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.     

Residues of chlorinated pesticides in the eggs of Karelian birds, 1989-90

Eggs (n = 52) of four aquatic bird species (Larus canus, Larus argentatus, Larus ridibundus, Sterna hirundo) and crow (Corvus cornix), collected in Southern Karelia in 1989 and 1990, contained DDE and lindane. The highest mean levels of these pollutants were in herring gull eggs and in common tern eggs. The lowest mean levels of pesticides were in crow eggs. In all eggs, DDE concentrations were lower than the critical threshold and it seems, cannot influence reproductive success.     

Organochlorine contamination in bird's eggs from the Danube Delta

In this study we report the levels of organochlorine compounds in eggs of aquatic birds from the Danube Delta, a major European wetland. The eggs were collected in 1997 and belonged to the following species: the mallard (Anas platyrhynchos), the greylag goose (Anser anser), the mute swan (Cygnus olor), the coot (Fulica atra), the glossy ibis (Plegadis falcinellus), the spoonbill (Platalea leucorodia), the little egret (Egretta garzetta), the night heron (Nycticorax nycticorax), the grey heron (Ardea cinerea), the great white egret (Egretta alba), the red-necked grebe (Podiceps griseus), the Dalmatian pelican (Pelecanus crispus), the Pygmy cormorant (Phalacrocorax pygmaeus) and the common cormorant (Phalacrocorax carbo). Dichlorodiphenyltrichloroethane (DDT) levels were higher in eggs of the little egret, the great white egret, the cormorant and the Pygmy cormorant with respect to the other species (48,399, 13,613, 12,400 and 10,417 ng/g dry wt., respectively). Hexachlorobenzene (HCB) levels were lower than 1393 ng/g dry wt. in all species while polychlorinated biphenyl (PCB) concentrations in the Pygmy cormorant (2565 ng/g dry wt.) were higher than in the other species. The toxicity evaluation was based on 2,3,7,8-TCDD toxic equivalent factors (TEF) and non-ortho PCB congeners contributed much more than mono-ortho PCBs in most of species. A further aim of this study was to evaluate the possible differences of organochlorine levels in bird eggs collected in the same area in 1982 and in 1997; generally speaking the levels detected in the latter period were lower than those detected in the earlier one.     

Assessing breeding potential of peregrine falcons based on chlorinated hydrocarbon concentrations in prey

Peregrine falcons (Falco peregrinus) now breed successfully in most areas of North America from which they were previously extirpated. The loss during the mid-part of the last century of many of the world's peregrine populations was largely a consequence of impaired reproduction caused by the effects of DDE on eggshell quality and embryo hatchability. Population recovery has been attributed to re-introduction efforts, coupled with regulatory restrictions on the use of organochlorine pesticides. Peregrines have not returned to breed in some areas, such as the Okanagan Valley of British Columbia. That region has been extensively planted in fruit orchards which were treated annually with DDT during the early 1950s to the 1970s. Ongoing contamination of avian species, including potential peregrine prey, inhabiting orchards has been documented. In response to an initiative to release peregrines around the city of Kelowna in the Okanagan Valley, we collected potential peregrine prey species and analyzed whole bodies for chlorinated hydrocarbon residues. We used a simple bioaccumulation model to predict concentrations of DDE in peregrine eggs using concentrations in prey and estimates of dietary makeup as input. Peregrines would be expected to breed successfully only if they fed on a diet primarily of doves. Feeding on as little as 10% of other species such as starlings, robins, gulls and magpies would produce DDE concentrations in peregrine eggs greater than the threshold of 15 mg/kg. We also estimated the critical concentration of DDE in total prey to be about 0.5 mg/kg, one half of the previous most conservative criterion for peregrine prey. Concentrations of dieldrin and PCBs in peregrine prey are less than suggested critical levels.     

Organochlorine contaminants in cormorant, darter, egret, and ibis eggs from South Africa

