References of "Bouquegneau, Jean-Marie"
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See detailHeavy Metals Contamination and Body Condition of Wintering Guillemots (Uria Aalge) at the Belgian Coast from 1993 to 1998
Debacker, Virginie ULg; Jauniaux, Thierry ULg; Coignoul, Freddy ULg et al

in Environmental Research (2000), A84(3), 310-317

A sample of 166 common guillemots (Uria aalge) recovered from Belgian beaches during five wintering seasons, from 1993-1994 to 1997-1998, were examined. At necropsy, postmortem examination including body ... [more ▼]

A sample of 166 common guillemots (Uria aalge) recovered from Belgian beaches during five wintering seasons, from 1993-1994 to 1997-1998, were examined. At necropsy, postmortem examination including body mass, fat reserves, presence or not of intestinal contents, eventual status of oiling, and pathological changes (cachexia, acute hemorrhagic gastroenteropathy (GEAH)) was attributed to each individual. Mild to severe cachexia, a pathology characterized by moderate to severe atrophy of the pectoral muscle as well as reduced amounts or absence of subcutaneous and/or abdominal fat, was observed for most specimens (85.8%). Heavy metal analyses (Cu, Zn, Fe, Cd, Ni, Cr, and Pb) of the tissues (typically liver, kidney, and pectoral muscle) were performed, and total lipids were determined (liver and pectoral muscle). The guillemots collected at the Belgian coast exhibited higher Cu and Zn concentrations compared to individuals collected in more preserved areas of the North Sea such as the northern colonies. A general decrease of their total body mass as well as liver, kidney, and pectoral muscle mass was associated to increasing cachexia severity. Moreover, significantly increasing heavy metal levels (Cu and Zn) in the tissues as well as depleted muscle lipid contents were observed parallel to increasing cachexia severity. On the contrary the organs' total metal burden barely correlates to this status. These observations tend to indicate a general redistribution of heavy metals within the organs as a result of prolonged starvation and protein catabolism (cachectic status). Such a redistribution could well be an additional stress to birds already experiencing stressfull conditions (starvation, oiling). [less ▲]

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See detailCharacterisation and potential role of metallothioneins in marine mammals
Das, Krishna ULg; Jacob, Valérie; Debacker, Virginie ULg et al

in Comparative Biochemistry and Physiology (2000, July), 126A(Supp. 1), 37

In the framework of a North Sea and adjacent areas monitoring, metallothioneins (MTs) have been studied in livers and kidneys of 8 marine mammals species collected on the Belgian coast and in the ... [more ▼]

In the framework of a North Sea and adjacent areas monitoring, metallothioneins (MTs) have been studied in livers and kidneys of 8 marine mammals species collected on the Belgian coast and in the Northeast Atlantic between 1993 and 2000: the harbour porpoise Phocoena phocoena , the harbour seal Phoca vitulina, the white beaked dolphin Lagenorhynchus albirostris, the white sided dolphin Lagenorhynchus acutus, the sperm whale Physeter macrocephalus, the fin whale Balaenoptera physalus, the common dolphin Delphinus delphis and the striped dolphin Stenella coeruleoalba. The participation of this protein in metal detoxification has been investigated since high levels of cadmium (Cd) and mercury (Hg) have been measured in livers and kidneys of those marine mammals. It appears that MT concentrations vary widely in marine mammals tissues (from 50 to more than 2000 µg.g–1 dw) underlying the numerous parameters involved: species, tissue, physiological status, pregnancy, age, diet and metal level. The percentage of the cytosolic Cd bound to MTs can reach almost 100%. On the contrary, the percentage of hepatic and renal Hg bound to MT is very low (generally less than 10 %) and this metal is mainly associated with selenium (HgSe) under a detoxified form in the insoluble fraction of the tissues. Characterisation of renal MTs of white-sided dolphin has been performed: the protein has two isoforms (MT-1 and MT-2) with a molecular weight estimated around 6800. MT-1 can bind Cu, Zn, Hg and Cd while MT-2 only binds Zn, Hg and Cd suggesting different metabolic functions for the two isoforms. MT-2 was also more abundant than MT-1. To conclude, MTs appear to play a minor role in the binding and detoxification of Hg by marine mammals. On the contrary, close and dynamic interactions occur between Cd and MTs. White-sided dolphin metallothioneins has two isoforms likely characterised by different metabolic functions in relation with cellular homeostasis and cadmium detoxification. [less ▲]

