Ecology and contaminant exposure of Lake Calumet Black-crowned Night Herons: Population Levels and Nesting Ecology Final Report

We examined a suite of organic and inorganic analytes in a sample of Black-crowned NightHeron (BCNH) embryos collected from a colony located adjacent to Lake Calumet in southeastern Chicago, Illinois, in 2002. Our objectives were to determine whether embryos from the Lake Calumet colony had greater exposure to environmental contaminants, when compared to samples from other contemporary populations, and if such exposure was great enough to produce changes in selected endpoints. BCNH embryos from the Lake Calumet colony had greater exposure to PCBs, DDE and other organochlorine pesticides, cobalt, and selenium than those from colonies in northwestern MN and coastal VA. Contaminant levels in IL embryos were consistent with those reported for some colonies located in industrialized urban areas, though were not among the highest reported. Activities of Cytochrome P450 monooxygenase proteins EROD and BROD were greatly increased in IL embryos, compared to reference colonies. I,PCB concentrations were associated with EROD/BROD induction. [:PCBs, DDE, transnonachlor, Co, and Se in combination were associated with variation in cellular DNA content; DDE contributed most to this relationship. Measures of oxidative stress did not differ among colonies, however, GSSG activity was elevated and associated with concentrations of the suite of elements examined in this study. Concentrations of BZ#77, the most toxic of the PCB congeners we examined, in some IL specimens exceeded lower observed effectsleyels established tdrchickens. The concentrations of Se in eggs of BCNH from IL approached published effects thtesholds. BCNH are relatively resistant to the effects of contaminant exposure.; although there was increased exposure in this colony we did not observed any dramatic effects on the health of the embryos. Contaminants at these levels in eggs may be of concern in piscivorous waterbird species that are more sensitive to contaminant exposure than BCNH.