Mercury concentrations in seabirds from colonies in the northeast Atlantic

Total mercury concentrations were determined in samples of body feathers from a range of common seabird species breeding at L»trabjarg, northwest Iceland, St. Kilda, Foula and the Firth of Forth, Scotland and Bleiksøy, Syltefjord, and Hornøy, Norway. Seabirds from L»trabjarg generally exhibited the highest mercury concentrations, with a trend of decreasing mercury concentrations in a southwest to northeast direction in seabirds at the other colonies; seabirds at Hornøy were generally found to have the lowest mercury concentrations. Some species at the Firth of Forth exhibited relatively elevated mercury concentrations compared to those at Foula and Norwegian sites. Inter-colony differences in diet were thought to be relatively small for most species and unlikely to account for the range of mercury concentrations measured in the seabirds (L»trabjarg: lowest arithmetic mean mercury concentration in common guillemots Uria aalge, 1.6 g/g, s.d.=0.6, n=45; highest arithmetic mean mercury concentration in kittiwakes Rissa tridactyla, 5.5 g/g, s.d.=1.7, n=36). The oceanic transport of mercury, together with the effects of anthropogenic inputs of mercury to the northeast Atlantic, and the removal of mercury from the water column via biological activity are discussed as influential factors determining the observed patterns of mercury concentration in seabirds.     

Mercury in three species of Suillus mushroom from some sites in Poland

Total mercury content have been determined in fruiting bodies of Variegated Bolete (Suillus variegates), European Cow Bolete (S. bovinus) and Slippery Jack (S. luteus) and in underlying to mushroom's surface layer of soil substrate collected from several spatially distant one from another sites in Poland. All three Suillus mushroom species independent of the site characterized were by small mercury content. The arithmetic mean values of mercury concentration in caps and stipes, respectively, were: 0.17 +/- 0.07-0.22 +/- 0.12 and 0.047 +/- 0.015-0.071 +/- 0.035 microg/g dry weight for Variegated Bolete; 0.28 +/- 0.11-0.79 +/- 0.40 and 0.17 +/- 0.07- 0.51 +/- 0.22 microg/g dw for European Cow Bolete, and 0.095 +/- 0.082-0.17 +/- 0.05 and 0.045 +/- 0.026- 0.070 +/- 0.026 microg/g dw for Slippery Jack. All three species of Suillus mushrooms bio-concentrated mercury (BCF > 1). European Cow Bolete bioconcentrated mercury relatively more efficiently when compared to two other species, and means of BCF value of this element in its caps ranged from 18 +/- 10 to 45 +/- 20, and in stipes from 9.4 +/- 7.5 to 29 +/- 11. A level of surface soil pollution with mercury was low and averaged from 0.017 +/- 0.003 do 0.029 +/- 0.020 microg/g dw.     

Mercury concentrations are low in commercial fish species of Lake Ziway, Ethiopia, but stable isotope data indicated biomagnification

Stable isotope ratios of nitrogen (δ¹⁵N) and carbon (δ¹³C), complemented by stomach content data, were used to assess the food web structure and trophic transfer of mercury (Hg) in four commercial fish species of Lake Ziway, Ethiopia: Nile tilapia (Oreochromis niloticus), catfish (Clarias gariepinus), Tilapia zillii, and golden carp (Carassius auratus). Total mercury (THg in mg kg⁻¹, ww) concentrations were low, with mean values of 0.033, 0.034, 0.025, and 0.011, in C. gariepinus, T. zillii, C. auratus, and O. niloticus, respectively. The relationships between mercury concentrations against total length (TL) and total weight (TW) were positive and significant in T. zillii, C. auratus, and C. gariepinus (P<0.01), but not in O. niloticus, which even showed a decreasing tendency with increase in TL and TW. Regression of log THg vs. δ¹⁵N among all fish species showed a significant correlation, indicating that mercury is biomagnifying along the food web of Lake Ziway. Isotope ratios indicated that C. gariepinus occupied the highest trophic level of the food web of Lake Ziway; but contained similar THg concentrations as T. zillii, which is located at a lower trophic level, probably due to a faster growth rate of C. gariepinus, and thus an example of biodilution.     

