Contaminant residues in seabird eggs from the Canadian Arctic. Part I. Temporal trends 1975-1998.

Concentrations of total mercury, selenium and a suite of organochlorine compounds were measured in eggs of thick-billed murres (Uria lomvia), northern fulmars (Fulmarus glacialis) and black-legged kittiwakes (Rissa tridactyla) collected on Prince Leopold Island in Lancaster Sound, Nunavut, Canada, between 1975 and 1998. Mercury levels in thick-billed murre and northern fulmar eggs increased significantly during this period while selenium concentrations decreased significantly in northern fulmar eggs. Mercury and selenium concentrations in black-legged kittiwake eggs exhibited no significant temporal trends. Concentrations of sigma PCB, sigma DDT and total chlorobenzenes decreased over time for all three species and there was a shift in the PCB congener pattern as the hexachlorobiphenyl fraction of sigma PCB increased and the lower chlorinated biphenyl fraction decreased. Total chlordane, dieldrin and mirex concentrations decreased in kittiwake eggs while no significant trends were observed for the other two species. Increases in sigma HCH levels were detected in thick-billed murre eggs but not in northern fulmar and black-legged kittiwake eggs. Levels of the beta-HCH isomer, however, increased significantly in murres and fulmars. Stable-nitrogen isotope analyses (delta 15N) indicate that the temporal trends observed for contaminant concentrations in eggs were not the result of shifts in trophic level. Changing deposition patterns of xenobiotic compounds over the summer and winter ranges of these birds provide a likely explanation for differing exposures through time.     

Levels and temporal trends (1983-2003) of persistent organic pollutants (POPs) and mercury (Hg) in seabird eggs from Northern Norway

The main objective of this study was to investigate possible temporal trends of persistent organic pollutants (POPs) and mercury in eggs of herring gulls (Larus argentatus), black-legged kittiwakes (Rissa tridactyla), common guillemots (Uria aalge) and Atlantic puffins (Fratercula arctica) in Northern Norway. Eggs were collected in 1983, 1993 and 2003. Egg concentrations of POPs (PCB congeners IUPAC numbers: CB-28, 74, 66, 101, 99, 110, 149, 118, 153, 105, 141, 138, 187, 128, 156, 157, 180, 170, 194, 206, HCB, alpha-HCH, beta-HCH, gamma-HCH, oxychlordane, trans-chlordane, cis-chlordane, trans-nonachlor, cis-nonachlor, p,p'-DDE, o,p'-DDD, p,p'-DDD, o,p'-DDT and p,p'-DDT) and mercury were quantified. Generally, POP levels decreased between 1983 and 2003 in all species. No significant temporal trend in mercury levels was found between 1983 and 2003.     

Contaminant residues in seabird eggs from the Canadian Arctic. II. Spatial trends and evidence from stable isotopes for intercolony differences

Eggs of glaucous gulls (Larus hyperboreus), black-legged kittiwakes (Rissa tridactyla), thick-billed murres (Uria lomvia) and black guillemots (Cepphus grylle) were collected from several sites throughout the Canadian Arctic. Samples were analyzed for organochlorines as well as mercury and selenium. Glaucous gulls breeding at sites in the High Arctic showed higher levels of organochlorine contamination than those in the western Low Arctic. This was likely due to dietary differences among colonies as suggested by stable isotope data, although different overwintering areas may also play a role. Levels of sigmaPCB, sigmaDDT, sigmaCHLOR, sigmaCBz and dieldrin were significantly lower in thick-billed murres from Prince Leopold Island in the High Arctic compared with colonies in the eastcrn Low Arctic. This difference was likely due to the combined effects of different atmospheric deposition patterns in the High and Low Arctic and different overwintering areas since murres from Prince Leopold Island may winter farther north than murres from the other colonies sampled. Eggs from colonies at higher latitudes generally contained higher concentrations of mercury. The trophic and dietary differences/similarities suggested by stable-nitrogen and carbon isotope data in this study were useful in explaining the spatial patterns of contaminant concentrations observed among colonies of seabirds such as the glaucous gull and the black-legged kittiwake where variation in latitudinal atmospheric deposition patterns and different overwintering grounds did not appear to be confounding factors.     