During the last 15 years, no research has been published on the levels of pesticides in bird eggs from South Africa, despite the high levels found previously. We analysed eggs from African darter, cattle egret, reed cormorant, African sacred ibis, as well as single eggs from some other species, and found HCB, DDTs, HCHs, chlordanes and PCBs at detectable levels. The presence of mirex in all species was unexpected, since this compound was never registered in South Africa. It also seemed as if terrestrial feeding birds had higher DDE:PCB ratios when compared with aquatic feeding birds. Except for chlordane, the African darter eggs had the highest levels of all other compounds (mean 370 and 300 ng g(-1) ww Sigma pesticides and Sigma PCBs, respectively). Multivariate analysis clearly distinguished the aquatic and terrestrially feeding birds on pollution profile. The African darter (aquatic feeding) and the cattle egret (terrestrial feeding) would be good indicator candidates. Eggshell thinning was detected in the African darter, and was associated with most of the compounds, including DDE and PCBs. We raise a concern that generally longer living birds in warmer climates, laying fewer eggs per clutch, might be at increased risk when compared with trophically similar birds exposed to equivalent levels of pollution in colder climates. Given the scarcity of water and the high biodiversity in Southern Africa, climate change will exert strong pressure, and any additional anthropogenic contamination at levels that can cause subtle behavioural, developmental and reproductive changes, can have serious effects.     

PCBs, TEQs and plasma retinol in grey heron (Ardea cinerea) hatchlings from two rookeries in Norway.

Fish-eating birds are particularly subject to accumulation of persistent organic pollutants, and polychlorinated biphenyls (PCBs) have been shown to constitute a major hazard for this group of birds. Grey heron (Ardea cinerea) hatchlings from two rookeries were applied as sentinel species to study PCB burdens in coastal ecosystems in mid Norway and north Norway, and plasma retinol and dioxin-equivalencies (sigmaTEQ) were applied to assess toxic effects of the PCB-burdens. The results show that grey herons appear to be amongst the fish-eating birds in Norway that are accumulating PCBs to the largest extent. There were no differences in sigmaPCB or sigmaTEQ in the yolk of grey heron hatchlings from the two rookeries and, accordingly, none in plasma retinol concentrations either. Furthermore, plasma retinol concentrations could not be related to sigmaPCB or sigmaTEQ. Thus, it seems that exposure levels are below the threshold for gross retinoid-related effects in grey heron hatchlings. There are also indications that the grey heron could be relatively insensitive to retinoid-related effects of PCBs. In the hatchlings with the highest pollutant levels, sigmaTEQs were in the lower range of levels that have been associated with reduced hatching success in other fish-eating bird species.     

Organochlorine contaminants and eggshell thinning in grebes from prairie Canada

Eggs of five species of grebe were collected from Manitoba, Saskatchewan and Alberta during 1982-1987: red-necked (Podiceps grisegena), horned (P. auritus), eared (P. caspicus), western (Aechmophorus occidentalis) and pied-billed (Podilymbus podiceps). DDE and PCBs were present in all samples analyzed, whereas dieldrin, mirex and oxychlordane were occasionally present at low levels. Mercury was present at low levels in all samples for which it was analyzed. Red-necked grebes nesting in Manitoba had the highest contaminant levels and, assuming that contaminant burdens were accumulated principally on the wintering grounds, the mean PCB:DDE ratio (3.1) indicated that these birds and those from sites in central and eastern Saskatchewan probably wintered on the Atlantic coast. Overall low contaminant levels and a low mean PCB:DDE ratio (1.4) in the eggs of red-necked grebes breeding in Alberta and western Saskatchewan suggested that these birds wintered on the Pacific coast. A similar pattern was apparent in horned and eared grebes. Concentrations of DDE and PCB were both significantly correlated with Ratcliffe index (shell thickness), and were strongly correlated with each other. Ratcliffe indices were determined for historical collections of red-necked grebe eggs. Eggshell thickness of grebes nesting in Manitoba declined significantly during the years following the introduction of DDT (post-1947) and has only recovered partially since it was banned in 1972. The Alberta-breeding population did not appear to have undergone any significant decrease in shell thickness.     

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.     

Residues of organochlorine pesticides,polychlorinated biphenyls and heavy metals in the eggs of predatory birds from Doñana National Park (Spain), 1980–1983

Abstract

Organochlorine pesticides and heavy metal residues were determined in 54 eggs of five species of predatory birds collected at Doñana National Park (Spain) during the nesting season between 1980 and 1983. The species analyzed were the imperial eagle (Aquila heliaca), the red kite (Milvus milvus), the black kite (Milvus migrans), the hobby (Falco subbuteo) and the booted eagle (Hieraetus pennatus). DDE, DDT and PCBs were detected in all samples. α‐HCH, α‐HCH, aldrin, dieldrin, heptachlor, heptachlor epoxide, TDE and dichlorobenzophenone were also detected but less frequently. The DDE content of eggs decreased in the period between 1972/1976 and 1980/1983, but the PCBs contents were stable. The declines are attributed to the restrictions on the use of DDT in most countries. Mercury, lead, cadmium, copper and zinc were detected in all samples. The levels of organochlorine pesticides, PCBs and heavy metals in these Falconiforme eggs are generally below the levels known to cause direct effects on survival or reproduction of birds.     

