Organochlorines and mercury in livers of great cormorants (Phalacrocorax carbo sinensis) wintering in northeastern Mediterranean wetlands in relation to area, bird age, and gender.

Wild birds are exposed to pollutants in their habitats. Top consumers of aquatic environments such as the fish-eating great cormorant (Phalacrocorax carbo sinensis) are especially affected due to the bioaccumulation of toxic substances in their tissues. This study analysed the livers of 80 great cormorants from Greece to estimate the concentration of organochlorines and mercury and to examine their possible toxic effects and origin. The results showed that mercury (geometric mean 8089 ng g⁻¹ dw), p,p'-DDE (2628 ng g⁻¹ dw), ∑HCHs (47 ng g⁻¹ dw) and HCB (116 ng g⁻¹ dw) concentrations can be considered high compared with those found in great cormorant livers elsewhere except in highly polluted areas, whereas ∑PCBs occurred in relatively low concentrations (1091 ng g⁻¹ dw). ß-HCH was the dominant HCH isomer. Pollutant levels were generally unrelated to area, age and gender. However, p,p'-DDE and p,p'-DDD showed intersite differences, whilst the proportion of PCBs with 8 chlorine atoms were significantly higher in adult than 1st year great cormorants. Pollution did not reflect local patterns but rather these along the Baltic and Black Seas, whilst differences in p,p'-DDE concentration and ∑DDTs/∑PCBs ratios between Evros, Axios or Amvrakikos, found on common migration route, suggested different bird origins. Most birds had toxic mercury concentrations; 83.7% above 4000 ng g⁻¹ dw and 16% above 17,000 ng g⁻¹ dw. Other pollutant levels were too low to have adverse effects.

PCB levels and accumulation patterns in waterbird eggs and in their prey at Lake Kerkini, a north-eastern Mediterranean wetland of international importance.

Seven "target" PCB levels were determined and compared in waterbird eggs, in their prey, and in water at Lake Kerkini, northern Greece, to investigate PCB bioaccumulation patterns and to define the best bioindicator of target PCBs for this area. PCBs were analysed from eggs of Phalacrocorax carbo, Podiceps cristatus, Ardea cinerea, Egretta garzetta, and Nycticorax nycticorax and from prey types Alburnus alburnus, Rutilus rutilus, Lepomis gibbosus. Carassius auratus, and Rana sp. PCBs analysed were detected in all bird eggs, prey, and water but contamination patterns differed among these sample types. The lipid-corrected geometric means of the congeners analysed were significantly different among most bird species and among some prey species. PCB congeners 118, 138, 153, and 180 accounted for around 80% of the total PCB contamination in bird egg samples. Percent congener concentrations of high-chlorinated PCBs tended to increase from water through prey to most bird egg samples whereas the low chlorinated PCBs (28 and 52) decreased. Bioaccumulation factors (BAFs) also exhibited an increasing trend for higher chlorinated PCBs from prey types to bird eggs. The greatest BAFs of six of the congeners were shared between Phalacrocorax carbo and Ardea cinerea. Among prey, the BAFs of four PCBs were highest in Lepomis gibbosus. Biomagnification factors varied between 1.01 and 39.57. In contrast to low chlorinated PCBs, high chlorinated congeners biomagnified considerably through fish prey. The highest biomagnification took place in Phalacrocorax carbo. No relationship was found between the lipid content of samples and BAFs of PCBs probably due to biotransformation differences of the congeners in the biota sampled. Due to the greatest PCB concentrations especially of the higher chlorinated PCBs in the eggs of Phalacrocorax carbo and its considerable bioaccumulation tendencies, it is proposed as the best PCB biomonitor of target PCBs at Lake Kerkini. Lepomis gibbosus had the highest concentrations of most congeners and exhibited the greatest bioaccumulative properties among prey and can be used as an alternative biomonitor.

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.

PCBs and organochlorine pesticide residues in eggs of Audouin's gull (Larus audouinii) in the north-eastern Mediterranean.