Persistent halogenated organic contaminants and mercury in northern fulmars (Fulmarus glacialis) from the Canadian Arctic

Northern fulmars from two breeding colonies in the Canadian Arctic, Cape Vera and Prince Leopold Island, were analyzed for organochlorine pesticides, PCBs, perfluorinated compounds (PFCs) and total mercury (Hg). Hepatic concentrations of organochlorines and Hg were highest in the male fulmars from Cape Vera. Perfluorooctane sulfonate (PFOS) concentrations did not vary significantly between sexes or colonies. However, concentrations of the perfluorinated carboxylates (PFCAs) were higher in fulmars from Cape Vera than Prince Leopold Island. The C₁₁-C₁₅ PFCAs averaged 90% of the PFCA profile at both colonies. Polychorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and non-ortho PCBs (NO-PCBs) were measured only in birds from Prince Leopold Island. Concentrations of PCDDs, PCDFs, NO-PCBs and Toxic Equivalents (TEQs) did not differ significantly between sexes. ΣTEQ was comprised mainly of ΣTEQ_PCDF. Concentrations of Hg and the persistent halogenated compounds reported in this study were below published toxicological threshold values for wild birds.     

Organochlorine and mercury contamination of little terns (Sterna albifrons) breeding at the western Baltic Sea, 1978-96

Between 1978 and 1996, egg and chick samples of little terns (Sterna albifrons) breeding at different colony sites along the eastern coast of Schleswig-Holstein, Germany, were annually gathered by chance in the framework of a long-term ringing programme. Analyses of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), hexachlorobenzene (HCB), hexachlorocyclohexane (HCHs), and mercury were carried out on eggs, chicks, and down (only mercury). In all matrices, pollutant concentrations decreased over the 19-year period. The mixture compositions of Sigma PCB, Sigma DDT, and Sigma HCH changed during the previous decades indicating decreasing releases of PCB mixtures, DDT, and technical HCH mixtures. The pollutant concentrations currently found in the tern eggs are compared with those of other bird species from other Baltic Sea subregions, suggesting a relatively low pollution of the Belt Sea. The temporal trends in contamination are related to international measurements and conventions on bans of pollutants. Since individually known females were recaptured up to three times, inter-individual variation in pollutant burdens could be studied. Remarkable variation among individuals as well as between breeding seasons were found that were not explainable by general temporal trends. Influences of individually and seasonally varying feeding habits on this phenomenon are discussed. Compositions of individual PCB mixtures varied in relation to total PCB concentrations found in eggs suggesting a concentration-dependent metabolization of PCBs as with other species. Amounts of particular organochlorines varied between matrices possibly indicating metabolization of low chlorinated PCBs, beta-HCH, and HCB during embryogenesis. In mercury, body detoxification via down is assumed. As indicated by eggshell parameters (thickness and index) being not related to organochlorine concentrations and being similar to that found in historical studies, respectively, effects of recent organochlorine contamination on eggshell thickness seem to be improbable. In conclusion, influences of contamination on declining little tern stocks observed in Germany are discussed. Negative influences of contamination in the 1960s and 1970s are assumed to be probable.     

