References of "Das, Krishna"
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See detailTrophic relationships and mercury biomagnification in Brazilian tropical coastal food webs
Bisi, Tatiana; Lepoint, Gilles ULg; de Freitas Azevedo et al

in Ecological Indicators (2012), 18(0), 291-302

The present study investigated trophic relationships and mercury flow through food webs of three tropical coastal ecosystems: Guanabara, Sepetiba and Ilha Grande bays. The investigation was carried out ... [more ▼]

The present study investigated trophic relationships and mercury flow through food webs of three tropical coastal ecosystems: Guanabara, Sepetiba and Ilha Grande bays. The investigation was carried out through carbon and nitrogen stable isotopes (δ13C, δ15N) and total mercury (THg) determination in muscle from 35 species, including crustacean, cephalopod, fish and dolphin species. Detritivorous species showed the lowest average δ15N values in all bays. These species were 13C enriched in Sepetiba and Ilha Grande bays, suggesting the presence of 13C enriched macroalgae in their diet. The highest mean δ15N values were found in fish and benthic invertebrate feeders, as well as in species presenting demerso-pelagic feeding habit. The carbon and nitrogen isotopic findings showed different trophic relationship in food webs from Sepetiba, Guanabara and Ilha Grande bays. Guanabara Bay showed to be depleted in δ15N compared to both Sepetiba and Ilha Grande bays. The latter finding suggests substantial contribution of atmospheric nitrogen fixation by cyanobacteria. A positive linear relationship was found between log THg concentrations and δ15N values for Guanabara and Ilha Grande bays, but not for Sepetiba Bay. Our findings showed trophic magnification factors (TMF) above 1, demonstrating that THg is being biomagnified up the food chains in Rio de Janeiro bays. Highlights ► The δ13C and δ15N findings showed different trophic relationship in food webs from Rio de Janeiro bays. ► Guanabara Bay showed depleted δ15N values compared to Sepetiba and Ilha Grande bays. ► Ilha Grande Bay showed significant depleted δ13C values. ► Our findings indicate THg biomagnifications up food webs in Rio de Janeiro bays. ► Ilha Grande Bay food web showed the highest trophic magnification factor. [less ▲]

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See detailComputational toxicology: Physiologically based pharmacokinetic models (PBPK) for lifetime exposure and bioaccumulation of polybrominated dephenyl ethers (PBDEs) in marine mammals
Weijs, Liesbeth; Covaci, Adrian; Yang, Raymond S H et al

in Environmental Pollution (2012)

Due to migration of harbour porpoises towards more polluted areas like the North Sea and their sensitivity towards pollution, there is a need for proper conservation measures for this species. As a ... [more ▼]

Due to migration of harbour porpoises towards more polluted areas like the North Sea and their sensitivity towards pollution, there is a need for proper conservation measures for this species. As a consequence, knowledge about the pollutant’s kinetics is required. The present study is the first to investigate the kinetics of PBDEs in marine mammals using PBPK modeling as a non-destructive tool for describing the chemical’s kinetics in a protected animal species. The models were developed and parameterized using data from the literature and Black Sea harbour porpoises through computer opti- mization. The predictability of these models in time was assessed by reverse dosimetry modeling using data from North Sea porpoises (1990e2008). From these predictions, PBDE 99 levels were found to decrease the fastest, followed by PBDE 153, 47 and 100. Results show that the PBPK models can be applied for harbour porpoises from different regions and also simulate time trends. [less ▲]

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See detailToxicokinetics of selenium in Chelonians: trophic exposure in Trachemys scripta scripta
Dyc, Christelle ULg; Greco, Anaïs; Das, Krishna ULg

(2011, December)

Background. Se is primordial for all development stages in oviparous species but can induce cellular damages (e.g. oxidative stress, histopathotoxicity) , embryo- and immunotoxicity (Usdi 1998; Hoffman ... [more ▼]

