References of "Das, Krishna"
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See detailMicroplastics caught in herring gill rakers: illustration by scanning electron microscopy
Collard, France ULg; Das, Krishna ULg; Parmentier, Eric ULg

Conference (2014, March 07)

Plastics are produced in huge quantity (280 million of tons in 2012) and more than 10% end up in the oceans. It is estimated that between 60 and 80% of all marine debris are plastics. Plastics are ... [more ▼]

Plastics are produced in huge quantity (280 million of tons in 2012) and more than 10% end up in the oceans. It is estimated that between 60 and 80% of all marine debris are plastics. Plastics are persistent and have accumulated in the oceans for several decades. Plastics may adverse wildlife in many ways: they can be ingested by marine vertebrates and cause internal wounds in the digestive tract. Plastics are also vectors of organic pollutants including. Once ingested, plastics may release these pollutants in the organism. Plastics present in the marine environment fragment in small pieces by mechanical stress and UV radiation leading to the so-called microplastics smaller than 5 mm. Little is known about microplastics ingestion and toxicity in planktivorous fish such as the herring, Clupea harengus. Planktivorous fish have gill rakers, which may function as a trap for microplastics. This study aims to describe and characterise microplastics present on gill rakers of the herring, Clupea harengus. Ten gill cavities were sampled in January 2013 in the Channel and the North Sea during a fishery campaign organized by the IFREMER. Gills cavities were placed in a fixating solution until preparation for scanning electron microscopy (SEM). SEM was used in order to detect microplastics which are too small to be observed by a dissection microscope, to compare them with the distance between gill rakers and to characterise the surface and the shape of microplastics. Scanning electron microscopy revealed large variety of microplastics, which lengths ranged from 0.05 to 5mm. Relationship between microplastics length and distance between gill rakers was analysed on the same branchial arch. The present study revealed the presence of microplastics in an edible species of high economic value and raise question about potential impact on the herring and its consumers, including human beings. [less ▲]

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See detailMetallothioneins pattern during ontogeny of coastal dolphin, Pontoporia blainvillei, from Argentina
Polizzi, P.S.; Romero, M.B.; Chiodi Boudet, L.N. et al

in Marine Pollution Bulletin (2014)

Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolphin is an endemic cetacean from the Southwestern Atlantic Ocean, classified as Vulnerable A3d by the IUCN ... [more ▼]

Metallothioneins are signals of metal exposure and widely used in biomonitoring. Franciscana dolphin is an endemic cetacean from the Southwestern Atlantic Ocean, classified as Vulnerable A3d by the IUCN. Metallothionein, copper and zinc in Franciscana were assessed in two geographic groups; one inhabits La Plata River estuary, anthropogenically impacted, and the other inhabits marine coastal ecosystems, with negligible pollution. Despite the environment, hepatic and renal MT concentrations were similar, but there was a declining trend from early to later developmental stages. Metallothionein K/L, Cu and Zn levels corresponded to normal reported ranges. MT was not related with Cd. Fetal concentrations were higher than its mother. These results and the health status of dolphins are suggesting that MT correspond to physiological ranges for the species, and they are closely to homeostasis of Zn and Cu, according to its ontogenetic changes. The information constitutes the first MT information on Franciscana dolphin and can be considered as baseline for the species conservation. [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 detailDevelopment of an analytical strategy to measure major selenium-containing species in juvenile turtles (Trachemys scripta scripta) by SAX-HPLC-ICP MS
Far, Johann ULg; Dyc, Christelle; Das, Krishna ULg et al

Poster (2013, July)

Sea turtles are exposed to many environmental elements such as selenium (Se). Sea turtles are listed under the Red List of threatened species by the International Union for Conservation of Nature. It is ... [more ▼]