Feathers as a means of monitoring mercury in seabirds: Insights from stable isotope analysis

Mercury concentrations, together with nitrogen and carbon stable isotope signatures, were determined in body feather samples from northern fulmars Fulmarus glacialis and great skuas Catharacta skua, and in different flight feathers from great skuas. There were no significant relationships between trophic status, as defined using isotope analysis, and mercury concentration in the same feather type, in either species. Mercury concentrations in body feather samples were markedly different between fulmars and skuas, reflecting differences in diet, but there was no corresponding difference in trophic status as measured through nitrogen stable isotope signatures. We conclude that mercury concentrations and stable isotope values in feathers are uncoupled, mercury concentrations apparently reflecting the body pool of accumulated mercury at the time of feather growth whilst stable isotope values reflect the diet at the time of feather growth. There were significant positive correlations between the different flight feathers of great skuas for all three parameters measured. These were strongest between primary 10 and secondary 8, suggesting that these two feathers are replaced at the same time in the moult sequence in great skuas. Stable isotope analysis of different feathers may provide a means of investigating moult patterns in birds.     

Recent changes in levels of persistent organochlorines and mercury in eggs of seabirds from the Barents Sea

Eggs of ten seabird species were collected from six regions in North Norway, Svalbard and NW Russia in 1993, and were analyzed for organochlorines (OCs) and mercury. Significant declines in levels of PCBs, p,p'-DDE, HCB, beta-HCH, gamma-HCH and oxychlordane were documented in nearly half the data set since a similar study in 1983 in six of the seabird species breeding in North Norway. Only four of the 90 paired data sets increased significantly, and the remainder remained unchanged. There was very little change in mercury levels. The decline in OCs corresponds to similar declines found in Canada and the Baltic Sea, and to declines documented in marine fish in a Norwegian fjord. They can all be attributed to the reduction in use and spread of contaminants, both in Norway and internationally. No consistent regional differences in residue levels were found.     

Temporal trend of bis(4-chlorophenyl) sulfone, methylsulfonyl-DDE and -PCBs in Baltic guillemot (Uria aalge) egg 1971-2001--a comparison to 4,4'-DDE and PCB trends

The dynamics of organohalogen contaminants and their metabolites are best studied over time by analysis of biota at high trophic levels. In this study, time trends, 1971-2001, of bis(4-chlorophenyl) sulfone (BCPS) and of methylsulfonyl-substituted metabolites of PCBs and 4,4'-DDE, were investigated in eggs of guillemot (Uria aalge) hatching in the Baltic Proper. Temporal trends of PCBs, trans-nonachlor, beta-HCH, 4,4'-DDT, and 4,4'-DDE were also assessed. Tris(4-chlorophenyl) methane (TCPMe), a 4,4'-DDT by-product, was detected in the eggs. The concentration of BCPS ranged between 2.6-0.76 microg/g on a lipid weight basis over the three decades and showed a significant 1.6% annual decrease. Three metabolites of PCBs, i.e. 3'-MeSO2-CB101, 4'-MeSO2-CB101 and 4-MeSO2-CB149, were quantified in all samples over time and showed an annual decrease of approximately 3% compared to MeSO2-DDE with a decrease of 8.9%. The methylsulfonyl-PCB and -DDE metabolites are eliminated more slowly than the persistent PCB congeners and 4,4'-DDE. Trans-nonachlor decreases by 16% compared to 19% and 9% for 4,4'-DDT and beta-HCH, respectively. The concentration of TCPMe in guillemot decreased by 8.2% per year. A linear relationship was found between TCPMe and 4,4'-DDE concentrations which supports the theory that TCPMe has an origin as a contaminant in commercial 4,4'-DDT products. The very slow decrease in BCPS concentrations is notable and remains to be explained. BCPS is still present at rather high concentrations in the guillemot eggs. The enantiomeric fraction varied between 0.27 and 0.67 which indicates less of a specific retention of the chiral MeSO2-PCBs in guillemot eggs than in grey seal tissues, for example. Independent of meta- or para-substitution of the sulfone group, the most accumulative atropisomer of each of four MeSO2-PCB pairs has been assigned an absolute R structure.     