Background. Se is primordial for all development stages in oviparous species but can induce cellular damages (e.g. oxidative stress, histopathotoxicity) , embryo- and immunotoxicity (Usdi 1998; Hoffman 2002) , even at low concentration. Unlike birds and fishes, little is currently known on Se toxicology in reptiles, such as turtles. Most studies reported tissue burdens from field-captured or death animals but rarely provided an understanding of the dose, duration or pathway of exposure. Our present study aims to investigate toxicokinetic of Se through an in vivo and per os exposure of the yellow-bellied slider turtle Trachemys scripta scripta. Furthermore relationship between Se concentration in internal tissues (liver, kidney, muscle ) and external tissues (carapace, skin, blood) will evaluate usefulness of these last in the framework of non-invasive sampling in protected turtle species. Methodology. 160 yellow-bellied slider turtles, around four weeks old, were acquired in September 2010 and placed by pair in individual tank for a six-month acclimatization period. Lengths, as straight carapace length SCL, ranged from 1.7 to 6.4 cm. Three groups of 42 individuals each were designed. The feeding trial consisted in an eight-week supplementation period followed by a four-week depuration period. At some intervals during that time scale, six individuals per group were sacrificed and tissues were collected (carapace, scutes, skin, blood, liver, kidney, muscle) for selenium analysis. During the supplementation period, turtles were fed with diet containing 0 (control) , 23 or 47 µg.g-1 of selenium as seleno-L-methionine. During the depuration period, the remaining individuals were fed with non-supplemented control diet. Total selenium was investigated by ICPMS. Results and discussion. The Se-concentration in all collected tissues increased in a dose-dependent way over the course of the supplementation period. Se accumulation had no effect on survival, diet behavior or growth. Higher Se levels were observed in kidney, followed by muscle and blood. During the recovery period, Se levels decreased in tissues in a significantway except in blood, muscle and carapace. Blood, skin and carapace Se levels were positively correlated to those in kidney and muscle. Such relationships were also observed between liver and carapace, and blood. Results suggested a Se transfer through the food intake and the potential use of carapace and skin as relevant tools in non-invasive biomonitoring studies. [less ▲]

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See detailMarine predators as sentinels for our oceans and human health
Das, Krishna ULg; Bouquegneau, Jean-Marie ULg

Conference (2011, November 08)

“During the course of the 20th century, the planet became and is now chemically different from any previous time”. (1) Organic and inorganic chemicals occur in greater abundance because of human activity ... [more ▼]

“During the course of the 20th century, the planet became and is now chemically different from any previous time”. (1) Organic and inorganic chemicals occur in greater abundance because of human activity and end up in the ocean. As more humans inhabit coastal regions, question arises about the health of our oceans. Marine vertebrates such as marine fish, turtles, birds and mammals are used to get early warning about negative trends and impact linked to anthropogenic activities. Such organisms are qualified as sentinel species (2). In turn, sentinels will permit us to better characterize and potentially manage negative impacts on human and animal health associated with our oceans. Marine predators including marine mammals and birds can present elevated concentrations of these organic and inorganic chemicals in their tissues, due to their high position in the trophic chain, their life span, and their fat store in which lipophilic chemicals accumulate. Humans and marine predators share common routes of exposures such as (1) the maternal transfer through placenta and milk and (2) trophic transfer through ingestion of marine fish and shellfish. Furthermore, some human population rely on marine mammal consumption for subsistence. Marine predators offer a snapshot of ocean health that could potentially impact human health. In the hope that this paper will stimulate the research much needed for assessing ocean health in the context of a rapidly changing environment, we provide here a review of (i) levels and trends of contaminants and relationships with biotic and abiotic factors, (ii) toxicological effects and (iii) spatial and geographical trends in tissues of marine predators. We conclude this communication by presenting several necessary perspectives such a more thorough follow of organic and inorganic pollutants in the marine environment including the use of isotopic tracers to assess the local versus global aspects of marine pollution. (1) Reddy, C. M., Stegeman, J. J. & Hahn, M. E. in Oceans and human Health (eds P.J. Walsh et al.) 121-144 (Academic Press, 2008). (2) Bossart G.D. (2011). Vet. Path. 48:676-690. [less ▲]

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See detailEcotoxicology of marine predators: Strategy and perspectives
Das, Krishna ULg

Scientific conference (2011, October 25)

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See detailBlood dynamics of mercury and selenium in northern elephant seals during the lactation period
Habran, Sarah ULg; Debier, Cathy; Crocker, Dan et al

in Environmental Pollution (2011), 159(10), 2523-2529

The effects of reproduction and maternal investment (i.e., milk transfer) on trace element levels remain poorly understood in marine mammals. We examined the blood dynamics of mercury (Hg) and selenium ... [more ▼]

