Krishna Das

Publications

• 3.43

  Impact points

  Computational toxicology: Physiologically based pharmacokinetic models (PBPK) for lifetime exposure and bioaccumulation of polybrominated diphenyl ethers (PBDEs) in marine mammals.

  Liesbeth Weijs, Adrian Covaci, Raymond S H Yang, Krishna Das, Ronny Blust

  Environmental pollution (Barking, Essex : 1987). 04/2012; 163:134-41.

  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 ... [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 optimization. The predictability of these models in time was assessed by reverse dosimetry modeling using data from North Sea porpoises (1990-2008). 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.
• 3.25

  Impact points

  Environmental factors affecting thyroid function of wild sea bass (Dicentrarchuslabrax) from European coasts.

  Joseph G Schnitzler, Peter H M Klaren, Jean-Marie Bouquegneau, Krishna Das

  Chemosphere. 12/2011;

  Thyroid functional status of wild fish in relation with the contamination of their environment deserves further investigation. We here applied a multi-level approach of thyroid function assessment in 87 wild sea bass collected near several estuaries: namely the Scheldt, the Seine, the Loire, the Cha... [more] Thyroid functional status of wild fish in relation with the contamination of their environment deserves further investigation. We here applied a multi-level approach of thyroid function assessment in 87 wild sea bass collected near several estuaries: namely the Scheldt, the Seine, the Loire, the Charente and the Gironde. Thyroxine (T(4)) and triiodothyronine (T(3)) concentrations in muscle were analyzed by radioimmunoassay. The activity of hepatic enzymes involved in extrathyroidal pathways of thyroid hormone metabolism, viz. deiodination, glucuronidation and sulfatation were analyzed. Last, follicle diameter and epithelial cell heights were measured. We observed changes that are predicted to lead to an increased conversion of T(4)-T(3) and lowered thyroid hormone excretion. The changes in the metabolic pathways of thyroid hormones can be interpreted as a pathway to maintain thyroid hormone homeostasis. From all compounds tested, the higher chlorinated PCBs seemed to be the most implicated in this perturbation.
• 3.36

  Impact points

  A non-invasive approach to study lifetime exposure and bioaccumulation of PCBs in protected marine mammals: PBPK modeling in harbor porpoises.

  Liesbeth Weijs, Adrian Covaci, Raymond S H Yang, Krishna Das, Ronny Blust

  Toxicology and applied pharmacology. 08/2011; 256(2):136-45.

  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 ac... [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 18years, 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.
• 3.12

  Impact points

  Thyroid dysfunction in sea bass (Dicentrarchus labrax): underlying mechanisms and effects of polychlorinated biphenyls on thyroid hormone physiology and metabolism.

  Joseph G Schnitzler, Niko Celis, Peter H M Klaren, Ronny Blust, Alin C Dirtu, Adrian Covaci, Krishna Das

  Aquatic toxicology (Amsterdam, Netherlands). 08/2011; 105(3-4):438-47.

  The current study examines the effect of subchronic exposure to a mixture of Aroclor standards on thyroid hormone physiology and metabolism in juvenile sea bass. The contaminant mixture was formulated to reflect the persistent organic pollution to which the European sea bass population could conceiv... [more] The current study examines the effect of subchronic exposure to a mixture of Aroclor standards on thyroid hormone physiology and metabolism in juvenile sea bass. The contaminant mixture was formulated to reflect the persistent organic pollution to which the European sea bass population could conceivably be exposed (0.3, 0.6 and 1.0 μg Σ7PCBs per g food pellets) and higher (10 μg Σ7PCBs per g food pellets). After 120 days of exposure, histomorphometry of thyroid tissue, muscular thyroid hormone concentration and activity of enzymes involved in metabolism of thyroid hormones were assessed. Mean concentrations of 8, 86, 142, 214 and 2279 ng g(-1)ww (Σ7 ICES PCB congeners) were determined after 120 days exposure. The results show that the effects of PCB exposures on the thyroid system are dose-dependent. Exposure to environmentally relevant doses of PCB (0.3-1.0 μg Σ7PCBs per g food pellets) induced a larger variability of the follicle diameter and stimulated hepatic T(4) outer ring deiodinase. Muscular thyroid hormone levels were preserved thanks to the PCB induced changes in T(4) dynamics. At 10 times higher concentrations (10 μg Σ7PCBs per g food pellets) an important depression of T(3) and T(4) levels could be observed which are apparently caused by degenerative histological changes in the thyroid tissue.
• 3.51

