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  • 1
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Unhatched eggs and plasma samples from prefledged bald eagles (Haliaeetus leucocephalus) from a recovering population in the Canadian Great Lakes Basin were contaminated with organochlorine compounds at levels comparable to those reported for eagle populations in several areas of the United States. PCBs were among the most commonly detected contaminants and occurred at high concentrations in plasma. Plasma PCB concentrations in Lake Erie nestlings were significantly higher than in chicks from Lake Nipigon (0.130 and 0.047 mg/kg wet weight, respectively). Blood levels of mirex were higher in nestlings from Lake Superior compared to those from Lake Erie (0.0012 and 0.0006 mg/kg wet weight, respectively). Migration routes and over-winter locations of avian prey that constitute a part of the bald eagle chick's diet are likely to contribute to these spatial contaminant patterns in plasma. Atmospheric deposition and a cold condensation effect for chlordane compounds may have produced higher levels of these compounds in plasma samples from Lake Superior compared to samples from Lake Erie (0.020 and 0.008 mg/kg wet weight, respectively). Levels of DDE in plasma were generally low, ranging in concentration from 0.02 mg/kg wet weight for lakes Erie and Nipigon to 0.06 mg/kg wet weight for Lake Huron. Concentrations of organochlorines in eaglet plasma remained relatively stable between 1990 and 1996; no significant trends associated with year of sampling were detected. The data from Lake Erie showed no correlation between productivity and plasma levels of PCBs or DDE during this time period. There were no indications that the concentrations of contaminants detected were adversely affecting productivity in Canadian Great Lakes bald eagle populations. Residue levels in eggs from Lake Erie eagle territories were equally or more contaminated than eggs from other highly contaminated environments in the United States such as the Great Lakes and Columbia River estuary. Concentrations of DDE and PCBs in Lake Erie eggs declined significantly between 1974 and 1994. Although dieldrin and chlordane levels showed a similar decline, these relationships were not statistically significant. Mirex concentrations were relatively stable. Eggs from Lake of the Woods were significantly less contaminated than those from Lake Erie (PCBs: 3 and 84 mg/kg wet weight, respectively; DDE: 3 and 24 mg/kg wet weight, respectively). Reproductive success (number of young produced/active nest) remained constant between 1982 and 1996 and productivity is sufficient to maintain an increasing population. The number of active nests has increased during this period indicating that the population is expanding and might be expected to do so until suitable habitat becomes limiting. Reductions in organochlorine levels, reintroduction efforts, immigration from other populations, and changes in habitat quality have likely contributed to the observed growth in the number of breeding pairs.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. Experiments were conducted to compare the sensitivity of primary cultures of common tern (Sterna hirundo) and chicken (Gallus domesticus) embryo hepatocytes to cytochrome P4501A (CYP1A) induction and porphyrin accumulation after exposure to halogenated aromatic hydrocarbons (HAHs) or tern egg extracts. The HAHs tested were 2,3,7,8-tetrachlorodibenzo-p -dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF) 3,3′,4,4′-tetrachlorobiphenyl (PCB 77; IUPAC nomenclature), 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126), 3,3′,4,4′,5,5′-hexachlorobiphenyl (PCB 169) and Aroclor® 1254 (a commercial mixture of PCBs). Extracts were prepared from common tern eggs collected from three sites in the Great Lakes basin and one reference site on the east coast of Canada. CYP1A induction was assayed as ethoxyresorufin-O-deethylase (EROD) activity and/or immunodetectable CYP1A protein, and total intracellular porphyrin accumulation was measured fluorometrically. Unlike chicken embryo hepatocyte (CEH) cultures, no intracellular porphyrin accumulation was observed after treatment of tern embryo hepatocyte (TEH) cultures with HAHs or egg extracts. TEH cultures were ∼50 to 〉1600 times less sensitive than CEH cultures to HAH-mediated CYP1A induction. In contrast, TEH cultures were either approximately equally sensitive or only 3.5–15 times less sensitive than CEH cultures to CYP1A induction mediated by tern egg extracts. These data suggest that common tern embryos may be more susceptible to the CYP1A inducing effects mediated by complex mixtures of environmental contaminants than indicated by their response to individual HAHs.
    Type of Medium: Electronic Resource
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