Sea turtles are exposed to many environmental elements such as selenium (Se). Sea turtles are listed under the Red List of threatened species by the International Union for Conservation of Nature. It is thus mandatory to use low-invasive tissue collection (skin, carapace, blood ) for estimating Se exposure in these highly protected turtles. For this purpose, a biological modal Trachemys scripta scripta (or slider turtle) was selected. For two months, juvenile turtles were dietary exposed to Se by spiking the food with Selenomethionine (SeMet) or Methionine as control groups. Individuals were sacrificed after different time of exposure and tissues (skin, liver, muscle, carapace and blood) collected to perform Se speciation and determine some biological endpoints. An analytical strategy was developed to cope with the very low amount of available sample. It is briefly consisting by reduction, alkylation and proteolysis of the entire freeze-dried tissues followed by sample clean-up using ultra-filtration membrane. Then anion exchange HPLC using salt and pH gradient was developed to prevent the introduction of organic solvents, which cause severe fooling of ICP MS and avoid ultra-trace analyses of sea water in routine analysis. This method successfully achieved the detection and quantification at ppm level of expected species (i.e SeMet, selenocysteine, inorganic Se) and also unknown species but their relative amounts were time and tissues dependent. [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 detailDevelopmental changes of thyroid hormones in sheepshead minnow, Cyprinodon variegatus
Schnitzler, Joseph ULg; Mariavelle, Emeline ULg; Silvestre, Frédéric et al

Poster (2013)

The sheepshead minnow is widely used in ecotoxicological studies and such investigations have begun to focus on potential disruption of the thyroid axis. However, normal levels of thyroxin (T4) and 3,5,3’ ... [more ▼]

The sheepshead minnow is widely used in ecotoxicological studies and such investigations have begun to focus on potential disruption of the thyroid axis. However, normal levels of thyroxin (T4) and 3,5,3’-triiodothyronine (T3) and their developmental patterns are unknown. This study set out to determine the profiles of whole-body thyroxin (T4) and 3,5,3'-triiodothyronine (T3) levels during the development of sheepshead minnow from embryo to juvenile and adults. Couples of three females and two males were placed in breeding chambers designed for this experiment. More than 1000 eggs were collected and maintained in seawater. Embryos were selected under a dissection microscope and placed in incubation dishes (50 per dish) at 25°C. On day 8, embryos hatched and larvae were transferred to 1L beakers. For one week after hatching, larvae were fed on artemias and from 8 to 30 days post-hatch they were fed on flaked fish food. Embryos were sampled on day 0, 2, 4, 6 post-fertilization and larvae and juveniles were sampled every three days from day 0 to 28 days post-hatch. The pooled samples were taken from several incubation dishes and divided in three replicate batches of 30 individuals. Enzyme-linked immunoassay were used and validated for analysis of T4 and T3 after extraction from whole fish. At each sampling point 5 individuals were placed in formalin fixative for histology. Length and body mass were measured. Hatching success, gross in vivo observations, thyroid hormone levels and histology data will be determined and discussed in the framework to characterize the profiles of thyroid hormone levels during the development of sheepshead minnow from embryo to adult. This study establishes a baseline for thyroid hormones in sheepshead minnows, which will be vital for the understanding of thyroid hormone functions and in future studies of thyroid toxicants in this species. [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 detailRelationships between in vitro lymphoproliferative responses and levels of contaminants in blood of free-ranging adult harbour seals (Phoca vitulina) from the North Sea
Dupont, Aurélie ULg; Siebert, Ursula; Covaci, Adrian et al

in Aquatic Toxicology (2013), 142-143

tIn vitro culture of peripheral blood leucocytes (PBLs) is currently used in toxicological studies of marinemammals. However, blood cells of wild individuals are exposed in vivo to environmental ... [more ▼]

tIn vitro culture of peripheral blood leucocytes (PBLs) is currently used in toxicological studies of marinemammals. However, blood cells of wild individuals are exposed in vivo to environmental contaminantsbefore being isolated and exposed to contaminants in vitro. The aim of this study was to highlightpotential relationships between blood contaminant levels and in vitro peripheral blood lymphocyteproliferation in free-ranging adult harbour seals (Phoca vitulina) from the North Sea. Blood samplesof 18 individuals were analyzed for trace elements (Fe, Zn, Se, Cu, Hg, Pb, Cd) and persistent organiccontaminants and metabolites ( PCBs, HO-PCBs, PBDEs, 2-MeO-BDE68 and 6-MeO-BDE47, DDXs,hexachlorobenzene, oxychlordane, trans-nonachlor, pentachlorophenol and tribromoanisole). The samesamples were used to determine the haematology profiles, cell numbers and viability, as well as thein vitro ConA-induced lymphocyte proliferation expressed as a stimulation index (SI). Correlation tests(Bravais-Pearson) and Principal Component Analysis with multiple regression revealed no statisticallysignificant relationship between the lymphocyte SI and the contaminants studied. However, the numberof lymphocytes per millilitre of whole blood appeared to be negatively correlated to pentachlorophenol(r = −0.63, p = 0.005). In adult harbour seals, the interindividual variations of in vitro lymphocyte pro-liferation did not appear to be directly linked to pollutant levels present in the blood, and it is likelythat other factors such as age, life history, or physiological parameters have an influence. In a generalmanner, experiments with in vitro immune cell cultures of wild marine mammals should be designed soas to minimize confounding factors in which case they remain a valuable tool to study pollutant effectsin vitro. [less ▲]

