Waterbird Eggs Research Articles

Residues of Organochlorinated Pesticides in Eggs of Water Birds from Tai Lake in China

The levels of organochlorine compounds in eggs of water birds from the colony on Tai Lake in China were studied. The eggs were collected in 2000 and belonged to the following species: 65 samples of black-crowned night heron (Nycticorax nycticorax), 36 samples of little egret (Egretta garzetta), 26 samples of cattle egret (Bubulcus ibis) from 13 clutches and 43 samples of Chinese pond heron (Ardeola bacchus) from 17 clutches. Dichlorodiphenyltrichloroethane (DDT) and its derivates (DDE and DDD), hexachlorocyclohexane (HCH) and its isomers (alpha-HCH, beta-HCH, gamma-HCH, delta-HCH), heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin, endrin aldehyde, alpha-endosulfan, beta-endosulfan, and endosulfan sulfate were determined in the laboratory by gas chromatography. The data showed that DDE had the highest levels in all the samples, followed by beta-HCH. The mean levels of DDE among the water bird species were in the order as follows: black-crowned night heron (5464.26 ng/g, dry weight) > Chinese pond heron (2791.12 ng/g, dry weight) > little egret (1979.97 ng/g, dry weight) > cattle egret (660.11 ng/g, dry weight). DDT and its metabolites accounted for 90% of the total organochlorines, except that it was only 73% for cattle egret. The differences of the residue among the bird species were statistically significant and could be attributed to their variations in prey and habitat. Although the DDE burdens in Tai Lake were much lower than 8 microg/g (wet weight) which are thought to have significant adverse effects on black-crowned night herons, they would be expected to increase the risk of adverse effects on survival of chicks of herons and egrets, particularly black-crowned night heron, based on the critical value of 1 microg/g (wet weight) DDE. The burdens of HCHs in this study were higher and the cyclodienes were lower than those found elsewhere.

Persistent organochlorine pollutants in eggs of colonial waterbirds from Galveston Bay and East Texas, USA

Eggs of neotropic cormorants (Phalacrocorax brasilianus), black-crowned night herons (Nycticorax nycticorax), and great egrets (Ardea alba) nesting on several locations in Galveston Bay (TX, USA) and at two control sites outside the bay were collected during April-May 1996 and analyzed for chlorinated pesticides, PCBs, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans. Additionally, concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQs) were determined by use of relative potency factors (TEQs) or the H4IIE-luc bioassay TCDD-EQs. Concentrations of 1,1,-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) were greater in eggs of neotropic cormorants from Alexander Island (mean = 1,040 ng/g wet wt) in the Houston Ship Channel (Houston, TX, USA) and in those from Telfair Island (mean = 1,460 ng/g wet wt), a reference location outside the bay, than in most locations inside the bay (mean range = 119-453 ng/g wet wt). Mean PCB concentrations were greater in eggs of neotropic cormorants from Alexander Island (mean = 5,720 ng/g wet wt) than in eggs of cormorants from areas farther away from the ship channel, including two reference sites outside the bay (mean range = 404-3,140 ng/g wet wt). The TCDD was the main dioxin congener detected in eggs from all locations within Galveston Bay. Instrumental TEQs in eggs ranged from 67 pg/g wet weight at control sites to 452 pg/g wet weight at Alexander Island. Concentrations of TCDD-EQs determined in the H4IIE assay were correlated with instrumental TEQs and were greater in eggs of cormorants from islands within the bay, although these were farther away from the ship channel. Overall, concentrations of DDE, PCBs, TCDD, and TCDD-EQs were less than the threshold levels known to affect reproduction. However, some eggs contained concentrations of total PCBs or DDE greater than what would elicit adverse effects on birds. No identifiable deformities or abnormalities were detected in embryos collected from all sites.

Environmental Contaminants in Colonial Waterbirds from Great Slave Lake, NWT: Spatial, Temporal and Food-chain Considerations

Great Slave Lake in the Northwest Territories, Canada, differs regionally in trophic status and local and regional inputs of contaminants. Spatial and temporal trends in contaminant levels in bioindicator species such as colonial waterbirds could offer insights into the potential for contaminant bioaccumulation in Great Slave Lake. Persistent chlorinated hydrocarbon contaminants, mercury (Hg), and selenium (Se) were examined in herring gull ( Larus argentatus ) eggs and livers collected from various locations on Great Slave Lake in 1995. Eggs were collected in May and June, and livers in May and August. Also, the relationship between contaminants and trophic level, as inferred from stable-nitrogen isotope analysis (delta 15N), was examined in four colonial waterbird species: herring gull, mew gull ( L. canus ), Caspian tern (Sterna caspia ), and black tern ( Chlidonias niger ). Finally, the co-accumulation of mercury and selenium was examined in eggs of these birds. There were no differences in chlorinated hydrocarbon concentrations among four sampling sites (colonies). Concentrations did not differ between herring gull adults collected in early May and those collected in early August. Chlorinated hydrocarbon concentrations in eggs of herring gull, mew gull, Caspian tern, and black tern were related to their trophic positions as inferred from their delta 15N values in their lipid-free egg yolks. Concentrations in these colonial waterbirds were much higher than those in fish from Great Slave Lake, but lower than those in their conspecifics from the Great Lakes. It is probable that a relatively large proportion of the chlorinated hydrocarbon contaminant load in colonial waterbird eggs on Great Slave Lake results from exposure to and storage of such contaminants at more heavily contaminated wintering and staging areas. This possibility limits the usefulness of colonial waterbirds as indicators of chlorinated hydrocarbon bioaccumulation in Great Slave Lake. Selenium and mercury concentrations in herring gull eggs differed significantly among the four breeding colonies, and concentrations in adults declined between May and August. Selenium and mercury were positively correlated in eggs of all species. Key words: black tern, Caspian tern, Great Slave Lake, herring gull, mew gull, mercury, organochlorines, selenium