Levels of eight PCB congeners (IUPAC 8, 20, 28, 52, 101, 118, 138, 180) and 13 organochlorine pesticides (alpha-BHC, beta-BHC, lindane (gamma-BHC), heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, 2,4'-DDT, 2,4'-DDD, 4,4'-DDT, 4,4'-DDD, 4,4'-DDE) were measured in unhatched Audouin gull eggs from Aegean Sea (northeastern Mediterranean) colonies in 1997 and 1998. Levels of more persistent congeners 138, 180 and in some colonies 118, predominated among PCBs. Between years significant differences were found in the levels of a variety of contaminants in the same regional colonies (Lipsos, Agathonisi, and Fourni) attributable to temporal changes in diet. Within years differences were limited (1997: PCB congeners 52, 118, 180, heptachlor and 4,4'-DDD; 1998: PCB congener 8 and heptachlor epoxide) which in combination with cluster analysis suggest a temporal rather than spatial pattern of pollution in the Aegean Sea. Maximum median levels of five PCB congeners, total PCBs and eight organochlorine pesticides were found in the Agathonisi and Fourni colonies suggesting an elevated nearby pollution probably from the polluted Menderez River. Levels of all contaminants were too low to have any adverse reproductive effects on the Audouin's gull of the Aegean colonies.

Lead and cadmium in eggs of colonially nesting waterbirds of different position in the food chain of Greek wetlands of international importance.

Lead and cadmium concentrations were measured in eggs of collonially nesting waterbirds with different position in the food chains of Greek wetlands of international importance. Differences were found between species in the levels of both lead and cadmium in the Evros and Axios Deltas attributable to their different diets. Nevertheless, the concentration in eggs was unrelated to the position of each species studied in its food chain. There was no significant difference in lead levels among four wetlands sampled for the cormorant and in Cd levels among three wetlands sampled for the Mediterranean gull, probably implying species-specific accumulation patterns. A higher lead pollution of the Axios Delta area was only reflected in the eggs of the Mediterranean gull. The very low concentrations of both metals found in the eggs may either suggest low environmental inputs or lack of sensitivity in using eggs as lead and cadmium biomonitors, thus a more sensitive bioindicator still remains to be found.

Mercury in feathers of Squacco Heron (Ardeola ralloides) chicks in relation to age, hatching order, growth, and sampling dates.

We studied the relationships between mercury content of Squacco Heron (Ardeola ralloides) chick body-feathers and nestling age, hatching order (seniors-juniors) and growth parameters, and the date of feather sampling in the Axios Delta, northern Greece, in 1993 (n = 75 chicks) and 1994 (n = 80). Mercury levels were not significantly correlated with chick age in either year of the study. Most of the variability in mercury (90%) was found among broods, attributable to differential prey selection and/or foraging habitat and patch utilization by parents. Within broods, juniors had significantly higher mercury loads than seniors in 1993, but there was no significant difference between the two in 1994. Correlations of nestling weight and linear measurements corrected for chick age and mercury concentrations were never significant and explained small amounts of variability in chick growth. However, linear measurements corrected for age were significantly higher among seniors in 1993, when those nestlings had lower mercury loads than their siblings. Mercury levels were unaffected by the date of feather collection in 1993, but exhibited a significant increase over time in 1994. This can be attributed to a shift towards more highly contaminated habitats and prey types by foraging parents, resulting from seasonal changes in water level and vegetation cover in important foraging habitats. Feather collection from Squacco Heron nestlings late in the breeding season seems to be an appropriate method for biomonitoring mercury pollution in the Axios Delta.

The incidence of polychlorinated biphenyl and organochlorine pesticide residues in the eggs of the cormorant (Phalacrocorax carbo sinensis): an evaluation of the situation in four Greek wetlands of international importance.

This study contributed to identifying the current levels of organochlorine pollutants in four Greek wetlands of international importance (the Evros and Axios Deltas, and Kerkini and Prespa Lakes), using the cormorant Phalacrocorax carbo sinensis as a suitable bioindicator in a region where such information is scarce. Residue levels of eight polychlorinated biphenyl (PCB) congeners and 13 organochlorine pesticide (OC) compounds were measured in cormorant eggs. Most PCBs and OCs (except dieldrin and endrin) were found in at least some of the study areas. Median concentrations of five PCBs (IUPAC 8, 20, 52, 138, 180) and of six OCs (alpha-BHC, beta-BHC, lindane, heptachlor, 4,4'-DDE and 4,4'-DDT) differed significantly among the areas. The median totals of the PCBs were highly significant among the areas, being unexpectedly highest in Prespa Lake (68.43 ppb), despite its remoteness, and lowest in Evros Delta samples (12.17 ppb). Aldrin that was found in samples from Evros, Axios and Prespa probably accumulated in wintering grounds. In all of the areas, the relative proportions of alpha-BHC and 2,4'-DDD were the highest of all OCs. Fingerprint and cluster analyses illustrated overall differences in the PCB patterns, being greatest between the deltas than between the lakes, but, inversely, for OCs the differences were smaller in the deltas. Differences were attributed to large variations in the cormorants' diet between areas and different regimes of pollutant management in the two types of wetland. Correlations of pollutants varied considerably among areas and they were more diverse in OCs. The sum of OCs/ sum of PCBs ratio indicates agrochemical pollution in all areas. An important finding was that levels of both pollutant groups were too low to have any biological implications on the cormorants and, additionally, suggest that they have a negligible impact on the environment of the wetlands studied.