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See detailApport des isotopes stables du carbone et de l’azote dans l’étude des réseaux trophiques
Bouquegneau, Jean-Marie ULg; Das, Krishna ULg; Gobert, Sylvie ULg et al

Conference (2000, June 13)

Trois types de producteur primaire prolifèrent dans la zone photique côtière méditerranéenne. En dehors des zones d’upwelling et des apports côtiers naturels ou d’origine anthropique, le bloom ... [more ▼]

Trois types de producteur primaire prolifèrent dans la zone photique côtière méditerranéenne. En dehors des zones d’upwelling et des apports côtiers naturels ou d’origine anthropique, le bloom phytoplantonique est de courte durée et les eaux méditerranéennes sont très claires. Les algues benthiques ont une biomasse relativement faible et le principal producteur primaire est l’herbier à Posidonia oceanica (L.) Delile. Cet herbier constitue un écosystème complexe, d’une importance cruciale pour l’équilibre côtier (maintien des côtes, production d’oxygène, plusieurs milliers d’espèces y sont inféodées…). Son influence se fait également ressentir bien au-delà de sa limite de distribution (exportation vers les zones profondes). Les feuilles et les épiphytes de l’herbier sont à la base de nombreuses chaînes trophiques. Les rapports isotopiques (13C/12C et 15N/14N) mesurés dans les tissus d’un animal reflètent ceux de son alimentation avec un léger enrichissement d’un niveau trophique à un autre. Cet discrimination en faveur des isotopes lourds est de l’ordre 30/00 pour le 15N et de 10/00 pour le 13C. Les rapports 15N/14N permettent donc la détermination de la position trophique d’un organisme. Les rapports 13C/12C sont plutôt de bons indicateurs des sources de production primaire. L’application de cette technique au cas d’un herbier à P. oceanica, a permis sur base des rapports 13C/12C de distinguer trois sources primaires de nourriture: la matière particulaire en suspension, les algues (épiflore de P. oceanica et macroalgues) et P. oceanica. Les rapports isotopiques 13C/12C et 15N/14N de différentes catégories trophiques d’organismes capturés dans l’herbier et dans une communauté épilithe adjacente suggèrent que les sources de nourriture sont semblables dans les deux communautés: la matière particulaire en suspension et les algues. La communauté épiphyte des feuilles de posidonie est une source de nourriture très importante pour les organismes de la canopée de l’herbier. Les posidonies ne représentent qu’une partie mineure du régime alimentaire des organismes étudiés à l’exception des holothuries et du téléostéen herbivore Sarpa salpa. Ce poisson est l’un des consommateurs principaux de posidonie vivantes mais la majorité de sa nourriture provient de matériel algal. Les holothuries psamivores assimilent massivement des détritus issus de P. oceanica et jouent ainsi un rôle clé dans le recyclage in situ de ce matériel. La disponibilité en nutriments, en particulier de l'azote inorganique, est un des facteurs majeurs déterminant la dynamique des écosystèmes à phanérogames marines. Le budget en azote de ces plantes est très complexe car elles ont la capacité d'incorporer les nutriments dissous dans la colonne d'eau et dans l'eau interstitielle du sédiment. De plus, le recyclage interne de l'azote est souvent considéré comme un processus clé pour assurer les besoins de la plante. Des expériences utilisant l'isotope 15 de l'azote comme traceur nous ont permis de mesurer in situ l'incorporation de nitrate et d'ammonium ainsi que le recyclage interne de l'azote par P. oceanica. L'incorporation d'azote exogène par les feuilles ne représenterait que 25% des besoins annuels en azote de la plante et le recyclage 40%. Par différence, nous pouvons estimer que l'incorporation d'azote par les racines représenterait environ 35% des besoins annuels en azote de la plante. Nos études isotopiques se sont également avérées particulièrement intéressantes dans la compréhension des processus de transfert de matières organiques ou de polluants au niveau des échelons trophiques supérieurs (thons et dauphins de l’Atlantique nord et mammifères marins de la Mer du Nord). En effet, au sein d’un même écosystème peuvent coexister différentes espèces de prédateurs nécessitant des ressources similaires. L’analyse simultanée des isotopes stables du carbone et de l’azote a permis une définition plus fine de l’écologie alimentaire de ces espèces. [less ▲]

