Accumulation features of trace elements in mass-stranded harbor seals (Phoca vitulina) in the North Sea coast in 2002: the body distribution and association with growth and nutrition status

Body distribution and growth- and nutritional status-dependent accumulation of 21 trace elements were investigated in harbor seals (Phoca vitulina) stranded in the North Sea coast in 2002. Higher concentrations and burdens of Mn, Se, Mo, Ag, Sn, Hg, and Bi in the liver, Cd in the kidney, As in the blubber, and Co, Sr, and Ba in the bone were observed. Significant positive correlations of hepatic Se, Mo, Ag, Cd, Sn, Hg, Tl, and Bi with standard body length were found, while significant negative relationships were detected for Mn, As, Rb, Sr, and Sb in the liver. Concentrations of Co, Se, Sr, Sn, Hg, and Bi in the liver, V, Sr, Ag, Sn, and Hg in the kidney, V, Mn, Co, Rb, Sr, Sn, Ba, and Pb in the blubber increased with decreasing blubber thickness of harbor seals, indicating enrichment of these elements in the target tissue by emaciation.     

Total body burden and tissue distribution of polyfluorinated compounds in harbor seals (Phoca vitulina) from the German Bight

Total body burden and tissue distribution of polyfluorinated compounds (PFCs) were investigated in harbor seals (Phoca vitulina) from the German Bight in 2007. A total number of 18 individual PFCs from the following groups could be quantified in the different tissues: perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonates (PFSAs) and their precursors perfluorinated sulfinates (PFSiAs), perfluorinated sulfonamides, and sulfonamido ethanols. Perfluorooctanesulfonate (PFOS) was the predominant compound in all measured seal tissues (up to 1665 ng g⁻¹ wet weight in liver tissue). The dominant PFCAs were perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA), but their concentrations were much lower compared to PFOS. The mean whole body burden in harbor seals of all detected PFCs was estimated to be 2665 ± 1207 μg absolute. The major amount of the total PFCs burden in the bodies was in blood (38%) and liver (36%), followed by muscle (13%), lung (8%), kidney (2%), blubber (2%), heart (1%), brain (1%), thymus (<0.01%) and thyroid (<0.01%). These data suggest large differences in body burden and accumulation pattern of PFCs in marine mammals.     

Selenium and mercury concentrations in harbor seals (Phoca vitulina) from central California: Health implications in an urbanized estuary

We measured total selenium and total mercury concentrations ([TSe] and [THg]) in hair (n = 138) and blood (n = 73) of harbor seals (Phoca vitulina) from California to assess variation by geography and sex, and inferred feeding relationships based on carbon, nitrogen, and sulfur stable isotopes. Harbor seals from Hg-contaminated sites had significantly greater [THg], and lesser [TSe] and TSe:THg molar ratios than seals from a relatively uncontaminated site. Males had significantly greater [THg] than females at all locations. Sulfur stable isotope values explained approximately 25% of the variability in [THg], indicating increased Hg exposure for seals with a greater use of estuarine prey species. Decreased [TSe] in harbor seals from Hg-contaminated regions may indicate a relative Se deficiency to mitigate the toxic effects of Hg. Further investigation into the Se status and the potential negative impact of Hg on harbor seals from Hg-contaminated sites is warranted.     

Polychlorinated biphenyls and chlorinated pesticides in harbor seals (Phoca vitulina concolor) from the northwestern Atlantic coast

Concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its metabolites, chlordane-related compounds (CHLs), mirex, hexachlorocyclohexane isomers (HCHs), dieldrin, and hexachlorobenzene (HCB) were determined in blubber of harbor seals (Phoca vitulina concolor) from the northwestern Atlantic coast. PCBs, DDTs, and CHLs were the major persistent organochlorines in harbor seal blubber, while mirex, HCHs, dieldrin, and HCB were minor contaminants. Highest concentrations were found in the adult males, followed by the pups, yearlings, adult females, and fetuses. DDT and PCB concentrations have declined from the high levels reported in the early 1970s, but no declines were observed in our samples over the ten-year period 1991-2001. DDT/PCB ratios were indicative of a more rapid decline of DDTs than PCBs, while ratios of p,p'-DDE/DDT were indicative of a metabolic "weathering" of DDT. The population appears to be susceptible to disease outbreaks, as evidenced by a recurrence of viral epizootics since the late 1970s. The PCB burdens in these seals are similar to levels reported in seals from polluted regions of Europe and Asia, and exceed the estimated threshold levels for adverse reproductive and immune system effects in the species.     