Seabird eggs as bioindicators of chemical contamination in Chile

Seabird eggs were used as bioindicators of chemical contamination in Chile. Brown-hooded Gull (Larus maculipennis), Kelp Gull (Larus dominicanus), Trudeau's Tern (Sterna trudeaui), Neotropic Cormorant (Phalacrocorax brasilianus), and Pink-footed Shearwater (Puffinus creatopus) eggs were sampled at different breeding sites during the 1990s. Mercury and organochlorines (PCBs, DDT, HCB, HCH, and PCP) were quantified to reveal the interspecific differences, spatial and temporal trends in contamination levels. Trudeau's Tern displayed the highest levels of mercury (486 ng g(-1) wet weight). The highest sumDDT concentrations were measured in Brown-hooded Gulls (726 ng g(-1)). PCB levels were similar among the species (102-236 ng g(-1)), but the composition of the PCB mixture was different in Pink-footed Shearwaters. With the exception of the Brown-hooded Gull, all species studied presented similar and low levels of organochlorines (sumOHa). Residues of PCB and related compounds were not detected in any of the seabird eggs analyzed in Chile. Geographical variation was low, although levels of industrial chemicals were slightly higher in eggs from Concepción Bay, and agricultural chemicals in eggs from Valdivia. Also interannual variation was low, but some evidence was found of decreasing levels in gull eggs throughout the time of the study. The causes of the low levels and small variability in space and time of environmental chemicals in Chilean seabirds are discussed. We propose the use of seabirds in future monitoring of the development of chemical contamination in Chile.     

Levels of polychlorinated biphenyls, organochlorine pesticides, mercury, cadmium, copper, selenium, arsenic, and zinc in the harbour seal, Phoca vitulina, in Norwegian waters

Residue levels of the chlorinated hydrocarbons polychlorinated biphenyls (PCBs), total DDT, alpha-, beta- and gamma-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), and oxychlordane in blubber, and the elements mercury, cadmium, copper, selenium, arsenic, and zinc in liver, of 82 harbour seals, Phoca vitulina, were determined. The seals were found dead or dying in Norwegian waters during the disease outbreak caused by a morbilli virus in 1988. Of the chlorinated hydrocarbons, the highest concentrations were found of PCBs, which were 2-4 times higher than the total DDT concentrations. P,p'-DDE was the main contributor to the total DDT, and constituted about 80%. The PCB and total DDT concentrations ranged from 0.4-38 and 0.1-8.8 mg kg(-1), respectively. The mercury concentrations ranged from 0.1-89 mg kg(-1). Significantly higher mean levels of PCBs (13 mg kg(-1) and mercury (16 mg kg(-1)) were found in blubber and liver, respectively, of seals from the Southern coast of Norway, as compared to the corresponding mean levels in seals from the Oslofjord (8.8 and 4.1 mg kg(-1)), and at the Northwestern coast (5.8 and 7.9 mg kg(-1)), respectively. A significant positive correlation was found between the concentrations of selenium and mercury. When the seals were grouped according to sex and age, females of ageclass > 1 and pups of both sexes had significantly lower PCB and total DDT levels than males ageclass > 1. Significantly higher hepatic mercury levels were found in seals ageclass > 1 as compared to pups. Only low levels of the other organochlorines, cadmium and arsenic, were found. Copper and zinc were considered to be present at normal physiological levels. The present organochlorine and heavy metal concentrations gave no support to suggestions that organochlorines and heavy metal pollution may be directly involved in the observed seal deaths.     

Large-scale spatial pollution patterns around the North Sea indicated by coastal bird eggs within an EcoQO programme