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See detailHigh accumulation of PCDD, PCDF, and PCB congeners in marine mammals from Brazil: a serious PCB problem
Dorneles, Paulo R; Sanz, Paloma; Eppe, Gauthier ULg et al

in Science of the Total Environment (2013), 463-464

Blubber samples from three delphinid species (false killer whale, Guiana and rough-toothed dolphin), as well as liver samples from franciscana dolphins were analyzed for dioxins and related compounds ... [more ▼]

Blubber samples from three delphinid species (false killer whale, Guiana and rough-toothed dolphin), as well as liver samples from franciscana dolphins were analyzed for dioxins and related compounds (DRCs). Samples were collected from 35 cetaceans stranded or incidentally captured in a highly industrialized and urbanized area (Southeast and Southern Brazilian regions). Dioxin-like PCBs accounted for over 83% of the total TEQ for all cetaceans. Non-ortho coplanar PCBs, for franciscanas (82%), and mono-ortho PCBs (up to 80%), for delphinids, constituted the groups of highest contribution to total TEQ. Regarding franciscana dolphins, significant negative correlations were found between total length (TL) and three variables, ΣTEQ-DRCs, ΣTEQ-PCDF and ΣTEQ non-ortho PCB. An increasing efficiency of the detoxifying activity with the growth of the animal may be a plausible explanation for these findings. This hypothesis is reinforced by the significant negative correlation found between TL and PCB126/PCB169 concentration ratio. DRC concentrations (ng/g lipids) varied from 36 to 3006, for franciscana dolphins, as well as from 356 to 30776, for delphinids. The sum of dioxin-like and indicator PCBs varied from 34662 to 279407 ng/g lipids, for Guiana dolphins from Rio de Janeiro state, which are among the highest PCB concentrations ever reported for cetaceans. The high concentrations found in our study raise concern not only on the conservation of Brazilian coastal cetaceans, but also on the possibility of human health problem due to consumption of fish from Brazilian estuaries. [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 detailApplication of Bayesian Population Physiologically Based Pharmacokinetic (PBPK) Modeling and Markov Chain Monte Carlo Simulations to Pesticide Kinetics Studies in Protected Marine Mammals: DDT, DDE, and DDD in Harbor Porpoises
Weijs, Liesbeth; Yang, Raymond S.H.; Das, Krishna ULg et al

in Environmental Science & Technology (2013), 47

Physiologically based pharmacokinetic (PBPK) modeling in marine mammals is a challenge because of the lack of parameter information and the ban on exposure experiments. To minimize uncertainty and ... [more ▼]

Physiologically based pharmacokinetic (PBPK) modeling in marine mammals is a challenge because of the lack of parameter information and the ban on exposure experiments. To minimize uncertainty and variability, parameter estimation methods are required for the development of reliable PBPK models. The present study is the first to develop PBPK models for the lifetime bioaccumulation of p,p′-DDT, p,p′-DDE, and p,p′- DDD in harbor porpoises. In addition, this study is also the first to apply the Bayesian approach executed with Markov chain Monte Carlo simulations using two data sets of harbor porpoises from the Black and North Seas. Parameters from the literature were used as priors for the first “model update” using the Black Sea data set, the resulting posterior parameters were then used as priors for the second “model update” using the North Sea data set. As such, PBPK models with parameters specific for harbor porpoises could be strengthened with more robust probability distributions. As the science and biomonitoring effort progress in this area, more data sets will become available to further strengthen and update the parameters in the PBPK models for harbor porpoises as a species anywhere in the world. Further, such an approach could very well be extended to other protected marine mammals. [less ▲]

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See detailChanges in trace elements during lactation in a marine top predator, the grey seal
Habran, Sarah ULg; Pomeroy, P; Debier, C et al

in Aquatic Toxicology (2013), 126

Lactation in pinnipeds represents the most significant cost to mothers during the reproductive cycle. Dynamics of trace elements and their mobilization associated with energy reserves during such an ... [more ▼]