Mercury concentrations in fish from forest harvesting and fire-impacted Canadian Boreal lakes compared using stable isotopes of nitrogen

Total mercury (Hg) concentration was determined in several piscivorous and nonpiscivorous species of fish from 38 drainage lakes with clear-cut, burnt, or undisturbed catchments located in the Canadian Boreal Shield. Mercury concentrations increased with increasing fish trophic position as estimated using stable isotopes of nitrogen (N; r2 = 0.52, 0.49, and 0.30 for cut, reference, and burnt lakes, respectively; p < 0.01). Mercury biomagnification per thousand delta15N varied from 22 to 29% in the three groups of lakes. Mercury availability to organisms at the base of the food chain in lakes with cut catchments was higher than that in reference lakes. In cut lakes, Hg concentrations in fish were significantly related to ratio of the clear-cut area to lake area (or lake volume; r = +0.82 and +0.74, respectively, p < 0.01). Both impact ratios were, in turn, significantly correlated with dissolved organic carbon. These findings suggest that differential loading of organic matter-bound Hg to lakes can affect Hg cycling. In addition, Hg concentrations exceeded the advisory limit for human consumption (0.5 microg/g wet wt) from the World Health Organization in all top predatory species (northern pike, walleye, and burbot) found in cut and in two partially burnt lakes. Thus, high Hg concentrations in fish from forest-harvested and partially burnt lakes may reflect increased exposure to Hg relative to that in lakes not having these watershed disturbances.     

Comparison of three species of dietary fish: effects on serum concentrations of low-density-lipoprotein cholesterol and apolipoprotein in normotriglyceridemic subjects

Limited information is available comparing the effect of different species of fish on serum low-density-lipoprotein-cholesterol (LDL-C) and apolipoprotein B (apo B) concentrations. We fed 21 normotriglyceridemic males diets containing different species of fish (200 g Dover sole, Chinook salmon, or sablefish) for 18 d in a three-period crossover design. Concentrations of apo B and LDL-C rose on the salmon and sablefish diets compared with the sole diet (P = 0.02 for apo B, 0.08 for LDL-C). These increases were parallel to each other: apo B rose 14% and LDL-C rose 16% on the salmon diet and 17% and 14%, respectively, on the sablefish diet compared with the diet consumed before the study. These results suggest that the consumption of fish with a moderate amounts of n-3 fatty acids may cause a deleterious rise in LDL-C and apo B concentrations in normotriglyceridemic males.     

Organochlorines in pleuronectidae: Comparison between three tissues of three species inhabiting the Northwest Atlantic

Muscle, liver, and gonad from three species of flatfish, turbot, American plaice, and yellowtail flounder collected in the Northwest Atlantic were analyzed for a variety of organochlorine contaminants. Female flounder and plaice had lower concentrations of organochlorines than males, in all tissues. Comparing values to those previously obtained for Atlantic cod showed that concentrations in liver, the organ most often used in biomarker studies, followed the order: cod > turbot > plaice > flounder and correlated with lipid content. Muscle concentrations, which are important from a consumers perspective, followed the order: tubot > plaice > flounder > cod and were also correlated with lipids. The concentration of contaminants in gonads, the organ that informs on the future of a species were nearly undetectable. Cluster analyses demonstrated that the environmental behaviour of these contaminants can be subdivided into groups, consistent with their known chemical origin. Of the series of total and specific polychlorinated dibenzo-p-dioxins and furans studied, only tetrachlorodibenzofuran was present in most tissues.     