The effects of reproduction and maternal investment (i.e., milk transfer) on trace element levels remain poorly understood in marine mammals. We examined the blood dynamics of mercury (Hg) and selenium (Se) during lactation in the northern elephant seal (Mirounga angustirostris), a top predator from the North Pacific Ocean. Total Hg and Se levels were measured in whole blood and milk of 10 mother-pup pairs on days 5 and 22 of lactation. Both Hg and Se were transferred to offspring through the milk. Results suggested that the maternal transfer of Se was prominent during lactation, whereas the Hg transfer was larger during gestation. The lactation period affected Hg and Se levels in the blood of elephant seal mothers and pups. Physiological processes and their relationship to body condition should be considered carefully when interpreting trace element levels in the framework of biomonitoring. [less ▲]

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See detailPotential effects of blood contaminants on immune responses in harbour seals (Phoca vitulina)
Dupont, Aurélie ULg; Weijs, Liesbeth; Siebert, Ursula et al

Poster (2011, August 23)

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See detailDynamics of trace elements in grey seals throughout the lactation period
Habran, Sarah ULg; Pomeroy, P. P.; Debier, Cathy et al

Conference (2011, May 17)

The effects of reproduction and maternal investment (i.e. milk transfer) on trace element levels remain poorly understood in marine mammals. We examined the blood dynamics of Cd, Pb, Hg, Cr, Ni, V, Zn, Cu ... [more ▼]

The effects of reproduction and maternal investment (i.e. milk transfer) on trace element levels remain poorly understood in marine mammals. We examined the blood dynamics of Cd, Pb, Hg, Cr, Ni, V, Zn, Cu, Fe, Ca and Se throughout lactation in a top predator from the North Sea, the grey seal (Halichoerus grypus). Trace element levels were measured in blood and milk of 21 mother-pup pairs in early and late lactation. Maternal hair and natal fur (lanugo) were also collected and analyzed. Trace element levels in blood decreased according to the following pattern: Fe > Ca > Zn > Se > Cu > Hg > Pb > Cr > V in mothers and pups. Cd and Ni were not detected in blood. The substantial levels measured in lanugo indicate nevertheless that all trace elements (including Cd and Ni) were transferred to offspring through the placenta. In maternal hair, Pb levels (~ 2.2 mg/kg dw) were relatively high in comparison with other phocid species. All trace elements, except Cd, were detected in the milk showing a transmammary transfer to offspring, especially for elements such as Ca, Se, V, Ni and Pb. Hg showed the highest levels in blood (up to 0.25 mg/kg ww) and hair (up to 21 mg/kg dw) from the non-essential and toxic metals measured. Levels of Hg and essential elements (Ca, Fe, Zn, Cu and Se) in blood and milk showed significant variations throughout the lactation period. Therefore, physiological processes such as lactation affect trace element levels in tissues of mother and pup elephant seals. Such processes and its relationship to body condition should be considered carefully when interpreting trace element levels in the framework of biomonitoring. [less ▲]

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See detailSTUDY OF SELENITE AND SELENOMETHIONINE EFFECT ON METHYLMERCURY IN VITRO TOXICITY
Dupont, Aurélie ULg; Siebert, Ursula; Rosenberger, Tanja et al

Conference (2011, May 16)

Methylmercury (MeHg) and selenium (Se) can be found at elevated concentrations in blood of marine mammals and both display modulatory effects on the immune system. Whereas mercury (Hg)-Se antagonism in ... [more ▼]

Methylmercury (MeHg) and selenium (Se) can be found at elevated concentrations in blood of marine mammals and both display modulatory effects on the immune system. Whereas mercury (Hg)-Se antagonism in liver of marine mammals is well known, the protective role of Se against Hg immunotoxicity in marine mammals has been poorly described. We propose here an in vitro approach using combined Hg and Se in vitro exposure of peripheral blood mononuclear cells (PBMCs) of the harbor seal (Phoca vitulina). PBMCs were isolated from the blood of 10 harbor seals and exposed to environmental concentrations of MeHg (1µM) and selenite or selenomethionine (5µM), respectively inorganic and organic forms of Se. MeHg leaded to a decrease of lymphocyte proliferation, to an increase of cells with compromised mitochondrial membrane potentials and cell death. Preliminary results evidenced that none of the two Se forms had a protective effect against MeHg toxicity, although cells were slightly stimulated by Se alone. Therefore MeHg expresses its toxicity among blood circulating lymphocytes in presence or absence of selenite or selenomethionine. [less ▲]