  Impact points

  Cadmium toxicokinetics and bioaccumulation in turtles: trophic exposure of Trachemys scripta elegans.

  Elodie Guirlet, Krishna Das

  Ecotoxicology (London, England). 08/2011; 21(1):18-26.

  Ecotoxicological data in reptiles are mainly represented by field studies reporting the tissue burden of wild-captured individuals but much less is known regarding the processes of uptake, depuration, accumulation and the effects of inorganic contaminants in these species. In the present study, the ... [more] Ecotoxicological data in reptiles are mainly represented by field studies reporting the tissue burden of wild-captured individuals but much less is known regarding the processes of uptake, depuration, accumulation and the effects of inorganic contaminants in these species. In the present study, the accumulation, the path and the effects of exposure to cadmium (Cd) through diet intake were investigated in female red eared slider turtles, Trachemys scripta elegans. In the first phase of the experiment, turtles underwent an acclimatization period during which they were fed a control diet. In the second phase, the turtles were exposed to cadmium through a CdCl(2) supplemented-diet with increased environmentally relevant concentrations for a period of 13 weeks. Following this, the turtles went through a third phase, a recovery phase of 3 weeks, during which they were fed uncontaminated food. Blood and feces were collected during the three phases of the experiment. The turtles were euthanized at the end of the experiment and organ samples collected. The Cd-concentrations in blood remained stable over the course of the experiment while Cd-concentrations in feces increased with time and with the amount of Cd ingested. The proportional accumulation in liver and kidney together was comprised between 0.7 and 6.1% and they represented the main organs of accumulation. Cd accumulated in the organs in the following order of concentration: kidney > liver > pancreas > muscle. In terms of burden in organs, the Cd-burden was the highest in liver followed by kidney and pancreas. The proportional accumulation decreased as Cd ingestion increased, suggesting that at a higher dose of Cd, assimilation decreased. Mineral content of the liver and pancreas became modified according to Cd level; increasing dietary Cd exposure increased concentrations of zinc and iron in liver and copper in pancreas in a dose-dependent manner. Accumulation of Cd had no effect on survival, food consumption, growth, weight or length suggesting no effect of the treatment on female turtle body condition.
• 3.43

  Impact points

  Blood dynamics of mercury and selenium in northern elephant seals during the lactation period.

  Sarah Habran, Cathy Debier, Daniel E Crocker, Dorian S Houser, Krishna Das

  Environmental pollution (Barking, Essex : 1987). 07/2011; 159(10):2523-9.

  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... [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.
• 2.91

  Impact points

  Organochlorine pesticides, polychlorinated biphenyls and trace elements in wild European sea bass (Dicentrarchus labrax) off European estuaries.

  Joseph G Schnitzler, Jean Pierre Thomé, Mario Lepage, Krishna Das

  The Science of the total environment. 06/2011; 409(19):3680-6.