To categorize the marine environmental health status, the Oslo and Paris commissions have recently formulated Ecological Quality Objectives (EcoQOs) for many ecological features including the contamination of coastal bird eggs with mercury and organochlorines. In this study, we describe spatial and temporal patterns of egg contamination around the North Sea and compared them to the EcoQOs. Concentrations of mercury, polychlorinated biphenyl (??PCB) congeners, dichlorodiphenyltrichloroethane (??DDT) and derivatives, hexachlorobenzene (HCB) and hexachlorocyclohexane (??HCH) isomers were analysed in two tern species (Sterna hirundo and Sterna paradisaea) and Oystercatcher (Haematopus ostralegus) eggs collected between 2008 and 2010 in a total of 21 sites in seven countries surrounding the North Sea. Hg, ??PCB and HCB were highest in the southern sites, while ??DDT and ??HCH concentrations were greatest in eggs from the western North Sea and the Elbe estuary. There were rarely any consistent decreases over time for any compounds. In the terns, Hg, HCB and ??HCH increased at most sites, ??PCB and ??DDT in Sweden and Norway. In the Oystercatcher, HCB and ??HCH increased at more than the half of the sites, ??PCB, ??DDT and Hg at several German sites. In the terns, Hg, ??PCB and ??DDT exceeded the EcoQO in all, HCB in most years and sites. At most sites, ??HCH fulfilled the EcoQO in some study years. In the Oystercatcher, Hg, ??PCB and ??DDT exceeded the EcoQO in all or most years and sites. HCB and ??HCH fulfilled the EcoQO in some or all years at most sites. The EcoQO was exceeded most frequently in estuaries. We conclude that EcoQOs are suitable for drawing contamination patterns of the coastal North Sea in an easily understandable manner, offering the opportunity to harmonize the EcoQOs with coordinated environmental monitoring programmes.     

Mercury and other element exposure to tree swallows (Tachycineta bicolor) nesting on Lostwood National Wildlife Refuge, North Dakota

Elevated mercury concentrations in water were reported in the prairie wetlands at Lostwood National Wildlife Refuge, ND. In order to determine whether wildlife associated with these wetlands was exposed to and then accumulated higher mercury concentrations than wildlife living near more permanent wetlands (e.g. lakes), tree swallow (Tachycineta bicolor) eggs and nestlings were collected from nests near seasonal wetlands, semi-permanent wetlands, and lakes. Mercury concentrations in eggs collected near seasonal wetlands were higher than those collected near semi-permanent wetlands or lakes. In contrast, mercury concentrations in nestling livers did not differ among wetland types. Mercury and other element concentrations in tree swallow eggs and nestlings collected from all wetlands were low. As suspected from these low concentrations, mercury concentrations in sample eggs were not a significant factor explaining the hatching success of the remaining eggs in each clutch.     

Mercury and organochlorine content of Dipper Cinclus cinclus eggs in south-west Ireland: trends during 1990-1999

A sample of 124 deserted/infertile dipper (Cinclus cinclus) eggs was collected in south-west Ireland during six seasons (1990-1994 and 1999) and analysed for mercury and organochlorines. Mercury was detected in three of the 6 years but no trend was observed. DDT occurred above the limit of detection in only two eggs, one each in 1993 and 1994. In contrast, two derivatives of DDT (DDE and TDE) were found much more commonly. DDE occurred in over 87% of eggs, while TDE contamination was less widespread and reached a maximum of 60% in 1993, with none detected in 1991 or 1999. There was no trend in occurrence of DDE or TDE across years. PCB contamination was present consistently over the 10-year period, with little change in the proportion of contaminated eggs collected over time. In all years, the lowest recorded occurrence of total PCBs was 69% expressed on a formulation basis as Arochlor 1254. PCB congeners 138, 153 and 180 dominated. The congener pattern was similar across years with the exception of 1990 when congener 118 dominated. A distinct trend of high values of contaminants was observed in 1990 and 1993. In 1990, PCB 118 was the dominant contaminant, while in 1993, HEOD, DDE, PCB 138 and PCB 153 were primary contributors to the observed result. Other contaminants (HCB, PCB 101, gamma-HCH, PCB 170 and PCB 180) showed little obvious patterns between years and occurred at relatively low levels. No pattern was observed in contaminants when eggs were grouped according to river or altitude. These data provide a baseline for organochlorine contamination levels in Irish freshwater ecosystems against which future trends can be assessed.     