Bile metabolites of polycyclic aromatic hydrocarbons in three species of fish from the Severn Estuary

Six metabolites of polycyclic aromatic hydrocarbons (PAHs) were identified and quantified from the bile of 31 common eels (Anguilla anguilla), 29 European flounders (Pleuronectes flesus), and 15 conger eels (Conger conger) collected from the Severn Estuary and Bristol Channel during 1997. The bile metabolites were deconjugated by enzymatic hydrolysis and separated by reverse-phase HPLC with fluorescence detection. The major metabolite present in all fish was 1-hydroxy pyrene (75-94% of all metabolites detected) with lower proportions of 1-hydroxy chrysene (2-15%) and 1-hydroxy phenanthrene (2-8%), and small amounts of three benzo[a]pyrene derivatives (<3%). Metabolite concentrations (normalized to biliverdin content) were significantly higher in common eels than in the other two species and tended to be higher in all species at the beginning of the year than at the end. The data confirm the importance of 1-hydroxy pyrene as the key PAH metabolite in fish bile and suggest that the common eel is an ideal species for monitoring PAHs in estuarine environments.     

Mercury levels in seabirds from the Azores,Mid-North Atlantic Ocean

Levels of total mercury were determined in body feathers of 257 seabirds belonging to seven species from the Azores Archipelago, Mid-North Atlantic Ocean. Mercury levels in adult birds showed highly significant inter-specific variations. Median levels were higher in small petrels (Madeiran storm petrel=12.5 g/g; Bulwer's petrel=22.1 g/g) than in shearwaters (Little shearwater=2.1 g/g; Cory's shearwater=6.0 g/g) and terns (Roseate tern=2.0 g/g; Common tern=2.3 g/g). Such inter-specific variability is discussed in relation to biological factors that may influence mercury dynamics in birds. Intra-specific variations in mercury levels were also found. Mercury levels were significantly lower in chicks than in adults of Cory's shearwater, Roseate tern and Common tern. The levels in chick feathers were 60–70% of those in adult feathers. In Cory's shearwater and the terns (Roseate and Common combined), mercury levels decreased significantly with increasing age of chicks. Mercury levels in adult Madeiran storm petrel showed pronounced seasonal variation, being about 50% lower in Spring breeders than in Autumn breeders. Mercury levels are compared with levels reported for seabird populations of the same or related species, from a variety of regions. The use of bird feathers to monitor mercury in the marine environment is briefly discussed.     

Content of essential polyunsaturated fatty acids in three canned fish species

Three canned fish species--Pacific saury (Cololabis saira), Pacific herring (Clupea harengus) and Baltic sprat (Sprattus sprattus)--most common and popular in Russia, were analyzed for fatty acids. Special attention was paid to long-chain essential polyunsaturated fatty acids: eicosapentaenoic acid (20:5omega3) and docosahexaenoic acid (22:6omega3). Sums of eicosapentaenoic acid and docosahexaenoic acid in saury, herring and sprat were, on average, 2.42, 1.80 and 1.43 g/100 g product, respectively. Contents of these essential acids in all the canned fish species were found to be very high compared with many other fish reported in the available literature. All the canned fish appeared to be highly valuable products for human nutrition concerning the content of eicosapentaenoic and docosahexaenoic acids.     

Mercury concentrations in fish from Canadian Great Lakes areas of concern: an analysis of data from the Canadian Department of Environment database

The tissue mercury concentrations in six species of fish collected at the 17 Areas of Concern identified by the International Joint Commission on the Canadian side of the Great Lakes were analyzed using an Environment Canada database. A linear increase in mercury concentration with fish length was found, but slopes differed among locations. The temporal pattern over the period 1971-1997 differed across species in fish collected in Lake St. Clair; in at least two species there was evidence of increased mercury concentration during the 1990s that had been suggested in an earlier analysis. Areas of Concern differed significantly in observed tissue concentrations. Differences observed did not consistently parallel expectations associated with the historical presence of chlor-alkali plants in the vicinities of some locations. An attempt to correlate the fish tissue mercury concentration with the frequency of occurrence of infantile cerebral palsy at Areas of Concern was unsuccessful.