Reproductive success and chlorinated hydrocarbon contamination of resident great blue herons (Ardea herodias) from coastal British Columbia,Canada, 1977 to 2000

Over the period 1977-2000, eggs of Pacific great blue heron (Ardea herodias fannini) were collected from 23 colonies along the southern coast of British Columbia, Canada, and analyzed for persistent organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs). Concentrations of OC pesticides in eggs declined sharply in the late 1970s, after which there were minimal changes. The sums of PCB congeners were not reduced appreciably during the 1980s and 1990s, but Aroclor 1260 concentrations suggested a sharp decline in PCB contamination of eggs in the late 1970s, similar to that shown for OC pesticides. Eggs collected along or near the Fraser River delta showed higher levels of most pesticides compared to other monitored colonies. Although the delta lands support a long-standing agricultural economy, the primary factors influencing OC levels in the delta colonies were thought to be driven by estuarine processes. We suggest two possible influencing factors were: 1) a greater rate of bioaccumulation in the estuary due to the deposition of particulates collected over a vast area encompassed by the Fraser River watershed; or 2) a higher rate of biomagnification in the estuary due to species differences at lower trophic levels of the heron food chain. Eggs from urban colonies contained higher levels of PCBs. The congener pattern was not clearly different from that observed in less contaminated eggs from rural and pulp mill-influenced colonies, except that colonies in Vancouver had greater proportions of PCB-66, suggesting a local source of Aroclor 1242. Productivity in the coastal heron colonies was highly variable over the period of study, with 71% of recorded colony-wide reproductive failures occurring in colonies near pulp mills. However, the predominant factors influencing reproductive success were probably disturbance by humans and bald eagles, combined with loss and degradation of nesting habitat, and not sublethal toxicity.     

Possible chemical causes of skeletal deformities in grey heron nestlings (Ardea cinerea) in North Nottinghamshire, UK

Dead and deformed grey heron (Ardea cinerea) chicks were reported at a large heronry in North Nottinghamshire, UK between 1996 (when systematic visits to the heronry started) and 2002. Many of the birds died for no obvious reason but deformities in others included multiple fractures of the tarsus and tibia and metacarpal bones (angel wings). This study aimed to investigate possible chemical causes of these deformities. Analysis of eggs and nestling tissue for a range of metals showed no levels of concern and no significant differences between unaffected and deformed birds. However, the levels of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) detected in affected heron nestlings in 2002 and in eggs taken from nests in 2003 were sufficiently high to suggest that this may be the underlying cause of the deformities, possibly due to effects on deposition of calcium in bone. Further work is underway to identify where the parent birds of the affected nestlings are feeding and identify the possible source of the pollution.     

Levels of DDT and PCB's in different stages of life cycle of the Arctic tern Sterna paradisaea and the herring gull Larus argentatus

∑DDT and PCB levels were analysed in samples of arctic terns and herring gulls collected in the archipelago of southwestern Finland. Special attention was paid to the levels at various stages of the life cycle and in different sexes. The levels were nearly ten times higher in the herring gull. The highest loads were found in adult birds and in newly hatched chicks but the levels were much lower (only 7–12 % in the herring gull) in chicks just before fledgling. The levels in young gulls remained low until the end of August at least. Therefore it is plausible that the high levels found in adult gulls are a consequence of their wintering in the southern Baltic.The levels of ∑DDT and PCB residues were significantly lower in female arctic terns than in male terns. Differences between the sexes were small in the herring gull. Thus it is possible that the female of the arctic tern is able to release pollutants, especially PCB residues, more effectively into eggs than the female of the herring gull. The biochemical mechanisms involved are not clear but a possible explanation may be different lipoprotein structures in the eggs of the species.     

Trace elements and chlorinated hydrocarbons in eggs of Pelecanus crispus, a world endangered bird species nesting at Lake Mikri Prespa, North-western Greece

Eggs of the Dalmatian pelican, Pelecanus crispus, collected from 1984 to 1986 at Lake Mikri Prespa, north-western Greece, contained residues of trace elements and PCBs at low concentrations, and of DDE at rather high concentrations. DDE is negatively related to eggshell thickness. Eggshell thickness was reduced by 12-20% in comparison with the pre-1947 (before DDT use) eggshell thickness. However, this decrease did not affect the reproductive success of this species. The main fish species eaten by the Dalmatian pelican at Lake Mikri Prespa were analyzed for pollutants. All the fish contained low concentrations of residues. The contribution of the diet while the birds are on the wintering grounds is unknown. Recommendations for a monitoring programme of pollutants in eggs of the Dalmatian pelican, a world-endangered species, are proposed.     