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See detailThe harbor seal and the harbor porpoise from the North Sea: review of their ecotoxicological status based on stranded and free-ranging individuals and potential threaths to the population
Das, Krishna ULg; Weijs, Liesbeth; Habran, Sarah ULg et al

Conference (2011, May)

The harbor seal (Phoca vitulina) and the harbor porpoise (Phocoena phocoena) from the North Sea have experienced major fluctuations these last decades due to habitat loss, prey fluctuation and pollution ... [more ▼]

The harbor seal (Phoca vitulina) and the harbor porpoise (Phocoena phocoena) from the North Sea have experienced major fluctuations these last decades due to habitat loss, prey fluctuation and pollution of the marine environment. Recently, development of monitoring programs and non-invasive sampling techniques, including seal catches in Germany allowed blood sampling together with measurements of blubber thickness, body mass, sex and body length. This approach is complementary to the study of stranded and by-caught individuals sampled during necropsies. Essential (Se, Zn, Cu, Fe) and non-essential elements (T-Hg, MeHg, Cd, Pb), perfluorinated organochemicals (PFCs) polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) were measured in blubber and in blood (for selected compounds) of stranded, by-caught and free-ranging individuals from Belgian and German coasts. In contrast to Cd and Pb, hepatic T-Hg can reach concentrations as high as 2.1 μg.g-1 dry weight but depended on several factors including position in the trophic chain (inferred from δ13C and δ15N values), age group and the body mass. This level has been shown to generate in vitro toxicity on harbor seal lymphocytes. Organic compound analysis (PFCs, PCBs, PBDEs) revealed widespread dispersion of contaminants in the marine environment with higher concentrations in seals compared to porpoises in agreement with the higher trophic position of the harbor seal. However, metabolization of these compounds differed between the two species, as revealed by the higher contribution of the persistent BDE-47 and lower chlorinated and non-persistent congeners (e.g. CB 52, CB95) in tissues of harbor porpoises. T-Hg, PFCs, PCBs and PBDEs were detected in calves confirming maternal transfer to offspring. These pollutants are strongly suspected to affect the immune and endocrine systems as well as vitamin A metabolism and this raises concern about exposure-related health effects, especially in younger individuals. [less ▲]

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See detailThyroid endocrine disruption in situ and in vivo experiments reveals compensatory mechanisms
Schnitzler, Joseph ULg; Celis, Niko; Klaren, Peter et al

Conference (2011, May)

We compared effects of in situ and in vivo exposure of EDC on teleost thyroid system in order to get a complete picture of the putative interactions. A 120-day experimental exposure was designed in ... [more ▼]

We compared effects of in situ and in vivo exposure of EDC on teleost thyroid system in order to get a complete picture of the putative interactions. A 120-day experimental exposure was designed in combination to in situ measurements of persistent organic pollutants in 87 wild sea bass (Dicentrarchus labrax) form European estuaries. Seventy-five individuals were exposed to doses of PCB (0.3 to 1.0 µg Σ7PCBs per g food pellets) that reflects the persistent organic pollution to which the European sea bass population could conceivably be exposed. We applied a series of recommended measurement endpoints in these studies. The centrally controlled thyroidal secretion of T4 was monitored adequately from the muscular T4 levels and from thyroid histological appearance. Muscular T3 levels and enzymatic deiodinase and sulfatase activities in liver were measured. Observations made in experimental exposure to environmental relevant doses of PCB were consistent with those made in our field study. In both studies the muscular T4 levels were unaffected and no multivariate relationship with contaminant exposure could be revealed. Measurements of follicular diameter and epithelial cell heights showed no significant differences. Our findings revealed an increase of the hepatic T4ORD activity by higher chlorinated PCB congeners and DDTs. In both studies, we observed a general decrease the thyroid hormone conjugation by sulfatases that increases their solubility and facilitates their excretion. The muscular T3 levels were well preserved. These changes likely represent compensatory responses to disrupting effects that might otherwise have depressed T3 levels. This approach permitted us to interpret the causes and implications of alterations of the teleost thyroid system. [less ▲]