Long-term trends and sources of organochlorine contamination in Canadian tundra Peregrine Falcons, Falco peregrinus tundrius

Levels of eggshell thinning, and organochlorine residues in egg contents, blood plasma of adults and juveniles, tissue samples, and prey species were determined for a population of migratory Peregrine Falcons (Falco peregrinus tundrius) breeding in the Canadian Arctic. Temporal trends were assessed by comparing data collected during 1991-1994, with data from 1982-1986, for the same population. Shells (n=54) from 1991-1994 averaged 15% thinner than eggs produced prior to the introduction of DDT. No improvement in shell thickness was detected between decades. Mean DDE residue levels in eggs showed a decline from 7.6 mg kg (1982-1986) to 4.5 mg kg (1991-1994), but there was no significant change in SigmaPCB residues. Moreover, the proportion of clutches with eggs exceeding critical SigmaPCB, DDE, and dieldrin residue levels (10%) did not change between decades. Relative to Greenland and Alaskan populations, F. p. tundrius at Rankin Inlet show high levels of organochlorine contamination and little reduction in residues over the last decade. These Tundra Peregrines continue to be exposed to organochlorines in Latin America; however, results also link relatively high levels in the study population with waterfowl species that do not leave Canada in winter.     

Biomarker responses associated with halogenated organic contaminants in northern fulmars (Fulmarus glacialis) breeding in the Canadian Arctic

We examined relationships between hepatic concentrations of halogenated organic contaminants and ethoxyresorufin O-deethylase (EROD) activity and retinoid (vitamin A) concentrations in livers, as well as retinol and thyroid hormone (TT₃, TT₄) levels in blood plasma, of northern fulmars at two breeding colonies in the Canadian High Arctic. Biomarker levels or responses did not differ significantly between males and females at either colony, nor was there any significant difference between colonies. No significant relationships were found between thyroid hormone or hepatic retinoid concentrations and any of the dioxin-like compounds or their Toxic Equivalents (TEQs) although significant positive correlations were found with plasma retinol (p < 0.03). EROD activity was significantly correlated with hepatic dioxin-like compounds and their TEQs (p < 0.001) as well as total PCBs (p < 0.01), which suggests that EROD induction occurs in northern fulmars at environmentally-relevant concentrations.     

Organochlorine and heavy metal contamination in non-viable eggs and its relation to breeding success in a Spanish population of Lesser Kestrels (Falco naumanni)

Residues of organochlorines, polychlorinated biphenyls (PCBs), and heavy metals (mercury, cadmium, lead, copper and zinc) were measured in unhatched eggs of Lesser Kestrels (Falco naumanni) collected in southern Spain in 1988-1991. Although contaminants were detected in all eggs, the amounts were generally below levels known to have negative effects on reproduction. This is consistent with the relatively high hatching rate (about 80%) in the studied population. The nestling mortality was severe, however, apparently due to starvation. It cannot be discounted that pesticides had an indirect effect on the kestrel's breeding success by reducing the populations of prey.     

Mercury Concentrations in Lentic Fish Populations Related to Ecosystem and Watershed Characteristics

Predicting mercury (Hg) concentrations of fishes at large spatial scales is a fundamental environmental challenge with the potential to improve human health. In this study, mercury concentrations were examined for five species across 161 lakes and ecosystem, and watershed parameters were investigated as explanatory variables in statistical models. For all species, Hg concentrations were significantly, positively related to wetland coverage. For three species (largemouth bass, pike, and walleye), Hg concentrations were significantly, negatively related to lake trophic state index (TSI), suggestive of growth biodilution. There were no significant relationships between ecosystem size and mercury concentrations. However, Hg concentrations were strongly, positively related to ecosystem size across species. Scores of small or remote lakes that have never been tested could be prioritized for testing using models akin to those presented in this article. Such an approach could also be useful for exploring how Hg concentrations of fishes might respond to natural or anthropogenic changes to ecosystems over time.     