Accumulation of trace elements in harp seals (Phoca groenlandica) from Pangnirtung in the Baffin Island,Canada

Nineteen trace elements were determined in liver, muscle, kidney, gonads, and hair of 18 harp seals (Phoca groenlandica) from Pangnirtung in the Baffin Island, Canada. Concentrations of V, Mn, Fe, Cu, Mo, Ag, and Hg in the liver, Co, Cd, and Tl in the kidney, and Ba and Pb in the hair were significantly higher than those in other tissues. Significant positive correlations between Hg concentrations in the hair, and liver, kidney and testis imply usefulness of the hair sample for non-destructive monitoring of Hg in the harp seals. It is suggested that whereas Hg preferentially accumulates in the liver, the accumulation in other tissues is induced at higher hepatic Hg levels. In contrast, Se may not be accumulated in other tissues compared with the liver even at higher hepatic Hg levels because of the presence of excess Se for Hg detoxification in other tissues     

Mercury concentrations in the fur of steller sea lions and northern fur seals from Alaska

We compared total mercury (THg) concentrations in the fur of northern fur seals (Callorhinus ursinus) from the depleted Pribilof Islands population with those of both declining and thriving populations of Steller sea lions (Eumetopias jubatus) from Prince William Sound (PWS) and Southeast Alaska (SEA), respectively. Relatively low wet weight concentrations (ranges) of THg were detected in the fur of Steller sea lion (SSL) pups (0.90-3.14 microg/g) and juveniles (0.56-6.75 microg/g) from both areas in 1998 and 2000 compared to northern fur seal (NFS) pups (3.15-8.14 microg/g) in 2000. The mean concentration +/- SD for SSLs sampled were 1.46 +/- 0.64 microg/g for pups (n = 22) and 2.74 +/- 2.89 microg/g for juveniles (n = 6). Analyses indicated higher THg concentrations from SSL pups from PWS compared to the SEA. Mean +/- SD. THg in the NFS pups was 4.90 +/- 1.42 microg/g (n = 34) and for post-partum dams was 7.84 +/- 1.78 microg/g (n = 12).     

Accumulation of trace elements in harp seals (Phoca groenlandica) from Pangnirtung in the Baffin Island, Canada

Nineteen trace elements were determined in liver, muscle, kidney, gonads, and hair of 18 harp seals (Phoca groenlandica) from Pangnirtung in the Baffin Island, Canada. Concentrations of V, Mn, Fe, Cu, Mo, Ag, and Hg in the liver, Co, Cd, and Tl in the kidney, and Ba and Pb in the hair were significantly higher than those in other tissues. Significant positive correlations between Hg concentrations in the hair, and liver, kidney and testis imply usefulness of the hair sample for non-destructive monitoring of Hg in the harp seals. It is suggested that whereas Hg preferentially accumulates in the liver, the accumulation in other tissues is induced at higher hepatic Hg levels. In contrast, Se may not be accumulated in other tissues compared with the liver even at higher hepatic Hg levels because of the presence of excess Se for Hg detoxification in other tissues.     

Contaminants still high in top-level carnivores in the Southern California Bight: levels of DDT and PCBs in resident and transient pinnipeds

Highly industrialized areas, such as the Southern California Bight, often have high levels of contaminants in marine sediments, which can cause chronic exposure to organisms long after their use has ceased. tDDT and tPCB were analyzed in the blubber of 145 stranded pinnipeds that died at local marine mammal centers between 1994 and 2006. Resident species (California sea lion and Pacific harbor seal) had significantly higher concentrations of tDDT and tPCB than the transient species (northern elephant seal). Adult female California sea lions had significantly lower concentrations of tDDT and tPCB than pups, yearlings, and adult males. Concentrations of both tDDT and tPCB in California sea lions significantly declined over time, but did not change in northern elephant seals. Current concentrations of tDDT and tPCB in California sea lions and harbor seals are among the highest values reported worldwide for marine mammals and exceed those reported to cause adverse health effects.     