  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 European sea bass (Dicentrarchus labrax) sampled in Atlantic coa... [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 European sea bass (Dicentrarchus labrax) sampled in Atlantic coastal regions near several important European river mouths (Gironde, Charente, Loire, Seine and Scheldt). High contamination levels were measured in the muscles of European sea bass sampled in the coastal regions near those river mouths (e.g. Σ ICES PCB=133-10,478 μg kg(-1) lw and Hg=250-2000 μg kg(-1) dw). The Scheldt and the Seine are still among the most contaminated estuaries in Europe. Each region presented their specific contamination patterns reflecting different sources due to the input of the respective rivers. As fish and fishery products are the main contributors of the total dietary intake of organochlorinated pollutants, regular consumption of European sea bass with the reported contamination levels may represent a significant exposure route for the general human population.
• 2.63

  Impact points

  Toothed whales in the northwestern Mediterranean: insight into their feeding ecology using chemical tracers.

  Emilie Praca, Sophie Laran, Gilles Lepoint, Jean-Pierre Thomé, Antoni Quetglas, Paola Belcari, Paolo Sartor, Frank Dhermain, Denis Ody, Nathalie Tapie, Hélène Budzinski, Krishna Das

  Marine pollution bulletin. 03/2011; 62(5):1058-65.

  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... [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 (δ(13)C, δ(15)N) and organochlorines. Significantly different δ(15)N 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 δ(13)C contents between species indicated long-term habitat superposition or corroborated important seasonal migrations. Lower congener 180 concentrations (8.20 vs. 21.73 μg.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 indicate wider migrations for the former. Therefore, competition between these species seems to depend on different trophic levels and migration patterns.
• 2.72

  Impact points

  Stable isotopes of captive cetaceans (killer whales and bottlenose dolphins).

  Stéphane Caut, Sophie Laran, Emmanuel Garcia-Hartmann, Krishna Das

  The Journal of experimental biology. 02/2011; 214(Pt 4):538-45.

  There is currently a great deal of interest in using stable isotope methods to investigate diet, trophic level and migration in wild cetaceans. In order to correctly interpret the results stemming from these methods, it is crucial to understand how diet isotopic values are reflected in consumer tiss... [more] There is currently a great deal of interest in using stable isotope methods to investigate diet, trophic level and migration in wild cetaceans. In order to correctly interpret the results stemming from these methods, it is crucial to understand how diet isotopic values are reflected in consumer tissues. In this study, we investigated patterns of isotopic discrimination between diet and blood constituents of two species of cetaceans (killer whale, Orcinus orca, and bottlenose dolphin, Tursiops truncatus) fed controlled diets over 308 and 312 days, respectively. Diet discrimination factors (Δ; mean ± s.d.) for plasma were estimated to Δ(13)C=2.3±0.6‰ and Δ(15)N=1.8±0.3‰, respectively, for both species and to Δ(13)C=2.7±0.3‰ and Δ(15)N=0.5±0.1‰ for red blood cells. Delipidation did not have a significant effect on carbon and nitrogen isotopic values of blood constituents, confirming that cetacean blood does not serve as a reservoir of lipids. In contrast, carbon isotopic values were higher in delipidated samples of blubber, liver and muscle from killer whales. The potential for conflict between fisheries and cetaceans has heightened the need for trophic information about these taxa. These results provide the first published stable isotope incorporation data for cetaceans, which are essential if conclusions are to be drawn on issues concerning trophic structures, carbon sources and diet reconstruction.
• 2.91

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  Persistent organic pollutants and methoxylated PBDEs in harbour porpoises from the North Sea from 1990 until 2008: Young wildlife at risk?

  Liesbeth Weijs, Cornelis van Elk, Krishna Das, Ronny Blust, Adrian Covaci

  The Science of the total environment. 10/2010; 409(1):228-37.