Multivariate data analysis of organochlorines and brominated flame retardants in Baltic Sea guillemot (Uria aalge) egg and muscle

Concentrations of organochlorines (OCs) and brominated flame-retardants (BFRs) were determined in guillemot (Uria aalge) eggs from the island of Stora Karls? in the Baltic Sea where 10 eggs/year were collected in the years 2000, 2001 and 2002. The dominating contaminant in egg was p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) with a geometric mean (GM) concentration of 18200 ng/g lipid weight (lw). The GM concentration in egg of hexabromocyclododecane (HBCD) of 140 ng/glw, was significantly higher than that of polybrominated diphenyl ether (summation operatorPBDE) of 77 ng/glw. For the evaluation of the data multivariate data analysis techniques namely principal components analysis (PCA), partial least squares regression (PLS), soft independent modelling of class analogy (SIMCA classification), and PLS discriminant analysis (PLS-DA), were used. We investigated whether the eggs' biological characteristics co-varied with egg concentrations of OCs and BFRs, and found e.g., significant negative correlations between egg weight and concentrations of HCB and p,p'-DDE. A PLS model with analyzed BFRs as the Y matrix and OCs as the X matrix could, with varying accuracy, calculate the concentrations of BFRs in the individual egg from their concentrations of OCs (e.g., R(2)Y of 0.89 for BDE47, and of 0.50 for HBCD). Lastly, we compared the contaminant concentrations in the eggs to those in previously analyzed pectoral muscles from adult guillemots from Stora Karls?, from the year 2000. A PLS-DA model, showed that some of the contaminants (e.g., HBCD and CB28) had significantly higher concentrations in egg than in muscle, although 7 of the 14 contaminants showed no difference in concentrations between the two matrices.     

Relationships between reproductive performance and organochlorine contaminants in great black-backed gulls (Larus marinus)

The great black-backed gull Larus marinus is a top predator in subarctic and temperate marine ecosystems, and the aim of this study was to investigate if organochlorines (OCs) were related to reproductive performance in this species at the subarctic parts of the Norwegian Coast. We measured blood levels of various OCs in 53 breeding birds. The OC levels were relatively low compared to levels found in nearby arctic areas. In females, however, there was a significant positive relationship between blood concentrations of OCs, especially hexachlorobenzene (HCB) and, p,p'-dichlorodiphenyldichloroethylene (DDE), and egg laying date, and a positive relationship between the probability of nest predation and blood concentration of beta-hexachlorocyclohexane (beta-HCH), oxychlordane, and DDE. In females with high levels of OCs, especially persistent polychlorinated biphenyls (PCBs), there was also a decline in egg volume as egg laying progressed; i.e. the second and third laid egg were relatively smaller, compared to females with low OC levels. No relationships between reproductive parameters and OC levels were found in males.     

Organochlorine contaminants in eggs of the yellow-legged gull (Larus cachinnans michahellis) in the North Eastern Mediterranean: is this gull a suitable biomonitor for the region?

Levels of eight PCB congeners and thirteen organochlorine pesticides were measured in eggs sampled at four yellow-legged gull colonies from the Aegean Sea (NorthEastern Mediterranean) in 1997. There were no significant differences among colony areas in the median concentrations in any of the pollutants whereas cluster analyses did not generally reveal reasonable pollution patterns. The maximum concentrations of four congeners were found at Kinaros colony and of nine compounds were found at Lipsos colony. Fingerprints in both groups were similar in all areas. Of PCBs, congener 28, 118, 138, 180 and of pesticides beta-BHC and 2,4'-DDD were prominently dominant suggesting a particular pollution pattern in this region. Statistically significant correlations were found between most of the higher PCBs in all areas studied. The DDT metabolites correlated mostly with other OCs. We suggest that regional pollution by both groups is not adequately reflected in the eggs of this gull probably due to its extensive scavenging habits and, though information is needed from more colonies, it seems to be a poor biomonitor for organochlorines in this region.