Blood biomarkers and contaminant levels in feathers and eggs to assess environmental hazards in heron nestlings from impacted sites in Ebro basin (NE Spain)

Blood biomarkers and levels of major pollutants in eggs and feathers were used to determine pollution effects in nestlings of the Purple Heron Ardea purpurea and the Little Egret Egretta garzetta, sampled on three Ebro River (NE Spain) areas: a reference site, a site affected by the effluents of a chlor-alkali industry and the river Delta. The two impacted heron populations showed mutually different pollutant and response patterns, suggesting different sources of contamination. In the population nesting near the chlor-alkali plant, elevated levels of hexachlorobenzene (HCB) and polychlorobiphenyls (PCBs) in eggs, and mercury in feathers in A. purpurea chicks were related with reduced blood antioxidant defenses and increased levels of micronuclei. In Ebro Delta, high levels of plasmatic lactate dehydrogenase in A. purpurea chicks and high frequency of micronuclei in blood of both species were tentatively associated with intensive agricultural activities taking place in the area. These results provide the first evidence of a biological response in heron chicks to the release of pollutants at a chlor-alkali plant.     

Environmental contaminants and reproductive success of great blue herons Ardea herodias in British Columbia, 1986-1987

In 1986, eggs were collected and productivity estimated at four great blue heron (Ardea herodias) colonies on the coast of British Columbia. Polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were present in all eggs in a qualitatively similar pattern among colonies. PCDD levels were significantly elevated at a colony near a kraft pulp mill at Crofton on Vancouver Island, although there was no correlation between the number of young raised in a nest and levels of either PCDDs, PCDFs, PCBs, organochlorine pesticides or mercury. In 1987, heron productivity was normal at three colonies, while the colony at Crofton failed to raise any young. A normal complement of eggs were apparently laid in about 57 nests, but during incubation they were destroyed and the broken eggshells were found in and beneath the nests. Analysis of eggs salvaged from nests showed that 2378-TCDD levels were about three times higher in 1987 than in 1986. At a colony in Vancouver, 2378-TCDF levels were significantly higher in 1987 than 1986 eggs. Levels of organochlorine pesticides and total mercury in eggs were generally low; highest residue levels were found in two mainland colonies, particularly at one adjacent to an agricultural area. Total PCB levels were low and did not differ significantly among locations. Analysis of PCB congener ratios indicated different sources of PCBs. Regurgitated prey samples collected in 1986 from four locations had generally low levels of PCDD, PCDF, mercury, lead and cadmium contamination.     

Heavy metals and metalloids in egg contents and eggshells of passerine birds from Arizona

Concentrations of inorganic elements were determined in eggs of passerine birds including the endangered southwestern willow flycatcher (Empidonax traillii extimus) from four regions in Arizona. The main aim of the study was to determine the distribution of metals in egg contents and eggshells, with emphasis on the deposition of Sr in eggshells. Seventy eggs of 11 passerine species were collected at four nesting locations during 2000. Aluminum, Ba, Cr, Cu, Mn, Se, Sr, and Zn, were detected primarily in egg contents of all bird species. Arsenic, Ni, Pb, and V were detected primarily in eggshells. A proportion of most inorganic elements accumulated in the eggshell. Concentrations of Ba, Cu, Mn, Se, Sr, and Zn in egg contents and As, Ba, Cu, and V in eggshells of yellow-breasted chats (Icteria virens) were similar among locations. However, concentrations of Mn, Ni, Sr, and Zn in eggshells were significant different among locations. Except for Cu, Mn, Se, and Zn, concentrations of inorganic elements were 2-35 times greater in eggshells than in eggs. Most concentrations of metals and metalloids in eggs and eggshells of all the bird species were below levels known to affect reproduction or that have other deleterious effects. However, I found somewhat elevated concentrations of Sr in eggshells (highest MEAN=1505 microg/g dw, n=3) of yellow-breasted chats and willow flycatchers, and in egg contents of yellow warblers (Dendroica petechia) and song sparrows (Melospiza melodia). Whether current observed concentrations of Sr in eggshells are affecting nesting birds in Arizona remains to be determined. Strontium and other metals could be associated with lower hatching success in some areas. This study shows that a proportion of many inorganic elements accumulates in the eggshell and that the potential effects on the proper structure and functioning of the eggshell should not be ignored.     