Stable isotope and trace element status of subsistence-hunted bowhead and beluga whales in Alaska and gray whales in Chukotka

Tissues of bowhead, beluga, and gray whales were analyzed for Ag, Cd, Cu, Se, Zn, THg and MeHg (belugas only). Delta15N and delta13C in muscle were used to estimate trophic position and feeding habitat, respectively. Trace element concentrations in tissues were significantly different among whale species. Hepatic Ag was higher in belugas than bowheads and gray whales. Gray whales had lower Cd concentrations in liver and kidney than bowhead and belugas and a sigmoid correlation of Cd with length was noted for all whales. Renal and hepatic Se and THg were higher in belugas than in baleen whales. The hepatic molar ratio of Se:THg exceeded 1:1 in all species and was negatively correlated to body length. Hepatic and renal Zn in subsistence-harvested gray whales was lower than concentrations for stranded whales. Se:THg molar ratios and tissue concentrations of Zn may show promise as potential indicators of immune status and animal health.     

Organochlorine contaminants in endangered Hawaiian monk seals from four subpopulations in the Northwestern Hawaiian Islands

We analyzed blubber and blood samples for organochlorines (OCs) from 158 Hawaiian monk seals (Monachus schauinslandi) at four of their six primary breeding colonies in the Northwestern Hawaiian Islands. Levels of OCs in blubber were lower in adult females compared to juveniles or adult males, evidently owing to the transfer of these lipophilic compounds to pups by pregnant and lactating females. Concentrations of SigmaPCBs and p,p'-DDE in blubber generally increased with age until seals were sexually mature and then continued to increase with age in males after puberty. Average levels of PCBs and PCB toxic equivalents (TEQs) in blubber were significantly higher in adult male and juvenile seals at Midway Atoll than the same age class of seals at the other colonies. Unlike concentrations of OCs in blubber, circulating levels of OCs in blood did not vary consistently among age classes of seals or among breeding colonies. Though the concentrations of OCs measured in Hawaiian monk seals were generally equal to or lower than those reported for other pinniped species in the North Pacific Ocean, they were high enough in a few seals to potentially affect their health.     

Levels of organochlorine compounds in an inland seal population in eastern Finland

Fourteen Saimaa ringed seals (Phoca hispida saimensis) were studied for PCB, DDT, chlordane and chlorophenol compounds in blubber, liver, muscle, heart and kidney in Lake Saimaa, eastern Finland, in 1977–1981. Both PCBs and total DDT increased on average from a good 5 mg kg^?1 in extractable fat of blubber in a new-born to a good 65 mg kg^?1 in sexually mature specimens, the maximum being 93 and 104 mg kg^?1 respectively. Concentrations of PCBs and tDDT in blubber and liver were most clearly dependent on the age and weight of the seal. Chlordanes were found in all 14 specimens (mean 0.59 mg kg^?1 in blubber), trichlorophenol in one, tetrachlorophenol in two and pentachlorophenol in all three specimens studied. Although some of the Saimaa seals had reached quite high levels of both PCBs and tDDT, the present results do not indicate that the steady decrease of the Saimaa seal population during the last two decades would have been caused by these toxins, at least not in isolation.     

Heavy metals and high pup mortality in the Saimaa ringed seal population in eastern Finland

Hair nickel, mercury, cadmium, lead and chromium concentrations were measured from still-born ringed seal pups and from other ringed seal groups from Lake Saimaa in Finland. Nickel concentration was significantly higher in the hair samples of still-born pups as compared to live-born pups and to adult seals. There was assumed to be some connection between the stillbirth of the pups and nickel concentration of the hair. Mercury concentration of the natal hair of pups was significantly higher than the mercury concentration of the first adult hair but no clear connection between stillbirth and mercury pollution was observed. No differences were observed in cadmium, lead and chromium concentrations of the hair of still-born and other ringed seal groups.     

Recent contamination by persistent organochlorines in Baikal seal (Phoca sibirica) from Lake Baikal, Russia

Blubber samples of Baikal seals pups (Phoca sibirica) collected in 2001 and 2002 were analyzed for persistent organochlorines (OCs) such as PCBs (polychlorinated biphenyls), DDTs (dichlorodiphenyltrichloroethane and its metabolites), HCHs (hexachlorocyclohexane isomers), CHLs (chlordane related compounds), TCPMe [tris(4-chlorophenyl)methane] and TCPMOH [tris(4-chlorophenyl)methanol]. The distribution pattern of OCs was in the following order: DDTs>PCBs>CHLs>HCHs>TCPMOH>TCPMe. Organochlorine concentrations and composition patterns in eight pup blubber samples (2002) analyzed in the present study were compared with the corresponding levels in juvenile Baikal seals from 1992 survey, and it was found that residue levels of OC compounds have declined during the 10 year period. In particular, concentrations of PCBs, HCHs and CHLs in seals collected in 2002 were approximately two times lower, while DDTs levels were three times lower than the corresponding levels in 1992. Furthermore, higher ratios of beta-HCH/HCHs and p,p(')-DDE/DDTs were found in 2002 samples. While comparing the OC levels with those in other seal pups it appeared that all the OC concentrations were lower than the levels in seals from coastal California known as one of the most polluted areas. PCB and DDT concentrations in the present specimens were higher than that in Arctic seal pups. The proportions of tri-, tetra-, penta- and hexachlorobiphenyls in pups captured in 2002 were higher than those in 1992. TEQ concentrations of non- and mono-ortho coplanar PCBs in Baikal seals collected in 2002 were higher than those in seals collected from some locations in the world, where human and industrial activities are extensive, suggesting potential for toxic implications of coplanar PCBs in Baikal seals.     

