References of "Habran, Sarah"
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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 detailTrace elements and stable isotopes during lactation and post-weaning fast in phocids
Habran, Sarah ULg

Doctoral thesis (2012)

Haul-out periods in most phocids are particularly intense from a physiological point of view since they involve extended fasting periods associated with behaviours or processes resulting in considerable ... [more ▼]

Haul-out periods in most phocids are particularly intense from a physiological point of view since they involve extended fasting periods associated with behaviours or processes resulting in considerable energy expenditure (e.g., combat, mating, lactation, moulting). The substantial tissue reorganization during these key periods can entail the mobilization of potentially associated contaminants, such as trace elements and persistent organic pollutants. The main objectives of this study were firstly to investigate the effects of fasting, lactational, and developmental phases on trace element concentrations (Cd, Cr, Cu, Fe, Hg, Ni, Pb, Se, V, and Zn) in the northern elephant seal (Mirounga angustirostris) and the grey seal (Halichoerus grypus), and on the other hand, to assess the maternal transfer of trace elements to the offspring. Changes in the diet indicators – the carbon and nitrogen stable isotopes (δ13C and δ15N) – were also investigated throughout lactation and post-weaning fast, and their implications were developed. Different tissue samples (blood, blubber, hair, and milk) were collected repeatedly in mother-pup pairs and weaned pups in northern elephant seals and grey seals during three longitudinal fieldworks in the breeding season. Related to the remobilization of resources during lactation and pup development, short-term variations in blood concentrations of trace elements were highlighted in this study. The results imply a careful consideration of the physiological status of marine mammals when using blood in the framework of biomonitoring of trace element contamination. Although the total body burdens of trace elements decreased over lactation in adult females, circulating concentrations of some metals, like Hg, increased significantly, drawing attention to the potential adverse effects on the immune, endocrine or nervous systems in adults. Northern elephant seals and grey seals are exposed to trace elements from the first stages of development through the placenta and through the milk. Indeed, concentrations in pup hair of both species revealed a large accumulation of all assayed trace elements during the foetal development. The maternal transfer of trace elements adds to lactational transfer of others chemicals such PCBs, PBDEs, and OCPs reported in recent studies. Immunotoxic and endocrine risks related to chemical mixtures remain unclear until now and may therefore affect phocids at a crucial period of their immune development. [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 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 detailSelective transfer of persistent organic pollutants and their metabolites in grey seals during lactation
Vanden Berghe, M; Weijs, L; Habran, Sarah ULg et al

in Environment International (2012), 46

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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 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 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 detailMaternal transfer of PCBs, PBDEs and their hydroxylated metabolites in grey seal (Halichoerus grypus) from the Isle of May, Scotland
Vanden Berghe, Marie; Weijs, Liesbeth; Habran, Sarah ULg et al

in Organohalogen Compounds (2011)

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See detailAssessment of gestation, lactation and fasting on stable isotope ratios in northern elephant seals (Mirounga angustirostris)
Habran, Sarah ULg; Debier, Cathy; Crocker, Dan E. et al

in Marine Mammal Sciences (2010), 26(4), 880-895

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 ... [more ▼]

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. [less ▲]

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See detailMaternal transfer of trace metals to offspring in grey seals
Habran, Sarah ULg; Pomeroy, Paddy; Debier, Cathy et al

Conference (2010, May 25)

Marine mammals may display high heavy metal levels in their tissues, which raises the question of the importance of toxic metal transfer from mother to offspring. Some lactating female phocids fast during ... [more ▼]

Marine mammals may display high heavy metal levels in their tissues, which raises the question of the importance of toxic metal transfer from mother to offspring. Some lactating female phocids fast during the suckling period. This fasting period involves not only an important mobilization of energy reserves, but also mobilization of potentially associated contaminants. We studied maternal transfer of trace metals to offspring in the grey seal (Halichoerus grypus). Trace metal concentrations were measured in whole blood, milk and hair of mother-pup pairs in early and late lactation. Metal levels in blood decreased according to the following pattern: Fe > Zn > Se > Cu > Hg > Pb > Cr > V in mothers and pups. Cd and Ni were not detected and V, Cr and Pb levels were very low in maternal and pup blood. However, Ni and Pb levels were detected in the milk showing a transmammary transfer of these metals. Hg levels in blood and milk were higher than levels of previous metals and levels varied significantly throughout lactation. The increasing maternal levels over lactation were likely due to the remobilization of energy reserves during fasting and milk production in mothers causing a Hg release in blood. All metals were detected in hair and lanugo according to the following pattern: Fe > Zn > Hg > Cu > Se > Ni > V > Pb > Cd > Cr in mothers and Zn > Fe > Hg > Se > Cu > Pb > Ni > V > Cr > Cd in pups. Pb levels were relatively high in comparison with other phocid species. Only Hg showed a significant relationship between hair/lanugo and blood levels. This study highlights (i) a transplacental and transmammary transfer of metals in grey seals, and shows that (ii) physiological processes such as lactation and/or fasting can modify trace metal levels in the blood of mothers and pups. [less ▲]