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See detailYou are what you eat, plus a few per mill: apport des isotopes stables en écologie marine. PARTIM 2- Traçage des polluants chez les mammifères et autres vertébrés marins
Das, Krishna ULg; Lepoint, Gilles ULg

Scientific conference (2011, April 27)

L’utilisation en écologie des isotopes stables d’éléments chimiques légers (H, C, N, O, S) est relativement récente et montre un développement exponentiel ces dernières années. L’évolution rapide des ... [more ▼]

L’utilisation en écologie des isotopes stables d’éléments chimiques légers (H, C, N, O, S) est relativement récente et montre un développement exponentiel ces dernières années. L’évolution rapide des techniques permettant les mesures des abondances relatives naturelles de ces isotopes et leur automatisation est à l’origine de ce développement. D’autre part, la production de molécules marquées (i.e. présentant un rapport isotopique stable non naturel) ouvre de nombreuses perspectives expérimentales. Le premier objectif de ce cours-conférence est de fournir les notions de bases nécessaires à la compréhension des applications des isotopes stables en écologie, et en particulier, en écologie marine. Le second objectif est de donner un large aperçu des utilisations potentielles des abondances isotopiques (naturelles ou expérimentalement modifiées) et de les illustrer par des exemples concrets, tirés de la littérature scientifique récente. La seconde leçon sera focalisée sur des exemples combinant approche isotopique et écotoxicologie appliquée aux vertébrés marins. En effet, l’utilisation combinée du profil en polluants des vertébrés marins et de leur composition isotopique permet d’une part d’appréhender les sources de ces contaminations (i.e. océanique vs terrestre, benthique vs pélagique) et d’autre part d’éclairer la structure de leurs populations et d’éventuelles variations de leurs niches écologiques. [less ▲]

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See detailYou are what you eat, plus a few per mille": apport des isotopes stables en écologie marine PARTIM 1: Introduction et Application générale
Lepoint, Gilles ULg; Das, Krishna ULg

Scientific conference (2011, April 26)

Dans les années 50, les premiers isotopistes découvrirent que les rapports d’abondance des isotopes stables d’éléments légers variaient dans les compartiments de la lithosphère et de l’hydrosphère. Cette ... [more ▼]