Spatial aspects of organochlorine contamination in northern fur seal tissues

Northern fur seals from the Pribilof Islands, Alaska (St. George Is. and St. Paul Is.) were examined for organochlorine contamination (OC) and whether the organochlorine levels differed between the populations and were at levels that may adversely affect their health. Fur seal blubber and milk samples were obtained from pups, sub-adult males, and adult females on both Pribilof Islands. These samples were analyzed for organochlorine contaminants including dioxin-like PCBs and other selected PCBs and pesticides by high performance liquid chromatography/photodiode array. Results showed that there are clear differences between the two islands in the patterns of fur seal OC distribution. Generally, these differences are confined to the PCBs with only minimal differences in the DDTs. There are also clear biological differences in the levels shown between milk, pup blubber, and sub-adult male blubber. When considering blubber, St. George Is. fur seals show higher OC levels than St. Paul Is., for both pups and sub-adults. On the other hand, milk samples from St. Paul Is. showed higher PCB levels than St. George Is. For the milk, the overall OC levels may impact the immune function of the pups, but are probably of only minimal impact to humans. However, for blubber, the overall toxic equivalency shows levels exceeding those levels recommended for human consumption at St. George Is. and approaching those levels at St. Paul Is. The concentration curves suggest that the movement of OC in and out of milk follows a complex set of reactions dependent on how the OC compounds on a congener level are associated with lipid. In fact, there is some evidence that they may not follow the lipid as closely as we had thought and that lipid levels can vary without impacting the total OC level in the milk.     

137Cs and 210Po in Pacific walrus and bearded seal from St. Lawrence Island, Alaska

The activity concentration of Cesium-137 ((137)Cs) and naturally-occurring Polonium-210 ((210)Po) were measured in the muscle tissue, kidney and liver of Pacific walrus (Odobenus rosmarus divergens) and bearded seal (Erignathus barbatus) collected by native hunters from the Bering Sea during May 1996. The mean (137)Cs concentrations in muscle, liver and kidney of Pacific walrus were 0.07, 0.09 and 0.07 Bq kg(-1) (n=5, wet weight), respectively, and 0.17, 0.10, and 0.17 Bq kg(-1) (n=2, wet weight), respectively, in bearded seal. In general, (137)Cs tissue concentrations are significantly lower than those previously reported for mammals from other regions. By comparison, (210)Po activity concentrations are more variable and appear to be higher level compared with mammal data from other regions. The mean (210)Po concentration in the muscle tissue, liver and kidney of Pacific walrus (n=5, wet weight) were 28.7, 189, and 174 Bq kg(-1), respectively. This compares with (210)Po concentration values (n=2, wet weight) of 27, 207 and 68 Bq kg(-1) measured in the muscle tissue, liver and kidney, of bearded seal, respectively. Estimated concentration factors--as defined by the radionuclide concentration ratio between the target tissue to that in sea water--were two to three orders of magnitude higher for (210)Po that those of (137)Cs. We conclude from radiological dose estimates that ingestion of (137)Cs in foods derived from walrus and seal will pose no threat to human health. This work has important implications for assessment of risks of Alaskan coastal communities concerned about the dumping of nuclear waste in the Russia Arctic.     

Tissue distribution of heavy metals in Weddell seals (Leptonychotes weddellii)

Tissue distributions of heavy metals were investigated in the Weddell seal collected around Syowa Station, Antarctica. Generally, the metal concentrations were high in liver and kidney and low in brain, blubber and skin. Fe in blood and spleen, Zn in bone, and Mn and Cd in pancreas and gastrointestinal organs were also relatively high. Wide variations of the metal concentrations in different bones were also observed. The concentrations of Fe and Cd were positively correlated with moisture content of the bones, while those of Mn and Zn increased with increase of Ca content in the bone. Majority of the metal burden in the body existed in muscle and liver. A relatively high burden of Cd was in the kidney. Based upon these results, the suitability of the tissues of a seal for ecological and toxicological comparisons is discussed.     