Contaminants in eggs of colonial waterbirds and hepatic cytochrome P450 enzyme levels in pipped tern embryos, Washington State.

Eggs of Forster's terns (Sterna forsteri) collected in 1991 from nesting colonies on Crescent Island (Columbia River) and the Potholes Reservoir in south central Washington generally contained low residues of organochlorine pesticides and metabolites, 2,3,7, 8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran, and polychlorinated biphenyls (PCBs). Hepatic cytochrome P450 enzyme activity in pipped embryos of Forster's terns from the two colonies seemed unaffected by contaminants. At Crescent Island, examination of 23 Forster's tern eggs with large embryos (19 viable [10 pipped] and four dead [two pipped]) revealed developmental abnormalities in two viable pipped embryos (missing maxilla and deformed pelvic girdle) and a viable prepipping embryo (shortened beak). Our limited sample sizes and number of compounds analyzed preclude us from determining whether or not the abnormalities are related to contaminants. No abnormalities were noted in 10 pipped eggs (nine viable and one dead at collection) of Forster's terns collected from the Potholes Reservoir colony. Eggs of Caspian terns (Sterna caspia) collected from Crescent Island in 1991 also contained generally low residues of contaminants, only one developmental abnormality was noted, and limited data indicated that cytochrome P450 enzyme activity apparently was unaffected by contaminants. Organochlorine contaminants were generally low in addled eggs of American white pelicans (Pelecanus erythrorhynchos) collected from Crescent Island in 1994.

Determination of organochlorine pesticide residues in various environments and organisms in Göksu Delta, Turkey

This study was conducted to determine organochlorine (OC) pesticide residue in various environments such as waters, sediments and soils and in organisms such as blue crabs ( Callinectes sapidus);, fish [grey mullet ( Mugil cephalus) and carp ( Cyprinus carpio)]; and waterbirds [coot ( Fulica atra), mallard ( Anas platyrynchos) and little egret ( Egretta garzetta)] during the period of October 1991–October 1993 at Göksu Delta-Tasucu, which is an internationally important wetland for the waterbirds. According to results, it was found that various environs and organisms in Göksu Delta were contaminated by 13 different OC pesticides and their residues, besides OC concentrations in soils from the agricultural areas higher than water and sediments (ranging from 0.006 ppm beta-BHC in water to 5.416 ppm pp′ DDE in agricultural soil). Residue analysis showed that OC pesticides and their residues were generally more accumulated in carp adipose tissue (o,p′ DDT 4.217 ppm mean) and waterbird adipose tissue (beta-BHC; 2.147 ppm in coots, heptachlor epoxide; 2.744 ppm in mallards). Also it was confirmed that OC pesticide residues were accumulated more in adipose tissues than in liver of fish and waterbirds. OC residues were highly encountered in eggs of waterbirds, especially in eggs of the little egret (heptachlor 0.980 ppm, pp′ DDT 1.254 ppm).

Assessing the toxic threat of selenium to fish and aquatic birds

A procedure is given for evaluating the toxic threat of selenium to fish and wildlife. Toxic threat is expressed as hazard, and is based on the potential for food-chain bioaccumulation and reproductive impairment in fish and aquatic birds, which are the most sensitive biological responses for estimating ecosystem-level impacts of selenium contamination. Five degrees of hazard are possible depending on the expected environmental concentrations of selenium, exposure of fish and aquatic birds to toxic concentrations, and resultant potential for reproductive impairment. The degree of hazard is given a numerical score: 5 = high hazard, 4 = moderate hazard, 3 = low hazard, 2 = minimal hazard, and 1 = no identifiable hazard. A separate hazard score is given to each of five ecosystem components; water, sediments, benthic macroinvertebrates, fish eggs, and aquatic bird eggs. A final hazard characterization is determined by adding individual scores and comparing the total to the following evaluation criteria: 5 = no hazard, 6-8 = minimal hazard, 9-11 = low hazard, 12-15 = moderate hazard, 16-25 = high hazard. An example is given to illustrate how the procedure is applied to selenium data from a typical contaminant monitoring program.