Dans les années 50, les premiers isotopistes découvrirent que les rapports d’abondance des isotopes stables d’éléments légers variaient dans les compartiments de la lithosphère et de l’hydrosphère. Cette découverte fut rapidement exploitée dans le domaine des géosciences et de la géophysique. Plus récemment, dans les années 70- 80, il fut démontré que les compositions isotopiques variaient également entre compartiments de la biosphère et que ces variations étaient informatives dans divers champs d’application des sciences biologiques et humaines (y compris archéologie par exemple). Pour cette raison, l’audience pouvant assister à cette leçon est extrêmement large, même si nous proposons de centrer notre propos sur l’application des mesures de rapports isotopiques dans le domaine des sciences de l’environnement. D’autre part, les évolutions technologiques récentes (i.e. automatisation des analyses, mesures en routine des rapports isotopiques du carbone, azote, oxygène et souffre; mesure des rapports isotopiques de composés spécifiques) conduisent à une diversification exponentielle des domaines d’aplication des mesures isotopiques en écologie (par exemple études des réseaux trophiques, flux d’énergie dans les écosystèmes, problème de diversifications trophiques, anthropisation des écosystèmes, biogéographie et phénomène migratoire, etc.). Cette diversification se traduit dans l’élaboration d’outils mathématiques (modèle de mélange, niches isotopiques par exemple) et expérimentaux et par des synergies de plus en plus étroites entre les diverses approches. Pour ces raisons, les techniques isotopiques sont tout-à-fait pertinentes en terme de développement technologique et scientifique actuel, mais également en terme de transdisciplinarité. La leçon-conférence proposée se divise en deux cours de 2 heures chacun : le premier cours introductif permettra d’établir le cadre général de l’utilisation des isotopes stables en écologie (en particulier écologie des réseaux trophiques) , et présentera sommairement quelques cas concrets d’utilisation (et des limites d’utilisation) en écologie terrestre et marine. Le second cours développera les synergies possibles entre études écotoxicologiques et études isotopiques, appliquées à l’études des vertébrés marins. En effet, les concentrations en polluants chez ces espèces dépendent non seulement de la contamination de leur environnement mais également de plusieurs facteurs biotiques, parmi lesquels le régime alimentaire. Des molécules telles que les polychlorobiphényles, les diphényléthers polybromés, les pesticides organochlorés, les composés perfluorinés et les métaux toxiques sont détectés à plus ou moins haute concentration dans les tissus des vertébrés marins. Certains de ces composés sont sujets au phénomène de biomagnification : l’étude des valeurs en δ15N des organismes permet ainsi de situer leur position trophique et d’estimer le potentiel d’accumulation d’une substance dans la chaîne trophique. D’autres types de contaminations, comme certains composés perfluorinés sont liés à la proximité du milieu terrestre et sont associés aux valeurs en δ13C. Les concentrations en polluants combinées aux rapports isotopiques peuvent également fournir des indications tout à fait originales sur la structure des populations des mammifères marins. Partim 1:Le premier cours (Dr. Gilles Lepoint) se divisera comme suit : Qu’est-ce qu’un isotope stable ? Quels sont les isotopes d’intérêt biologique ? Variabilité isotopique dans la biosphère et problématique du fractionnement isotopique. Quelques exemples généraux d’applications (recherche de fraude, migrations animales, …) Intérêt et limites des isotopes stables en tant que traceurs trophiques. Modèles de mélange. Quelques exemples d’application écologiques (réseau trophique associé aux posidonies, diversité et variabilité ontogénique des niches trophiques des poissons coralliens, Complémentarité avec d’autres traceurs trophiques et Rapports isotopiques de composés spécifiques. [less ▲]

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See detailNew insights in the toxicology and health status of marine marine mammals: Use of free-ranging harbour seals from the Wadden Sea
Das, Krishna ULg; Seibel, Henrike; Hasseilmeier, Ilka et al

Conference (2011, March 20)

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See detailThyroid hormone disrupting chemicals in sea bass (Dicentrarchus labrax) from European coasts
Schnitzler, Joseph ULg; Michel, Loïc ULg; Klaren, Peter et al

Conference (2011, February 25)

Polychlorinated biphenyls (PCBs) and organochlorine pesticides like Dichloro-Diphenyl-Trichloroethane (DDTs), Hexachlorocyclohexanes (HCHs), aldrin, dieldrin and trace elements (Cd, Cu, Se, Pb, Zn and Hg ... [more ▼]

Polychlorinated biphenyls (PCBs) and organochlorine pesticides like Dichloro-Diphenyl-Trichloroethane (DDTs), Hexachlorocyclohexanes (HCHs), aldrin, dieldrin and trace elements (Cd, Cu, Se, Pb, Zn and Hg) were analysed in the muscle of sea bass (Dicentrarchus labrax) sampled in coastal regions near several important European river mouths (Gironde, Charente, Loire, Seine and Scheldt). These potential endocrine disrupting chemicals were present in European coastal waters. Even if their concentrations were well below the Maximum Residue Limits set by the governments, they induced alterations of the endocrine system. We established correlations between contaminant concentrations and effects on the thyroid system in sea bass. The contaminants induced modifications of the metabolic pathways of thyroid hormones and enhanced thyroid hormone synthesis. The activity of T4 Outer Ring Deiodinase was increased, that leads to an intensified conversion of thyroxine (T4) to its more biologically active form triiodothyronine (T3). Meanwhile, the activity of T4 sulfatation was reduced, that leads to a lowered biliary excretion of thyroid hormones. The modified metabolic pathways of the thyroid hormones can be interpreted as a tool to homeostatically maintain the thyroid hormone status. Of all tested compounds, the higher chlorinated PCBs seemed to be the most implicated in this perturbation. The nature of thyroid hormone synthesis, signalling and regulation is highly conserved among vertebrates. Although we cannot extrapolate thyroid toxicity data directly from one species to another, these environmental factors may well affect thyroid function in other species, including humans. [less ▲]