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See detailDetermination of trophic status of seabirds using carbon and nitrogen isotopes.
Nyssen, Fabienne; Lepoint, Gilles ULg; Dauby, Patrick ULg et al

Poster (2000, May)

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See detailUse of stable isotopes to delineate amphipod trophic status in Antarctic food webs
Nyssen, Fabienne ULg; Brey, Thomas; Lepoint, Gilles ULg et al

Poster (2000, May)

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See detailMarine mammals stranded on the Belgian and Dutch coasts: Approach of their feeding ecology by stable isotope and heavy metal measurements
Das, Krishna ULg; Debacker, Virginie ULg; Lepoint, Gilles ULg et al

Poster (2000, April)

The harbour porpoise Phocoena phocoena, the harbour seal Phoca vitulina and the white-beaked dolphin Lagenorhynchus albirostris are commonly found stranded on the Belgian and Dutch coasts. More ... [more ▼]

The harbour porpoise Phocoena phocoena, the harbour seal Phoca vitulina and the white-beaked dolphin Lagenorhynchus albirostris are commonly found stranded on the Belgian and Dutch coasts. More occasionally, oceanic species such as the white-sided dolphin Lagenorhynchus acutus, the sperm whale Physeter macrocephalus or the fin whale Balaenoptera physalus are also found stranded. For the last 10 years, trace analyses (Cd, Pb, Cu, Zn, Se, Hg) have been performed in their organs as well as complementary stable isotope ratio determinations (d15N and d13C) in order to trace their respective metal level and trophic position. Sperm whales, fin whales and white-sided dolphins display strong differences in their d13C and d15N values compared to harbour porpoises, harbour seals or white-beaked dolphins. The isotopic data from white-sided dolphins, sperm whales and fin whales suggest that they do not feed mainly within this area. On the contrary, porpoises, seals and white-beaked dolphins display close isotopic data reflecting a similar nutrition within the North Sea. However significant differences appear between these species: harbour porpoises display a significantly lower d15N (mean: 16.4 0/00 against 18.70/00 and 18.8 0/00 respectively) and d3C (mean-17 0/00 against –16 0/00 and –15.70/00 respectively) than harbour seals and white-beaked dolphins reflecting a lower trophic position of the porpoises.Moreover, Harbour porpoise isotopic compositions seem to have changed over the last five years, which could reflect a switch in their diet. In marine mammals, heavy metals are mainly absorbed through the diet and so potential relations between stable isotopes and heavy metals have been investigated. For example, it is suggested that harbour porpoises occasionally feed on cadmium contaminated preys as squids and that harbour seals and white-beaked dolphins are more restrictive on fish. [less ▲]

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See detailSpatial and interspecies variability of mercury accumulation in small cetaceans
Holsbeek, Ludo; Das, Krishna ULg; Joiris, C. R. et al

Poster (2000, April)