A Protocol for Aquatic Hazard Assessment of Selenium

A procedure is described for conducting an aquatic hazard assessment of selenium. Hazard is characterized in terms of the potential for food-chain bioaccumulation and reproductive impairment in fish and aquatic birds, which are the most sensitive biological responses for estimating ecosystem-level impacts of selenium contamination. Five degrees of hazard are possible depending on the expected environmental concentrations of selenium, exposure of fish and aquatic birds to toxic concentrations, and resultant potential for reproductive impairment. The degree of hazard is given a numerical score: 5, high hazard; 4, moderate hazard; 3, low hazard; 2, minimal hazard; and 1, no identifiable hazard. A separate hazard score is given to each of five ecosystem components: water, sediments, benthic macroinvertebrates, fish eggs, and aquatic bird eggs. A final hazard characterization is determined by adding individual scores and comparing the total to the following evaluation criteria: 5, no hazard; 6-8, minimal hazard; 9-11, low hazard; 12-15, moderate hazard; 16-25, high hazard. An example is given to illustrate how the protocol is applied to selenium data from a typical contaminant monitoring program.

Concentrations and metabolism of PCBs in eggs of waterbirds on the German North Sea coast.

Among environmental chemicals found in top predators the polychlorinated biphenyls (PCB) often occur at high concentrations and are of toxicological relevance. Not only concentrations but also the composition of the PCB mixtures, which consist of many congeners of different degrees of chlorination, vary among species and sites. In this paper we show the interspecific variation in PCB concentrations and in the degree of metabolism of the PCB mixtures in eggs of 11 waterbird species breeding on the highly polluted German Wadden Sea coast, where the PCB contamination of birds has been increasing during the last decade. 14 refs., 2 tabs.

H4IIE rat hepatoma cell bioassay-derived 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in colonial fish-eating waterbird eggs from the Great Lakes.

Fish-eating waterbirds from the Great Lakes of North America have shown symptoms of poisoning similar to those observed in laboratory exposures of various avian species to planar halogenated hydrocarbons (PHHs). PHHs, include among others, polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs), and have been implicated in some of the reproductive problems of Great Lakes water-birds. The objectives of this study were to assess the overall potencies of PCB-containing extracts from colonial water-bird eggs taken from the Great Lakes and to compare the potencies with the location and spatial distribution of the colonies. The potencies of the extracts were assessed by their ability to induce cytochrome P450IA1-associated ethoxyresorufin O-deethylase (EROD) activity in H4IIE rat hepatoma cells as compared to the standard, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The H4IIE bioassay-derived TCDD-equivalents (TCCD-EQs) in the waterbird eggs concur with residue analyses and biological data from other studies. The greatest concentrations of TCDD-EQs were found in waterbird eggs from historically polluted, industrialized or urbanized areas in which the reproductive impairment of colonial waterbirds was most severe. However, significant concentrations of TCDD-EQs were detected at all sites tested; with a range of 49 to 415 pg TCDD-EQ/g egg, uncorrected for extraction efficiencies. The H4IIE bioassay proved to be a useful biomonitoring tool to assess the overall potency of complex PHH mixtures in environmental samples.

Planar chlorinated hydrocarbons (PCHs) in colonial fish-eating waterbird eggs from the Great Lakes

Reproductive impairment of double-crested cormorants ( Phalacrocorax auritis) and Caspian terns Hydroprogne caspia) has recently been observed in the Great Lakes of North America. Planarchlorinated hydrocarbons (PCHs), which include polychlorinated biphenyls (PCBs), polychlorinated dibenzo- p-dioxins (PCDDS), and polychlorinated dibenzofurans (PCDFs), are believed to be at least partially responsible for the increased incidence of teratogenesis and embryonic mortality. The objective of this study was to assess the potency of the PCH mixtures in egg extracts from these colonial waterbirds. The relative potency of the egg extracts was assessed by their ability to induce cytochrome P-450-dependent ethoxyresorufin O-deethylase (EROD) in H4IIE rat hepatoma cells. The magnitude of the response was compared with EROD induction in cell cultures by a standard, 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD). The TCDD-equivalents derived by this bioassay concur with residue analysis and biological data, in that the highest TCDD-equivalents were found in waterbird egg composites from areas with greater PCH concentrations and more severe reproductive effects. Significant concentrations of PCHs were detected in all sites tested; the range of TCDD-equivalents in the waterbird eggs was 49–415 pg/g, uncorrected for extraction efficiencies. The evidence is strong for at least a partial role of PCHs as causal agents in the reproductive impairment of fish-eating waterbirds from the Great Lakes of North America.

Variations in polychlorinated biphenyl congener composition in eggs of Mediterranean water birds in relation to their position in the food chain

The concentrations of the principal PCB congeners and the ΣPCB were determined in eggs of eight species of water birds collected in two areas of the Mediterranean region. The results for ΣPCB levels indicate statistically significant differences between the species; in the Po delta the higher values are for those species which feed mainly on fish. Differences exist between the congeners and their percentages when compared with the total residue. Tetrachlorobiphenyls constitute a larger proportion of the ΣPCB in Avocet and Black-winged Stilt, two species whose diet consists mainly of invertebrates. The main component in all the species is 22′44′55′ and its presence varies between 11·4% in Avocet and 21·2% in Audouin's Gull. It is suggested that there is a link between the uptake of PCBs and the position of the species in the food chain.