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See detailEvaluation of the ecotoxicological effects of POPs and heavy metals, reflecting pathological, microbiological and genetic analyses, on the Mekong River population of Irrawaddy dolphins (Orcaella brevirostris)
Siebert, Ursula; Das, Krishna ULg

Report (2011)

For this report, samples of Irrawaddy River dolphins found dead along the Mekong River between 2006 and 2010 were analysed in different laboratories in Europe, Canada and Cambodia. The aim of the ... [more ▼]

For this report, samples of Irrawaddy River dolphins found dead along the Mekong River between 2006 and 2010 were analysed in different laboratories in Europe, Canada and Cambodia. The aim of the investigation was to gain additional knowledge on histological and toxicological findings as well as on the genetic variation of the Mekong population. The report summarizes those results in relation to previous investigations conducted in Cambodia and the United States of America. [less ▲]

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See detailToothed whales in the northwestern Mediterranean: Insight into their feeding ecology using chemical tracers
Praca, Emilie; Laran, Sophie; Lepoint, Gilles ULg et al

in Marine Pollution Bulletin (2011), 62(5), 1058-1065

Risso’s dolphins, pilot whales and sperm whales rarely strand in the northwestern Mediterranean. Thus, their feeding ecology, through the analysis of stomach contents, is poorly known. The aim of this ... [more ▼]

Risso’s dolphins, pilot whales and sperm whales rarely strand in the northwestern Mediterranean. Thus, their feeding ecology, through the analysis of stomach contents, is poorly known. The aim of this study was to gain further insight into the segregation/superposition of the diet and habitat of Risso’s dolphins, pilot whales and sperm whales using chemical tracers, namely, stable isotopes (d13C, d15N) and orga- nochlorines. Significantly different d15N values were obtained in Risso’s dolphins (11.7 ± 0.7‰), sperm whales (10.8 ± 0.3‰) and pilot whales (9.8 ± 0.3‰), revealing different trophic levels. These differences are presumably due to various proportions of Histioteuthidae cephalopods in each toothed whale’s diet. Similar d13C contents between species indicated long-term habitat superposition or corroborated impor- tant seasonal migrations. Lower congener 180 concentrations (8.20 vs. 21.73 lg.g􏰀1 lw) and higher tDDT/ tPCB ratios (0.93 vs. 0.42) were observed in sperm whales compared with Risso’s dolphins and may indi- cate wider migrations for the former. Therefore, competition between these species seems to depend on different trophic levels and migration patterns. [less ▲]

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See detailA non-invasive approach to study lifetime exposure and bioaccumulation of PCBs in protected marine mammals: PBPK modeling in harbor porpoises
Weijs, Liesbeth; Covaci, Adrian; Yang, Raymond S. H. et al

in Toxicology and Applied Pharmacology (2011), 256

In the last decade, physiologically based pharmacokinetic (PBPK) models have increasingly been developed to explain the kinetics of environmental pollutants in wildlife. For marine mammals specifically ... [more ▼]

In the last decade, physiologically based pharmacokinetic (PBPK) models have increasingly been developed to explain the kinetics of environmental pollutants in wildlife. For marine mammals specifically, these models provide a new, non-destructive tool that enables the integration of biomonitoring activities and in vitro studies. The goals of the present study were firstly to develop PBPK models for several environmental relevant PCB congeners in harbor porpoises (Phocoena phocoena), a species that is sensitive to pollution because of its limited metabolic capacity for pollutant transformation. These models were tested using tissue data of porpoises from the Black Sea. Secondly, the predictive power of the models was investigated for time trends in the PCB concentrations in North Sea harbor porpoises between 1990 and 2008. Thirdly, attempts were made to assess metabolic capacities of harbor porpoises for the investigated PCBs. In general, results show that parameter values from other species (rodents, humans) are not always suitable in marine mammal models, most probably due to differences in physiology and exposure. The PCB 149 levels decrease the fastest in male harbor porpoises from the North Sea in a time period of 18†years, whereas the PCB 101 levels decrease the slowest. According to the models, metabolic breakdown of PCB 118 is probably of lesser importance compared to other elimination pathways. For PCB 101 and 149 however, the presence of their metabolites can be attributed to bioaccumulation of metabolites from the prey and to metabolic breakdown of the parent compounds in the harbor porpoises. [less ▲]

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