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See detailMetallothioneins in Marine Mammals
Das, Krishna ULg; Debacker, Virginie ULg; Bouquegneau, Jean-Marie ULg

in Cellular and Molecular Biology (2000), 46(2),

Metallothioneins (MTs) have been detected in livers and kidneys of 10 marine mammals species (Pinnipeds and Odontocetes). Characterization of renal MTs of striped dolphin has shown that the protein has ... [more ▼]

Metallothioneins (MTs) have been detected in livers and kidneys of 10 marine mammals species (Pinnipeds and Odontocetes). Characterization of renal MTs of striped dolphin has shown that the protein has two isoforms (MT-1 and MT-2) with a molecular weight estimated around 6,800. MT concentrations also vary widely in marine mammals tissues (from 58 to 1,200 microg x g(-1) ww) underlying the numerous parameters involved: physiological status, pregnancy, age, diet. The participation of this protein in metal detoxification has been investigated since high levels of cadmium (Cd) and mercury (Hg) have been measured in livers and kidneys of marine mammals. It has been suggested that those animals can mitigate at least in part, the toxic effects of Cd and Hg through binding to MTs. The percentage of the cytosolic Cd bound to MTs can reach almost 100%. On the contrary, the percentage of hepatic and renal Hg bound to MT is very low (generally less than 10%) and this metal is mainly associated with selenium (HgSe) under a detoxified form in the insoluble fraction of the tissues. MTs appear to play a minor role in the binding and detoxification of Hg by marine mammals. On the contrary, close and dynamic interactions occur between Cd and MTs. Cytosolic MTs appear as a potential short term way of detoxification of Cd accumulated from diet. Long-term detoxification would imply a sequestration of the metal under a precipitated form (e.g. in lysosomes). [less ▲]

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See detailTuna and dolphin associations in the Northeast Atlantic: Evidence of different ecological niches from stable isotope and heavy metal measurements
Das, Krishna ULg; Lepoint, Gilles ULg; Loizeau, Véronique et al

in Marine Pollution Bulletin (2000), 40

Associations of tunas and dolphins in the wild are quite frequent events and the question arises how predators requiring similar diet in the same habitat share their environmental resources. As isotopic ... [more ▼]

Associations of tunas and dolphins in the wild are quite frequent events and the question arises how predators requiring similar diet in the same habitat share their environmental resources. As isotopic composition of an animal is related to that of its preys, stable isotopes (13C/12C and 15N/14N) analyses were performed in three predator species from the Northeast Atlantic: the striped dolphin, Stenella coeruleoalba, the common dolphin Delphinus delphis, and the albacore tuna, Thunnus alalunga, and compared to their previously described stomach content. Heavy metals (Cd, Zn, Cu and Fe) are mainly transferred through the diet and so, have been determined in the tissues of the animals. Tunas muscles display higher delta15N than in common and striped dolphins (mean: 11.4 0/00 vs. 10.3 0/00 and 10.4 0/00, respectively) which reflects its higher trophic level nutrition. Higher delta13C are found in common (-18.4 0/00) and striped dolphin (-18.10/00) muscles than in albacore tuna (-19.3 0/00) likely in relation with its migratory pattern. The most striking feature is the presence of two levels of cadmium concentrations in the livers of the tunas (32 mg kg-1 dry weight vs. 5 mg kg-1 dry weight). These two groups also differ by their iron concentrations and their delta15N and delta 13C liver values. These results suggest that in the Biscay Bay, tunas occupy two different ecological niches likely based on different squid input in their diet. [less ▲]

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See detailMarine mammals from the North Sea: Approach of their feeding ecology through stable isotope and cadmium measurements
Das, Krishna ULg; Lepoint, Gilles ULg; Debacker, Virginie ULg et al

Poster (2000)

The fertile waters of the North Sea represent one major life site for at least three different marine mammal species: the harbour porpoise, Phocoena phocoena , the harbour seal, Phoca vitulina, and the ... [more ▼]