Lactation in pinnipeds represents the most significant cost to mothers during the reproductive cycle. Dynamics of trace elements and their mobilization associated with energy reserves during such an intense physiological process remains poorly understood in marine mammals. The changes in tissue concentrations of 11 elements (Ca, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, V, and Zn) were investigated in a longitudinal study during the lactation period and during the post-weaning fast period. Blood, milk, blubber, and hair samples were collected sequentially from 21 mother-pup pairs of grey seals (Halichoerus grypus) from the Isle of May in Scotland. Maternal transfer through the milk was observed for all trace elements, except for Cd. As an indicator of the placental transfer, levels in pup lanugo (natal coat) revealed also the existence of maternal transfer and accumulation of all assayed trace elements during the foetal development. The placental and mammary barriers against non-essential metal transfer to offspring appear to be absent or weak in grey seals. Examining the contamination levels showed that this grey seal population seems more highly exposed to Pb than other phocid populations (2.2 mg/kg dw of grey seal hair). In contrast, blood and hair levels reflected a lower Hg exposure in grey seals from the Isle of May than in harbour seals from the southeastern North Sea. This study also showed that trace element concentrations in blood and blubber could change rapidly over the lactation period. Such physiological processes must be considered carefully during biomonitoring of trace elements, and potential impacts that rapid fluctuations in concentrations can exert on seal health should be further investigated. [less ▲]

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See detailEffects of polychlorobiphenyls, polybromodiphenylethers, organochlorine pesticides and their metabolites on vitamin A status in lactating grey seals
Vanden Berghe, M; Weijs, L; Habran, Sarah ULg et al

in Environmental Research (2013), 120(18-26),

Polychlorobiphenyls (PCBs), polybromodiphenylethers (PBDEs) and organochlorine pesticides (OCPs) such as dichlorodiphenyltrichloroethane (DDT) and hexachlorobenzene (HCB) are considered to be endocrine ... [more ▼]

Polychlorobiphenyls (PCBs), polybromodiphenylethers (PBDEs) and organochlorine pesticides (OCPs) such as dichlorodiphenyltrichloroethane (DDT) and hexachlorobenzene (HCB) are considered to be endocrine disruptors in laboratory and wild animals. This study investigated whether these compounds and their hydroxylated metabolites (HO-PCBs and HO-PBDEs) may affect the homeostasis of vitamin A, a dietary hormone, in the blubber and serum of twenty lactating grey seals sampled at early and late lactation on the Isle of May, Scotland. The effect of naturally produced compounds such as the methoxylated (MeO)-PBDEs was also examined. Vitamin A levels in inner blubber (37 ± 9 µg/g wet weight (ww) and 92 ± 32 µg/g ww at early and late lactation, respectively) and serum (408 ± 143 ng/ml and 390 ± 98 ng/ml at early and late lactation, respectively) appeared to be positively related to ΣPCBs, ΣPBDEs and several individual PCB and PBDE congeners in inner blubber and serum. These findings may suggest an enhanced mobilisation of hepatic retinoid stores and a redistribution in the blubber, a storage site for vitamin A in marine mammals, before the onset of lactation. We also reported that serum concentrations of ΣHO-PCBs and 4-OH-CB107 tended to increase circulating vitamin A levels. Although the direction of the relationships may sometimes differ from those reported in the literature, our results are in agreement with previous findings highlighting a disruption of vitamin A homeostasis in the blubber and bloodstream following exposure to environmental pollutants. Previous studies have shown an interesting parallelism between the mobilisation and transfer of vitamin A and those of PCBs in lactating grey seals, contrary to other lipophilic molecules such as vitamin E (Debier et al. 2004; Vanden Berghe et al. 2010). The fact that vitamin A and PCBs appeared to share common mechanisms during this particular physiological state in grey seals (lactation coupled to a total fasting) may also play a role in the different relationships observed between vitamin A and lipophilic pollutants. [less ▲]

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See detailMercury in blood of free-ranging seals Phoca vitulina from the North Sea: Time-trend and association with environmental factors
Das, Krishna ULg; Brochoire, Charlène ULg; Chambosse, Mélanie et al

Conference (2012, March 27)

