianensis. Variation in carbon isotope results from coast to ocean indicated that there was a significant decrease in δ13C values from estuarine dolphins to oceanic species. S. guianensis from Guanabara Bay had the highest mean δ13C value, while oceanic species showed significantly lower δ13C values. The highest δ15N values were observed for P. crassidens and T. truncatus, suggesting that these species occupy the highest trophic position among the delphinids studied here. The oceanic species S. attenuata, G. griseus and L. hosei had the lowest δ15N values. Stable isotope analysis showed that the three populations of S. guianensis in coastal bays had different δ13C values, but similar δ15N results. Guiana dolphins from Sepetiba and Ilha Grande bays had different foraging habitat, with specimens from Ilha Grande showing more negative δ13C values. This study provides further information on the feeding ecology of delphinids occurring in southeastern Brazil, with evidence of distinctive foraging habitats and the occupation of different ecological niches by these species in the study area. [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 detailMeiofauna and harpacticoid copepods in different habitats of a Mediterranean seagrass meadow
Mascart, Thibaud ULg; Lepoint, Gilles ULg; De Troch, Marleen

in Journal of the Marine Biological Association of the United Kingdom (2013), 93(06), 1557-1566

This study investigated whether associated meiobenthic communities, especially harpacticoid copepods differed, amongst habitats. Five pre-defined habitats within and next to the Posidonia oceanica ... [more ▼]

This study investigated whether associated meiobenthic communities, especially harpacticoid copepods differed, amongst habitats. Five pre-defined habitats within and next to the Posidonia oceanica seagrass meadow were sampled: living seagrass canopy leaves (LL), small (SMF) and large (LMF) macrophytodetritus fragments accumulations and sand, bare (BS) and covered (CS). The highest meiofauna abundances were recorded in the BS for the core sampled habitats (BS, CS, SMF and LMF) and in the LMF for seagrass material habitats (SMF, LMF and LL). Harpacticoid copepods were the most abundant taxon in all habitats. The assemblage composition at copepod family level showed two distinct habitats clusters: a leaf (LMF and LL) and a sediment cluster (BS, CS and SMF). Subsequently, stable isotope analyses were conducted to analyse the relationship between copepods and their potential food sources in seagrass material habitats. Based on δ13C isotopic analyses and SIAR mixing model, harpacticoid copepods relied for 70% on epiphytes and for 30% on P. oceanica leaf material in the LMF and LL habitats. [less ▲]

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See detailStables isotopes in the fin whale Balaenoptera physalus from the Mediterranean Sea: implications for management and conservation
Das, Krishna ULg; Lepoint, Gilles ULg; Michel, Loïc ULg et al

Poster (2013, April)

The fin whale (Balaenoptera physalus) is the commonest large whale species in the Mediterranean Sea, found mostly over deep, offshore waters of the western and central portion of the region. This whale is ... [more ▼]

The fin whale (Balaenoptera physalus) is the commonest large whale species in the Mediterranean Sea, found mostly over deep, offshore waters of the western and central portion of the region. This whale is known to feed mainly on krill in contrast to its Atlantic counterpart, displaying a more diversified diet. δ13C and δ15N values were analysed by IR-MS (Isoprime 100) coupled to an N-C-S elemental analyser (Vario MICRO Cube, Elementar) in 113 skin biopsies from Mediterranean fin whales sampled in 2010 and 2011 during WWF campaign at sea. A lipid normalization equation was applied (adapted from Post al. 2007) because the measured C:N ratio was > 3.5. Normalized δ13C and δ15N values ranged from -20.3 to -17.3 ‰ and from 5.9 to 8.9 ‰, respectively. These values are in good agreement with those collected previously on baleen plates from Mediterranean fin whales (Bentaleb et al., 2011). A mean enrichment of 3.4 ‰ was observed between δ15N values measured in fin whale skin biopsies and Mediterranean krill (Meganyctiphanes norvegica) confirming the importance of the krill as a major food source. The narrow width of the isotopic niche of the Mediterranean fin whale (evaluated by SIBER Stable Isotope Bayesian Ellipses) compared to the Atlantic fin whale (Ryan et al. 2012) raises many concerns in the context of global changes and long-term consequences. One could expect that species displaying narrow niches would be more susceptible to ecosystem fragmentation and other anthropogenic impacts. [less ▲]

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

in Aquatic Toxicology (2013), 140-141

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

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

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See detailDiet- and tissue-specific incorporation of isotopes in the shark Scyliorhinus stellaris, a North Sea mesopredator
Caut, Stephane; Jowers, Michael J.; Michel, Loïc ULg et al

in Marine Ecology. Progress Series (2013), 492

Elucidating predator–prey relationships is an important part of understanding and assessing the structure and function of ecosystems. Sharks are believed to play a significant role in marine ecosystems ... [more ▼]