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See detailMaternal transfer of mercury to offspring in phocids
Habran, Sarah ULg; Pomeroy, Paddy; Debier, Cathy et al

Conference (2009, June 09)

Marine mammals may display high mercury (Hg) levels in their tissues, which raises the question of the importance of toxic metal transfer from mother to offspring. Indeed, Hg could be transferred from ... [more ▼]

Marine mammals may display high mercury (Hg) levels in their tissues, which raises the question of the importance of toxic metal transfer from mother to offspring. Indeed, Hg could be transferred from mothers to fetuses via the placenta and to suckling pups via the milk, potentially affecting them during their most sensitive periods of development. Some lactating female phocids fast during the suckling period. This fasting period involves not only an important mobilization of energy reserves, but also mobilization of potentially associated contaminants. We studied and compared maternal transfer of Hg to offspring in two phocid species: the northern elephant seal (Mirounga angustirostris) from the Californian coast and the grey seal (Halichoerus grypus) from the Isle of May in Scotland. Total mercury concentrations (THg) were measured in whole blood and maternal milk of 20 mother-pup pairs of each species in early and late lactation. Methylmercury (MeHg) levels were also measured in the blood and milk of grey seals. Results indicated that Hg passed from the maternal tissue into the phocid milk. Milk showed a range of THg levels from 15 to 60 ppb (ng.g-1-wet-weight). From the first days after birth, pups displayed relatively high blood Hg levels suggesting that a Hg transfer through placenta occurred. Blood Hg levels in mothers and pups also varied significantly throughout lactation. While maternal levels doubled, pup levels were reduced by half between the beginning and the end of lactation. Remobilization of proteins and lipids during fasting and milk production in mothers might lead to a release of Hg in blood and therefore increase the levels in late lactation. On the contrary, Hg would be progressively stored in pup organs during their development. Decreasing Hg levels in pups also suggest that the Hg intake via the milk might be lower than that via the placenta. This study highlights a transplacental and transmammary transfer of Hg in both phocid populations. However, further toxicology studies are needed to help understand the potential impact of this Hg transfer. Results also showed that physiological processes such as lactation and/or fasting can modify Hg levels in the blood of mothers and pups. Therefore, such processes and body condition should be considered carefully when interpreting Hg levels in the framework of biomonitoring. [less ▲]

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See detailMaternal transfer of trace metals to offspring in northern elephant seals
Habran, Sarah ULg; Debier, Cathy; Crocker, Daniel et al

Poster (2008, October 30)

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See detailLactation effect on the trace element dynamics in northern elephant seals (Mirounga angustirostris)
Habran, Sarah ULg; Debier, Cathy; Lepoint, Gilles ULg et al

Conference (2007, November 30)

Northern elephant seals, Mirounga angustirostris, are exceptional mammals: females fast entirely during nursing while their pups may quadruple in weight over the 25-day suckling period. Females thus lose ... [more ▼]

Northern elephant seals, Mirounga angustirostris, are exceptional mammals: females fast entirely during nursing while their pups may quadruple in weight over the 25-day suckling period. Females thus lose approximately a third of body mass and produce energy-rich milk with a high fat content. Stable carbon and nitrogen isotope ratios (d13C and d15N used as diet markers) and total mercury concentrations (Hg) were measured in tissues (blood cells, serum, full blood, milk and blubber) from 20 mother-pup pairs on days 4 and 21 of lactation. A systematic difference was observed between isotopic values in blood cells and serum of the mothers, linked to diet and distinct biochemical composition between blood components. d13C differed between inner and outer blubber layers and were similar between inner blubber and milk. High Hg concentrations (up to 350 ng.g-1ww at the beginning of lactation) were found in the blood of mother elephant seals linked to their high d15N values in blood cells. Hg transfer through placenta and milk was observed between mothers and pups. A significant increase of blood Hg concentration in mothers (+285 ng.g-1ww) and a decrease in pups (-93 ng.g-1ww) were observed between days 4 and 21 of lactation. Both processes were explained by a remobilization of proteins and lipids during fasting and milk production in mothers and by a dilution of Hg in pups due to their high mass increase during this period. This study confirms that lactation modifies stable nitrogen isotope ratios in tissues, as well as mercury levels in blood from mothers and pups, and highlights the existence of a transplacental and transmammary transfer of mercury in northern elephant seals. Therefore, physiological processes and body condition should be considered carefully when interpreting stable isotope ratios and Hg concentrations in the framework of biomonitoring. [less ▲]