  In the European North Sea, harbour porpoises are top predators with relatively long life spans and a limited capacity for metabolic biotransformation of contaminants compared to some other marine mammal species. As such, they are exposed to a mixture of persistent pollutants, such as polychlorinated... [more] In the European North Sea, harbour porpoises are top predators with relatively long life spans and a limited capacity for metabolic biotransformation of contaminants compared to some other marine mammal species. As such, they are exposed to a mixture of persistent pollutants, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), DDT and metabolites (DDXs), hexachlorobenzene (HCB) and chlordanes (CHLs) that bioaccumulate in their tissues. We report here on the levels of persistent organic pollutants and of the naturally-produced methoxylated PBDEs (MeO-PBDEs) in blubber, liver and kidney of harbour porpoise neonates (n=3), calves (n=15), juveniles (n=6) and adults (n=4) of the southern North Sea. Concentrations of almost all contaminant classes decrease slightly in all age groups over the period 1990-2008. For some classes (e.g. PCBs and DDXs) however, levels seem to increase little in harbour porpoise calves. In all animals, blubber had the highest concentrations, followed by liver and kidney, whereas liver and kidney were the preferred tissues for several compounds, such as octa- and deca-PCBs. Our data suggest that harbour porpoises calves are exposed to higher or comparable concentrations of POPs and of MeO-PBDEs and somewhat different patterns of selected POPs than adults, potentially placing them, and the entire population, at a disproportionate risk for exposure-related health effects.
• 4.80

  Impact points

  Physiologically based pharmacokinetic (PBPK) models for lifetime exposure to PCB 153 in male and female harbor porpoises (Phocoena phocoena): model development and evaluation.

  Liesbeth Weijs, Raymond S H Yang, Adrian Covaci, Krishna Das, Ronny Blust

  Environmental science & technology. 09/2010; 44(18):7023-30.

  Physiologically based pharmacokinetic (PBPK) models were developed for the most persistent polychlorinated biphenyl (PCB 153) in male and female harbor porpoises (Phocoena phocoena) to elucidate processes such as uptake, distribution, and elimination. Due to its limited metabolic capacities, long li... [more] Physiologically based pharmacokinetic (PBPK) models were developed for the most persistent polychlorinated biphenyl (PCB 153) in male and female harbor porpoises (Phocoena phocoena) to elucidate processes such as uptake, distribution, and elimination. Due to its limited metabolic capacities, long life span, and top position in marine food chains, this species is highly sensitive to pollution. The models consist of 5 compartments, liver, blubber, kidney, brain, and a compartment which accounts for the rest of the body, all connected through blood. All physiological and biochemical parameters were extracted from the literature, except for the brain/blood partition coefficient and rate of excretion, which were both fitted to data sets used for validation of the models. These data sets were compiled from our own analyses performed with GC-MS on tissue samples of harbor porpoises. The intake of PCB 153 was from milk from birth to 4 months, and after weaning fish was the main food source. Overall, these models reveal that concentrations of PCB 153 in males increase with age but suggest that, as the animals grow older, metabolic transformation can be a possible pathway for elimination as well. In contrast, the model for females confirms that gestation and lactation are key processes for eliminating PCB 153 as body burdens decrease with age. These PBPK models are capable of simulating the bioaccumulation of PCB 153 during the entire life span of approximately 20 years of the harbor porpoises.

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• 2.63

  Impact points

  Occurrence of anthropogenic and naturally-produced organohalogenated compounds in tissues of Black Sea harbour porpoises.

  Liesbeth Weijs, Krishna Das, Hugo Neels, Ronny Blust, Adrian Covaci

  Marine pollution bulletin. 05/2010; 60(5):725-31.