Mercury in feathers of Audouin's gull (Larus audouinii) chicks from northeastern Mediterranean colonies.

Feathers of Audouin's gull chicks from three Aegean island areas (north Dodecanese, Cyclades, Kythera) Greece, were sampled in 1997 and 1998 and analyzed for mercury. Mean concentrations varied from 0. 94 microg/g (Lipsos, Dodecanese, 1998) to 2.14 microg/g (Paros, Cyclades, 1998). Significant differences between years occurred in some regions (Lipsos, Fourni) but not in others (Paros). Within each year, especially in 1998, mean mercury concentrations differed among colonies. Results did not support the prediction that mercury levels would be higher in the north Dodecanese area due to the proximity of the polluted Menderes delta. There was no relationship between estimated chick age and feather mercury contents (r = -0.04, NS). Detected mercury levels do not seem to pose any toxic hazard to the Aegean Audouin's gull populations. However, the ease of sampling from gulls indicates that they may be a useful biomonitor of mercury contamination in this region.

Mercury in feathers of little egret Egretta garzetta and night heron Nycticorax nycticorax chicks and in theirprey in the Axios Delta, Greece.

Mercury concentrations were measured in feathers oflittle egret and night heron chicks and in their prey in the Axios Delta,Greece. Significantly higher concentrations occurred in night heron than inlittle egret in 1993. In the night heron the mercury content of feathers wasnegatively correlated to the size of chicks, possibly due to inhibition ofgrowth. Mercury concentrations were higher than reported for heron feathersin seriously polluted sites in North America and Japan, but the toxic hazardis unclear. Diets differed considerably between the two species due to use ofdifferent foraging habitats and this seems responsible for different mercurycontents of feathers. Mercury concentrations in the pumpkinseed sunfishLepomis gibbosus, goldfish Carrassius auratus, and indragonfly Odonata larvae were the highest among the prey categories. Frogs and water beetles Dytiscidae had moderate concentrationswhereas saltwater fish and terrestrial prey had very low mercuryconcentrations. The implication is that the deltaic marshes are the habitatmost polluted with mercury. Night heron chick feathers, freshwater fish anddragonfly larvae could be used to monitor mercury contamination in thisregion, but use of bird feathers alone could give misleading results ifchanges in diet occurred.

Concentration and bioaccumulation of organochlorine pesticide residues in herons and their prey in wetlands of Thermaikos Gulf, Macedonia, Greece.

Concentrations of the principal organochlorine insecticides were determined in eggs and freshly dead chicks of the Squacco heron (Ardeola ralloides), Little Egret (Egretta garzetta) and Night Heron (Nycticorax nycticorax), as well as in frogs (Rana sp.), the main heron prey. Material was collected from the wetlands of the Thermaikos Gulf (Macedonia, northern Greece) in 1992 and 1993. Residues of the organochlorine pesticides alpha-BHC, beta-BHC, lindane, 4,4'-DDD, 4,4'-DDE, heptachlor and dieldrin were found in the eggs, chicks and prey of the herons. alpha-BHC, beta-BHC, and lindane had highest concentration in the Night Heron and lowest in the Little Egret. In all samples examined, the bioconcentration factors (BCF) of these compounds had very high values. BCF of pollutants for the eggs of the Squacco Heron were at lower levels than those of its chicks. BCF for frogs were in almost all cases lower than those for the other samples. Biomagnification factor (BMF) for 4,4'-DDE and beta-BHC had the highest values of all other compounds (except in the Night Heron). BMF for the eggs of the Squacco Heron were greater than for its chicks. Variation in the pesticide contents in the different heron species is attributed to different feeding habits; the exception being the occurrence of dieldrin in eggs only and 4,4'-DDE as a remnant of past spraying. Amounts of pesticides detected in this study are too low to affect eggshell thickness in the Squacco Heron or have other effects on the wildlife of the area.