Heavy metal residues in tissues of marine turtles

Heavy metal concentrations in the tissues of marine turtles are presented. The most frequently monitored elements are mercury, cadmium and lead; and the tissues mainly analysed in nearly all the stranded individuals are muscle, liver and kidney. The highest mercury and cadmium levels were found in liver and kidney respectively; the majority of the lead burden existed in bones and carapace, while arsenic was present mainly in muscle tissue. Mercury occurred quite completely as methylmercury in muscle, whereas in liver the main form was the inorganic one. Arsenic was exclusively present in the metallorganic form either in muscle tissue or in liver. Metals in the eggs were mainly present in the yolk. Significantly higher concentration of mercury, copper, zinc and iron were found in yolk than albumen, while shell contained highest levels of manganese and copper. The load of trace metals in these animals strictly correlated with the species seems to depend on their different food behaviour.     

Temporal trends of mercury in marine biota of west and northwest Greenland

Temporal trends in mercury concentrations ([Hg]) during the last two to three decades were determined in liver of shorthorn sculpin, ringed seal and Atlantic walrus from northwest Greenland (NWG, 77 degrees N) and in liver of shorthorn sculpin and ringed seal from central west Greenland (CWG, 69 degrees N) during the last decade. Stable-nitrogen (delta(15)N) and carbon (delta(13)C) isotope values were determined in muscle of ringed seals to provide insight into potential trophic level changes through time. Log-linear regressions on annual median [Hg] did not reveal any temporal trend in shorthorn sculpin from CWG and NWG and walrus from NWG. In ringed seals from NWG, an increase in [Hg] of 7.8% per year was observed. When based on delta(15)N-adjusted [Hg] this rate increased to 8.5% but was still non-significant. In ringed seal from CWG no trend was found in [Hg] during the period 1994-2004. However, during the last part of the period (1999-2004) the [Hg] increased significantly. Including tissue delta(15)N values as a covariate had a marked effect on these results. The annual changes in delta(15)N-adjusted [Hg] was estimated to -5.0% for the whole period and 2.2% during the last 5 years compared to -1.3% and 12.4%, respectively, for the non-adjusted [Hg].     

Trace metals in tissues of gray whale (Eschrichtius robustus) carcasses from the Northern Pacific Mexican Coast

Samples of liver, lung, heart, muscle, and blubber tissue from the carcasses of juvenile gray whales (Eschrichtius robustus) found stranded on the coast off the Sea of Cortez, México were analyzed for a range of trace metals (Cu, Fe, Zn, Mn, Ni, Pb, and Cd). The highest concentrations of copper, iron, zinc, and manganese were found in liver; nickel and lead in heart, and cadmium in kidney. In all tissues analyzed, iron, zinc and copper were present in the highest concentrations; however, some whales also showed high levels of cadmium in the kidney which could be related to their diet. Elevated concentrations of copper were found only in the liver of one whale. In general, where low levels of iron were found in the liver, they were associated with poor nutrition. Lead, nickel, manganese and zinc levels in liver were within the normal range, indicating that these whales had not been exposed to high levels of these metals.     

Bioaccumulation of radiocaesium in Arctic seals

Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. The purpose of this investigation is to document the levels and bioaccumulation potential of radiocaesium in high latitude seal species for which data have not previously been available. The study was carried out on harp, ringed, and bearded seals caught north of the island archipelago of Svalbard (82°N) in 1999. The results are then compared with previous studies in order to elucidate factors responsible for bioaccumulation in Arctic seals. Concentrations of ¹³⁷Cs were determined in muscle, liver and kidney samples from a total of 10 juvenile and one adult seal. The mean concentration in muscle samples for all animals was 0.23±0.045 Bq/kg f.w. ¹³⁷Cs concentrations in both liver and kidney samples were near detection limits (≈0.2 Bq/kg f.w.). The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of ¹³⁷Cs in the Barents Sea region. Bioconcentration factors (BCFs) estimated for seals from NE Svalbard are low, ranging from 34 to 130. Comparing these values with reported BCFs for Greenland seals from other sectors of the European Arctic, we suggest that the combination of physiological and ecological factors on radiocaesium bioaccumulation is comparable among different Arctic seal populations. The application of this work to Arctic monitoring and assessment programs is discussed.