  Harbour porpoises are one of the three cetacean species inhabiting the Black Sea. This is the first study to report on polybrominated diphenyl ethers (PBDEs) and naturally-produced compounds, methoxylated PBDEs (MeO-PBDEs) and polybrominated hexahydroxanthene derivatives (PBHDs), in tissues (kidney,... [more] Harbour porpoises are one of the three cetacean species inhabiting the Black Sea. This is the first study to report on polybrominated diphenyl ethers (PBDEs) and naturally-produced compounds, methoxylated PBDEs (MeO-PBDEs) and polybrominated hexahydroxanthene derivatives (PBHDs), in tissues (kidney, brain, blubber, liver, muscle) of male harbour porpoises (11 adults, 9 juveniles) from the Black Sea. Lipid-normalized concentrations decreased from muscle>blubber>liver>kidney>brain for the sum of polychlorinated biphenyls (PCBs) and for the sum of PBDEs. Among the naturally-produced compounds, levels of PBHDs were higher than of MeO-PBDEs, with tri-BHD and 6-MeO-BDE 47 being the dominant compounds for both groups, respectively. Concentrations of naturally-produced compounds decreased from blubber to brain, similarly to the sum of DDT and metabolites (DDXs). Concentrations of DDXs were highest, followed by PCBs, HCB, PBHDs, PBDEs and MeO-PBDEs. Levels of PCBs and PBDEs in blubber were lower than concentrations reported for harbour porpoises from the North Sea, while concentrations of DDXs were higher.

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• 3.25

  Impact points

  Maternal transfer of chlorinated contaminants in the leatherback turtles, Dermochelys coriacea, nesting in French Guiana.

  Elodie Guirlet, Krishna Das, Jean-Pierre Thomé, Marc Girondot

  Chemosphere. 03/2010; 79(7):720-6.

  We examined the maternal transfer of organochlorine contaminants (OCs), pesticides (DDTS and HCHs) and polychlorinated biphenyls (PCBs), and the temporal variation of blood and eggs concentrations from 38 leatherback turtles (Dermochelys coriacea) nesting in French Guiana. PCBs were found to be the ... [more] We examined the maternal transfer of organochlorine contaminants (OCs), pesticides (DDTS and HCHs) and polychlorinated biphenyls (PCBs), and the temporal variation of blood and eggs concentrations from 38 leatherback turtles (Dermochelys coriacea) nesting in French Guiana. PCBs were found to be the dominant OCs with respective mean concentrations of 55.14 ng g(-1) lipid-mass for egg and 1.26 ng mL(-1) wet-mass for blood. OC concentrations were lower than concentrations measured in other marine turtles which might be due to the lower trophic position (diet based on gelatinous zooplankton) and to the location of their foraging and nesting grounds. All OCs detected in leatherback blood were detected in eggs, suggesting a maternal transfer of OCs. This transfer was shown to depend on female blood concentration for SigmaDDTs and for the most prevalent PCB congeners, since significant relationships were found between paired blood-egg concentrations. During the nesting season, OC concentrations in eggs and the percentage of lipid in eggs were found to decline in successive clutches, highlighting a process of offloading from females to their eggs and a decreasing investment of lipid from females into their clutches. OCs in eggs tended to be higher in females spending 3 years in the foraging grounds between two nesting seasons than in those spending 2 years, suggesting an impact of time spacing two breeding seasons, called remigration interval, and of location of the foraging grounds.

• Assessment of gestation, lactation and fasting on stable isotope ratios in northern elephant seals (Mirounga angustirostris)

  S. Habran, C. Debier, D. E. Crocker, D. S. Houser, G. Lepoint, J. M. Bouquegneau, K. Das

  Marine Mammal Science. 01/2010; 26:880-895.

  Abstract Effects of physiological processes such as gestation, lactation and nutritional stress on stable isotope ratios remain poorly understood. To determine their impact, we investigated these processes in simultaneously fasting and lactating northern elephant seals (Mirounga angustirostris). Sta... [more] Abstract Effects of physiological processes such as gestation, lactation and nutritional stress on stable isotope ratios remain poorly understood. To determine their impact, we investigated these processes in simultaneously fasting and lactating northern elephant seals (Mirounga angustirostris). Stable carbon and nitrogen isotope values were measured in blood and milk of 10 mother-pup pairs on days 5 and 22 of lactation. As long- and short-term integrators of diet, blood cells and serum may reflect foraging data or energy reserves from late gestation and lactation, respectively. Limited changes in isotopic signatures of maternal blood over the lactating period were highlighted. Nitrogen isotope fractionation associated with mother-to-offspring transfer of nutrients was generated between mother and offspring during gestation and lactation. This fractionation was tissue and time-specific, it varied between early and late lactation from +0.6‰ to +1.3‰ in blood cells and from +1.1‰ to nonsignificant value in serum. Therefore, if pups appear to be good proxies to investigate the female trophic ecology especially for C sources, much more caution is required in using δ15N values. Further studies are also needed to better define the relative impact of fasting and lactation on the enrichment or depletion of isotopes in different tissues.
• 4.79