Polychlorinated biphenyls and organochlorine pesticides in various bird species from northern China

Little data are available on organochlorine contamination in Chinese terrestrial birds of prey. This study examined the presence of PCBs, DDTs and other organochlorine pesticides in various raptors from northern China. DDE exhibited the highest concentrations among targeted compounds. Greatest levels (23.5-1020 mg/kg lipid weight) were observed in Eurasian sparrowhawks. This may be due to their stopover in southeastern China, where high DDT and dicofol applications have been documented. Residential kestrels exhibited much lower DDE, but similar PCB and HCH concentrations. ΣTEQs and PCB-126/-77 concentration ratios exhibited significant positive correlations with ΣPCB concentrations, respectively. Similar results were also demonstrated by a meta-analysis of previously published data across avian species. Possible hepatic sequestration of coplanar PCB-77, -126, -169 and -118 was observed as liver TEQs increased in Eurasian sparrowhawks. These observations may indicate an induction of CYP1A enzymes, as a result of elevated contamination in some species.     

Accumulation of organochlorine contaminants in double-crested cormorants

Cormorant eggs and lipid samples from juvenile Cormorants were analyzed for 14 organochlorine contaminants. Low concentrations (geometric mean < 0.05 microg/g) of hexachlorobenzene (HCB), lindane, oxy-chlordane, heptachlor epoxide, dieldrin, endrin, mirex, DDD and DDT in eggs primarily reflected the wintering-ground origin of organochlorine contaminants. Overall geometric mean concentrations of DDE and PCBs in Cormorant eggs were 3.90 and 2.22 microg/g egg respectively, and would not affect reproduction or eggshell thickness. Eggshells averaged 0.44 mm in thickness and no correlation (r2 = 0.17) with log-transformed DDE residues in Cormorant eggs was evident. Only DDE and PCBs were detected in lipid samples from 5- to 8-week-old Cormorants (geometric mean approximately 1.0 microg/g lipid for each compound). The PCB: DDE ratios in Cormorant lipid from some individual colonies were 2-3.5 times greater than the ratio in eggs from the same colony, suggesting an accumulation of PCBs related to local diet. Juvenile Cormorants might serve as regional indicators of chemical residue contamination in Alberta, and provide a temporal perspective on changes in contaminant burdens in aquatic ecosystems.     

Pesticides and PCBs in sediments and fish from the Salton Sea, California, USA

The Salton Sea, the largest manmade lake in California, is officially designated by the State of California as an agricultural drainage reservoir. The purpose of this study was to determine organochlorine and organophosphorous pesticides, as well as polychlorinated biphenyl (PCB) concentrations in sediments and fish tissues in the Salton Sea and evaluate the relative ecological risk of these compounds. Sediment samples were taken during 2000-2001 and fish tissues (Tilapia mossambique, Cynoscion xanthulu) were collected in May 2001. All samples were analyzed for 12 chlorinated pesticides, 6 organophosphorus pesticides, and 55 polychlorinated biphenyl (PCB) congeners. SigmaDichlorodiphenyltrichloroethane (SigmaDDT) and total PCB concentrations observed in sediments ranged from 10 to 40 and 116 to 304 ng/g dry wt, respectively. DDT/DDD ratios in sediments and fish tissues of the northern Sea in 2001 indicated recent DDT exposure. Lindane, dieldrin, dichlorodiphenylethane (DDE) and total PCB concentrations detected in sediments exceeded probable effect levels established for freshwater ecosystems, and pp-DDE and total PCB concentrations were higher than effect range-median values developed for marine and estuarine sediments. In fish liver, concentrations of endrin and SigmaDDT exceeded threshold effect level established for invertebrates. SigmaDDT concentrations detected in fish tissues were higher than threshold concentrations for the protection of wildlife consumers of aquatic biota. DDE concentrations in fish muscles tissues were above the 50 ng/g concentration threshold for the protection of predatory birds. Dimethoate, diazinon, malathion, chlorpyrifos, disulfoton varied from < or = 0.15 to 9.5 ng/g dry wt in sediments and from < or = 0.1 to 80.3 ng/g wet wt in fish tissues. Disulfoton was found in relatively high concentrations (up to 80.3 ng/g) in all organs from Tilapia and Corvina. These results demonstrate continued contamination of specific organochlorine compounds in sediments and resident fish species of the Salton Sea.     

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.