The fertile waters of the North Sea represent one major life site for at least three different marine mammal species: the harbour porpoise, Phocoena phocoena , the harbour seal, Phoca vitulina, and the white-beaked dolphin, Lagenorhynchus albirostris. More occasionally, oceanic species such as the white-sided dolphin Lagenorhynchus acutus, the sperm whale Physeter macrocephalus or the fin whale Balaenoptera physalus can be sighted or found stranded. Very few data dealing with marine mammal diet in the North Sea are available. In order to contribute to the feeding ecology of these North Sea marine mammals, Cd as well as 15N and 13C measurements have been performed in their tissues. Sperm whales and white-sided dolphins display high renal Cd levels (258 µg.g-1 and 88 µg.g-1 dry weight respectively). Mean Cd concentrations measured in harbour porpoise, harbour seal, white beaked dolphin and fin whale kidneys remain low (mean: 5, 0.9, 0.5 and 4 µg.g-1 respectively). However, some adult porpoises display renal Cd concentrations higher than 10 µg.g-1. Mean 13C measured in the muscles of sperm whales, fin whales and white-sided dolphins are more negative compared to harbour porpoise, harbour seal or white-beaked dolphin mean value. Cd contaminated porpoises display significant lower muscle 13C than other porpoises. Both low d13C and high Cd levels suggest a greater reliance of white-sided dolphins, sperm whales on oceanic cephalopods. It appears that some harbour porpoises can also feed on oceanic squids suggesting dynamic interactions between the North Sea and the North Atlantic porpoise populations. [less ▲]

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See detailUse of stable isotope to delineate amphipod trophic status in Antarctic food webs
Nyssen, Fabienne ULg; Brey, Tom; Lepoint, Gilles ULg et al

in Polish Archives for Hydrobiology (2000), 47

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See detailRelative impact of a seagrass bed and its adjacent epilithic algal community in consumer diets
Lepoint, Gilles ULg; Nyssen, Fabienne ULg; Gobert, Sylvie ULg et al

in Marine Biology (2000), 136

The aim of this work was to identify and compare, using nitrogen and carbon stable isotope data, the food sources supporting consumer communities in a Mediterranean seagrass bed (Gulf of Calvi, Corsica ... [more ▼]

The aim of this work was to identify and compare, using nitrogen and carbon stable isotope data, the food sources supporting consumer communities in a Mediterranean seagrass bed (Gulf of Calvi, Corsica) with those in an adjacent epilithic algal dominated community. Isotopic data for consumers are not significantly different in the two communities. Particulate matter and algal material (seagrass epiflora and dominant epilithic macroalgae) appear to be the main food sources in both communities. Generally, the 13C of animals suggests that the seagrass Posidonia oceanica (L.) Delile represents only a minor component of their diet or of the diet of their prey, but the occurrence of a mixed diet is not excluded. P.oceanica dominates the diet of only of few species, among which holothurians appear as key components in the cycling of seagrass material. [less ▲]

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See detailFauna vs flora contribution to the leaf epiphytes biomass in a Posidonia oceanica seagrass bed (Revellata Bay, Corsica).
Lepoint, Gilles ULg; Havelange, Stéphane; Gobert, Sylvie ULg et al

in Hydrobiologia (1999), 394

The epiphyte biomass of Posidonia oceanica (L.) Delile leaves is mainly related to the substrate leaf availability. It decreases with increasing depth and increases from winter to summer, following the ... [more ▼]

The epiphyte biomass of Posidonia oceanica (L.) Delile leaves is mainly related to the substrate leaf availability. It decreases with increasing depth and increases from winter to summer, following the leaf biomass changes. In Revellata Bay (Gulf of Calvi, Corsica), at shallow depth (10m in this study) where photophilous algae grow, the fixed epifauna biomass accounts for about one third of leaf epiphytes biomass. At deeper depths in the Revellata Bay (20 and 30m), where shade-tolerant algae are dominant among epiflora, epifauna may account for more than half the leaf epiphytes biomass. [less ▲]

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