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  Anthropogenic and naturally-produced organobrominated compounds in marine mammals from Brazil.

  Paulo R Dorneles, José Lailson-Brito, Alin C Dirtu, Liesbeth Weijs, Alexandre F Azevedo, João P M Torres, Olaf Malm, Hugo Neels, Ronny Blust, Krishna Das, Adrian Covaci

  Environment international. 10/2009;

  Liver samples from 51 cetaceans, comprising 10 species, stranded between 1994 and 2006 in a highly industrialized and urbanized region in Southeast Brazil, were analyzed for polybrominated diphenyl ethers (PBDEs) and methoxylated-PBDEs (MeO-PBDEs). A concentration range of PBDEs (3-5960ng/g lw) simi... [more] Liver samples from 51 cetaceans, comprising 10 species, stranded between 1994 and 2006 in a highly industrialized and urbanized region in Southeast Brazil, were analyzed for polybrominated diphenyl ethers (PBDEs) and methoxylated-PBDEs (MeO-PBDEs). A concentration range of PBDEs (3-5960ng/g lw) similar to that observed in Northern Hemisphere dolphins was found. MeO-PBDE concentrations in continental shelf (CS) dolphins from Brazil are among the highest detected to date in cetaceans (up to 250microg/g lw). Higher SigmaMeO-PBDE concentrations were measured in CS and oceanic dolphins than in estuarine dolphins. The SigmaPBDE/SigmaMeO-PBDE ratio varied significantly ranging from a mean value of 7.12 to 0.08 and 0.01 for estuarine, CS and oceanic species, respectively. A positive correlation was observed between SigmaPBDE and year of stranding of male estuarine dolphins (Sotalia guianensis), which suggests temporal variation in the exposure. Placental transfer of organobrominated compounds was also evidenced in S. guianensis.

• Modelling the habitat suitability of cetaceans: Example of the sperm whale in the northwestern Mediterranean Sea

  Praca Emilie, Gannier Alexandre, Das Krishna, Laran Sophie

  Deep Sea Research I. 04/2009; 56:648-657.
• 4.79

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  Biomagnification of naturally-produced methoxylated polybrominated diphenyl ethers (MeO-PBDEs) in harbour seals and harbour porpoises from the Southern North Sea.

  Liesbeth Weijs, Sara Losada, Krishna Das, Laurence Roosens, Peter J H Reijnders, Javier F Santos, Hugo Neels, Ronny Blust, Adrian Covaci

  Environment international. 04/2009;

  Harbour seals and harbour porpoises are top predator species from the North Sea, have long life spans and hence, are known to accumulate high levels of anthropogenic contaminants. To gain knowledge about the behaviour of naturally-produced compounds in these marine mammals, the biomagnification of n... [more] Harbour seals and harbour porpoises are top predator species from the North Sea, have long life spans and hence, are known to accumulate high levels of anthropogenic contaminants. To gain knowledge about the behaviour of naturally-produced compounds in these marine mammals, the biomagnification of naturally-produced methoxylated polybrominated diphenyl ethers (MeO-PBDEs) was assessed. The biomagnification of MeO-PBDEs (2'-MeO-BDE 68 and 6-MeO-BDE 47) was lower in harbour seals (all biomagnification factors (BMFs)<1) compared to the same age-gender groups of the harbour porpoises (all BMFs>1). This may indicate a better metabolic breakdown of MeO-PBDEs in harbour seals, as was previously suggested for polybrominated diphenyl ethers (PBDEs). In both predators, 6-MeO-BDE 47 had the highest concentrations (range: 45-483 ng/g lw and 2-38 ng/g lw for harbour porpoises and seals, respectively) compared to 2'-MeO-BDE 68 (range: 2-28 ng/g lw and 1-6 ng/g lw for harbour porpoises and seals, respectively). In general, the highest concentrations were found in juveniles, suggesting an increased biotransformation capacity with age or the influence of dilution by growth for both species. Here we show that naturally-produced brominated organic compounds can biomagnify and accumulate in North Sea top predators, although to a lesser extent than anthropogenic lipophilic contaminants, such as polychlorinated biphenyls (PCBs) or PBDEs.