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See detailMercury in the blood of free ranging pinnipeds: levels, sources of variation, toxicocinetic and potential impact using an in vitro model
Das, Krishna ULg; Gillet, Marie-Claire ULg; Habran, Sarah ULg et al

Conference (2007)

Despite 30 years of international regulations, Hg levels in marine mammals have not decreased. Various environmental models even suggest a rise of mercury in the biota during the next decades, linked to ... [more ▼]

Despite 30 years of international regulations, Hg levels in marine mammals have not decreased. Various environmental models even suggest a rise of mercury in the biota during the next decades, linked to climate change. The objective of this study is (1) to assess Hg levels in blood samples of free-ranging pinnipeds, (2) to understand level variation during different periods of life (gestation, lactation, fasting) and potential impact on lymphocytes using a preliminary in vitro model (peripheral blood mononuclear cells, PBMC). Blood samples were collected from harbour seals (Phoca vitulina n= 22) from the North Sea and from elephant seals from the Californian coast (Mirounga angustirostris 12 females and 12 pups). Harbour seal PBMC were isolated, set in medium culture and contaminated with methyl-Hg (1 µM). Biological tests and proteomic assay were realized on control and contaminated PBMC. Hg levels were from the same order of magnitude for the two species despite two different lifestyles and habitats: from 40 to 590 ng.g-1 fw in harbour seal and from 63 to 919 ng.g-1 fw in elephant seal. Hg concentrations in the blood depend upon several factors such as body weight, fasting and lactation duration for mothers and pups. After 21 days of lactation, female elephant seals doubled their blood Hg levels (from 308 to 593 ng.g-1fw) while a decrease is observed for pups. This increase is linked to mobilization from blubber and muscle during fasting associated to lactation. Cell model revealed an in vitro effect of Hg even at low concentration (1µM). Number of PBMC, viability, metabolic activity, DNA and RNA synthesis were reduced in vitro suggesting deleterious effects of Hg in concentrations encountered in free-ranging pinnipeds. Knowing that Hg methylation in the ocean is linked to temperature, one can wonder on Hg levels (and effects) in pinnipeds during the next decades. [less ▲]

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See detailLactation effect on stable isotope ratios and mercury levels in the blood of northern elephant seals
Habran, Sarah ULg; Debier, Cathy; Lepoint, Gilles ULg et al

Poster (2006, October 27)

Female northern elephant seals, Mirounga angustirostris, fast entirely during nursing while their pups may quadruple in weight over the 25-day suckling period. Stable carbon and nitrogen isotope ratios ... [more ▼]

Female northern elephant seals, Mirounga angustirostris, fast entirely during nursing while their pups may quadruple in weight over the 25-day suckling period. Stable carbon and nitrogen isotope ratios (d13C and d15N used as diet markers) and total mercury concentrations (Hg) were measured in tissues (blood cells, serum, full blood, milk and blubber) from 20 mother-pup pairs on day 4 and 21 of lactation. A systematic difference was observed between isotopic values in blood cells and serum of the mothers, linked to diet and distinct biochemical composition between blood components. d13C differed between inner and outer blubber layers and were similar between inner blubber and milk. High Hg concentrations (up to 350 ng.g-1 ww at the beginning of lactation) were found in the blood of mother elephant seals linked to their high d15N values in blood cells. Hg transfer through placenta and milk was observed between mothers and pups. A significant increase of blood Hg concentration in mothers (+285 ng.g-1ww) and a decrease in pups (-93 ng.g-1ww) were observed between days 4 and 21 of lactation. Both processes were explained by a remobilization of proteins and lipids during fasting and milk production in mothers and by a dilution of Hg in pups due to their high mass increase during this period. To conclude, physiological processes and body condition should be considered carefully when interpreting stable isotope ratios and Hg concentrations in the framework of biomonitoring. [less ▲]

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