The harbour seal (Phoca vitulina) population from the North Sea has experienced various fluctuations these last decades due to habitat loss, prey fluctuation and pollution of the marine environment ... [more ▼]

The harbour seal (Phoca vitulina) population from the North Sea has experienced various 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 allowed blood sampling on a regular basis together with measurements of blubber thickness, body mass, sex and body length. Concentrations of total mercury (T-Hg) and other trace elements (Cd, Pb, Zn, Cu, Fe) as well as ∂13C and ∂15N values were determined by mass spectrometry in blood of 75 wild harbour seals caught in the German Wadden Sea between 1997 and 2011. ∂13C and ∂15N mean values (-17.5‰ and 18.1 ‰ respectively) were strongly similar to that measured previously in the muscle of stranded harbour seals from the Wadden Sea. In contrast, ∂15N mean value was strikingly higher than that recorded in grey seals (Halichoerus grypus) from Scotland (14.1 ‰ respectively; Habran et al. submitted.) while ∂13C values remained similar between the two seal species. These values confirmed the high trophic position of the harbour seal in the North Sea. In contrast to Cd and Pb, T-Hg in blood harbour seals reached concentrations as high as 2.1 μg.g-1 dry weight (10 times higher than the 0.21 μg.g-1 dry weight recorded for grey seals from Scotland) but depended on several factors including ∂15N values, age group and the body mass. T-Hg was detected in juveniles confirming maternal transfer to offspring and time-trend revealed no decrease of T-Hg in blood of harbour seals these last 15 years. [less ▲]

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See detailFrom field to laboratory studies: case of selenium in Chelonians
Dyc, Christelle ULg; Thomé, Jean-Pierre ULg; Das, Krishna ULg

in Proceedings of the 32nd Annual Symposium on Sea Turtle Biology and Conservation (2012, March)

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See detailThe sheepshead minnow Cyprinodon variegatus as a marine vertebrate model for investigating endocrine disrupting effects of triclosan
Schnitzler, Joseph ULg; Gauthray, Ghislain ULg; Silvestre, Frédéric et al

Poster (2012)

Zebrafish (Danio rerio) has been a prominent model in toxicology. This freshwater species present many advantages both in identifying endpoints of toxicity and in elucidating mechanisms of toxicity ... [more ▼]

Zebrafish (Danio rerio) has been a prominent model in toxicology. This freshwater species present many advantages both in identifying endpoints of toxicity and in elucidating mechanisms of toxicity. However, marine toxicologists lack such omnipotent model displaying similar advantages to zebrafish: small size, rapid breeding, and easy maintenance. We propose here the use of the sheepshead minnow Cyprinodon variegatus to define thyroid-disrupting effects of triclosan during pre-hatching development. Three females and two males were placed in each of the three breeding chambers designed for this experiment. More than 300 eggs were collected over three days and maintained in seawater with triclosan concentrations at 0, 100 ng.L-1, and 100 µg.L-1. Exposure of larvae to triclosan lasted until hatching. After hatching (six days post-spawning), 5 larvae per condition were placed in Bouin’s fixative for brain and thyroid histology. Length and body mass were measured. The body was frozen at -80oC to determine muscle thyroid hormone levels (T3 and T4), using radio-immunoassay techniques. Hatching success, in vivo observations, gross observation, thyroid hormone levels, histology will be determined and discussed in the framework of whether or not triclosan may alter thyroid metabolism during pre-hatching period of the sheepshead minnow. [less ▲]

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See detailEnvironmental factors affecting thyroid function of wild sea bass (Dicentrarchus labrax) from European coasts
Schnitzler, Joseph ULg; Klaren, Peter; Bouquegneau, Jean-Marie ULg et al

in Chemosphere (2012)

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 ... [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 (T4) and triiodothyronine (T3) 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 T4–T3 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. [less ▲]

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See detailCadmium toxicokinetics and bioaccumulation in turtles: trophic exposure of Trachemys scripta elegans
Guirlet, Elodie; Das, Krishna ULg

in Ecotoxicology (2012), 1

Ecotoxicological data in reptiles are mainly represented by field studies reporting tissues burden of wild-captured individuals but much less is known on processes of uptake, depuration, accumulation and ... [more ▼]