Elucidating predator–prey relationships is an important part of understanding and assessing the structure and function of ecosystems. Sharks are believed to play a significant role in marine ecosystems, although their specific trophic ecology is largely unexplored. Stable isotopes of nitrogen ( 15N) and carbon ( 1318 C) are a widely applied tool in food web studies but there is a need to quantify stable isotope dynamics in animals, particularly sharks. In this study, diet-tissue discrimination factors (DTDF = stable isotope in consumer tissue – stable isotope in diet) and turnover rates (time for the isotope to be assimilated into the consumer’s tissue) of stable isotopes were estimated in blood, fin, and muscle tissue for the shark species Scyliorhinus stellaris fed two diets with different isotope values. Subsequently, these diet- and tissue-specific DTDFs were used in isotopic mixing models to quantify the diet of Scyliorhinus canicula caught in the North Sea and compared with stomach content data. DTDFs for 15N ( 15N) and 13C ( 13C) ranged from –1.95‰ to 3.49‰ and from 0.52‰ to 5.14‰, respectively, and varied with tissue and diet type. Isotope turnover rates in plasma and red blood cells, expressed as half-lives, range from 39 to 135 days. A majority of the variability of DTDFs reported in this and other studies with sharks can be explained by linear relationships between DTDF and dietary isotopic values. From these relationships, we propose a method for isotope mixing models that uses diet specific DTDFs, which improves diet reconstruction estimates of animals, particularly mesopredator sharks that consume a large range of prey types. [less ▲]

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See detailDiet of harbor porpoises along the Dutch coast: a combined stable isotope and stomach contents approach
Jansen, Okka; Michel, Loïc ULg; Lepoint, Gilles ULg et al

in Marine Mammal Science (2013), 29(3), 295-311

High stranding frequency of porpoises, Phocoena phocoena, along the Dutch coast since 2006 has led to increased interest in the ecology of porpoises in the North Sea. Stranded porpoises were collected ... [more ▼]

High stranding frequency of porpoises, Phocoena phocoena, along the Dutch coast since 2006 has led to increased interest in the ecology of porpoises in the North Sea. Stranded porpoises were collected along the Dutch coast (2006–2008) and their diet was assessed through stomach content and stable isotope analysis (d13C and d15N) of porpoise muscle and prey. Stable isotope analysis (SIAR) was used to estimate the con- tribution of prey species to the porpoises’ diet. This was compared to prey composi- tion from stomach contents, to analyze differences between long- and short-term diet. According to stomach contents, 90.5% of the diet consisted of gobies, whiting, lesser sandeel, herring, cod, and sprat. Stable isotope analysis revealed that 70-83% of the diet consisted of poor cod, mackerel, greater sandeel, lesser sandeel, sprat, and gobies, highlighting a higher importance of pelagic, schooling species in the porpoises’ diet compared to stomach contents. This could be due to prey distribution as well as differ- ences in behavior of porpoises and prey between the coastal zone and offshore waters. This study supports the need for multi-method approaches. Future ecological and fishery impact assessment studies and management decisions for porpoise conservation should acknowledge this difference between the long- and short-term diet. [less ▲]

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See detailFactors influencing the bioaccumulation of persistent organic pollutants in food webs of the Scheldt estuary
Van Ael, Evy; Covaci, Adrian; Das, Krishna ULg et al

in Environmental Science & Technology (2013)

Concentrations of several persistent organic pollutants (POPs: PCBs, PBDEs, OCPs) in aquatic species from the Scheldt estuary were related with factors (body size, lipids, trophic position), possibly ... [more ▼]

Concentrations of several persistent organic pollutants (POPs: PCBs, PBDEs, OCPs) in aquatic species from the Scheldt estuary were related with factors (body size, lipids, trophic position), possibly influencing their bioaccumulation. Stable nitrogen isotope ratios (δ15N) were used as a measure for trophic position. A decreasing trend in POP levels towards the sea was observed. For POP concentrations in sediments, this trend could be attributed to a dilution effect from mixing with seawater. However, concentrations in biota more downstream were higher than expected after taking into account the dilution effect, possibly due to differences in bioavailability. Tissue concentrations were correlated with the lipid content in biota, but not with body size. Biomagnification was only significant for some PCB congeners and p,p'-DDE at the most marine sampling location (Terneuzen, L1) and for p,p'-DDD and BDE 100 at the second sampling location (Bath, L2). A significant decreasing relationship was found for ɣ-HCH concentrations with increasing δ15N at Terneuzen. For Antwerpen (L3), no significant relationships were detected. TMFs ranged from 0.64 for ɣ-HCH up to 1.60 for PCB 194. These results suggest that biomagnification was more important in the marine part of the estuary, although the presence of multiple carbon sources at the freshwater side might have led to an underestimation of the influence of trophic position. [less ▲]

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

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

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

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

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See detailInorganic carbon fixation by chemosynthetic ectosymbionts and nutritional transfers to the hydrothermal vent host-shrimp Rimicaris exoculata
Ponsard, Julie ULg; Cambon-Bonavita, Marie-Anne; Zbinden, Magali et al

in ISME Journal (The) (2013), 7

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

Poster (2012, November 26)

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

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

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

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

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

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

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