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• 4.79

  Impact points

  Concentrations of chlorinated and brominated contaminants and their metabolites in serum of harbour seals and harbour porpoises.

  Liesbeth Weijs, Krishna Das, Ursula Siebert, Niels van Elk, Thierry Jauniaux, Hugo Neels, Ronny Blust, Adrian Covaci

  Environment international. 03/2009;

  Harbour seals (Phoca vitulina) and harbour porpoises (Phocoena phocoena) are top predators in the North Sea and consequently accumulate a variety of pollutants in their tissues. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and their hydroxylated metaboli... [more] Harbour seals (Phoca vitulina) and harbour porpoises (Phocoena phocoena) are top predators in the North Sea and consequently accumulate a variety of pollutants in their tissues. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and their hydroxylated metabolites (HO-PCBs and HO-PBDEs) were measured in serum of wild harbour seals (n=47) and captive harbour porpoises (n=21). Both species exhibit long life spans and do not have extreme situations, such as complete fasting during periods of lactation, in their annual cycles. For PCBs, concentrations in adult males were slightly higher than in juveniles and lowest in juvenile females. For PBDEs, juveniles have higher levels than adult males and females, probably as a consequence of lactational transfer. However, differences between these age-gender groups were not statistical significant, indicating that individual variation was limited within each species, even without knowing the feeding status of the animals. Body condition, particularly emaciation, has a major influence on the levels of chlorinated and brominated contaminants in serum. Profiles of PCBs were CB 153>CB 138>CB 187>CB 180 and CB 153>CB 138>CB 149>CB 187>CB 180 for harbour seals and porpoises respectively. For PBDEs, BDE 47 was the predominant congener followed by BDE 100 and 99 in both species. In harbour seals, concentrations of sum PCBs (median: 39,200 pg/ml) were more than 200 times higher than levels of sum PBDEs (median: 130 pg/ml) and almost 10 times higher than concentrations of sum HO-PCBs (4350 pg/ml). In harbour porpoises, concentrations of sum PCBs (median: 24,300 pg/ml) were about 20 times higher than concentrations of PBDEs (median: 1300 pg/ml). HO-PCBs were detected in only 4 harbour porpoises and this at very low concentrations. Naturally-produced MeO-PBDEs were only found in harbour porpoises at concentrations ranging from 120 to 810 pg/ml. HO-PBDEs were not found in any species. In general, harbour seals accumulate less compounds and have mostly lower concentrations than harbour porpoises possibly as a result of a better developed metabolism.

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• 4.41

  Impact points

  Erratum.

  Stéphane Caut, Sabrina Fossette, Elodie Guirlet, Elena Angulo, Krishna Das, Marc Girondot, Jean-Yves Georges

  PloS one. 02/2009; 4(7).

  [This corrects the article on p. e1845 in vol. 3, PMID: 18365003.].

• Modelling the habitat suitability of cetaceans: Example of the sperm whale in the northwestern Mediterranean Sea

  Emilie, Praca, Alexandre, Gannier, Krishna, Das, Sophie, Laran

  Deep Sea Research Part I: Oceanographic Research Papers. 01/2009; In Press.

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