Ecotoxicological data in reptiles are mainly represented by field studies reporting tissues burden of wild-captured individuals but much less is known on processes of uptake, depuration, accumulation and effects of inorganic contaminants in these species. In this study, females’ Trachemys scripta elegans were exposed to cadmium (Cd) through a CdCl2 supplemented-diet with increased environmental relevant concentrations during 13 weeks and then went through a decontamination phase during 3 weeks being fed uncontaminated food. Blood and feces were collected during the three phases of the experiment and the turtles were sacrificed at the end of the experiment and organs 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 amount of Cd ingested. Assimilation efficiency in liver and kidney together was low (0.7 – 6.1 %) but did occur and Cd accumulated in a dose-dependent manner in organs in the following order of concentrations: kidney>liver>pancreas>muscle. In terms of organs burden, Cd-burden was the highest in liver followed by kidney and pancreas. The assimilation efficiency decreased as Cd ingested increased suggesting that at higher dose of Cd absorption decreased and/or depuration increased. Mineral content of the liver was modified according to Cd level with increased concentrations of zinc and iron with increasing Cd levels. Accumulation of Cd had no effects on survival, food consumption, growth or weight and length suggesting no effect of treatment on females’ body conditions. [less ▲]

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See detailHow are trace elements mobilized during the post-weaning fast in northern elephant seals?
Habran, Sarah ULg; Crocker, D; Debier, C et al

in Environmental Toxicology & Chemistry (2012), 31(10), 2354-2365

Northern elephant seal (Mirounga angustirostris) pups undergo a substantial intertissue reorganization of protein, minerals, and other cellular components during their postweaning development, which might ... [more ▼]

Northern elephant seal (Mirounga angustirostris) pups undergo a substantial intertissue reorganization of protein, minerals, and other cellular components during their postweaning development, which might entail the mobilization of associated contaminants. The authors investigated the changes in concentrations of 11 elements (Ca, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, V, and Zn) in a longitudinal study on 22 northern elephant seal pups during the postweaning fast. Slight changes in most element concentrations were observed in blood throughout the fast. Circulating levels of Hg, Se, and Cu appeared less altered during the postweaning fast than during suckling (previously measured). Despite the considerable fat utilization, element concentrations in blubber remained stable throughout the fast (except Fe), which suggests that elements are mobilized from blubber as efficiently as lipids. As indicators of the placental transfer, concentrations in lanugo hair revealed the existence of maternal transfer and accumulation of all assayed trace elements during fetal development. In addition, the new pelage, rapidly produced after weaning, appeared to be an important elimination route for toxic metals like Hg, Cd, and Pb. The high mineral content detected in pup hair suggests that this species would be more exposed to trace elements than other phocids (except Cd and Pb). This statement needs nevertheless further monitoring and toxicological studies to determine better the exposition to trace elements and its potential impact on the northern elephant seal’s health. [less ▲]

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See detailUse of Physiologically Based Pharmacokinetic (PBPK) Models in Marine Mammal Toxicology
Weijs, Liesbeth; Yang, Raymond S.H.; Das, Krishna ULg et al

in Kawaguchi, M.; Misaki, K.; Sato, H. (Eds.) et al Interdisciplinary Studies on Environmental Chemistry—Environmental Pollution and Ecotoxicology (2012)

Physiologically based pharmacokinetic (PBPK) models are mathematical models that are largely based upon the physiological characteristics of the species and the biochemical properties of the chemical of ... [more ▼]

Physiologically based pharmacokinetic (PBPK) models are mathematical models that are largely based upon the physiological characteristics of the species and the biochemical properties of the chemical of interest. They quantitatively describe and predict the kinetics of pollutants inside the body and can be of major importance for risk assessment of chemicals in marine mammals. PBPK models which consist of five compartments (liver, blubber, kidney, brain, and the rest of the body) were made for selected polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in order to address the bioaccumulation of these compounds in tissues of harbour porpoises (Phocoena phocoena). Harbour porpoises have relatively long life spans, are common cetaceans in the North Sea, a heavily polluted area, and are known to be very sensitive to pollution. Models developed for all compounds (some PCBs and PBDEs) were evaluated using existing datasets from the literature and from analyses performed by GC-MS, the latter being obtained from stranded porpoises in the Black Sea and the North Sea over a period of 18 years (1990–2008) to assess spatial and temporal trends in bioaccumulation of the respective PCBs and PBDEs. We demonstrate that PBPK models are a feasible computational approach that can be used as a non-destructive tool for predicting the chemical pollution status of the marine mammals. [less ▲]

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