Ka. Grasman et al., REPRODUCTIVE AND PHYSIOLOGICAL-EFFECTS OF ENVIRONMENTAL CONTAMINANTS IN FISH-EATING BIRDS OF THE GREAT-LAKES - A REVIEW OF HISTORICAL TRENDS, Environmental monitoring and assessment, 53(1), 1998, pp. 117-145
During the 1950s and 1950s, reproductive failures and population decli
nes were observed in fish-eating birds such as gulls, terns, cormorant
s, herons, and eagles in the Great Lakes. DDE-induced eggshell thinnin
g contributed to these declines, but other factors such as embryo toxi
city also were implicated. With reduced releases of many pollutants, r
eproduction recovered in some species. However, biomonitoring during t
he 1980s and 1990s indicates continuing effects at highly contaminated
sites. Improved analytical techniques and bioassays have allowed the
assessment of the total dioxin-like toxicity of complex mixtures of or
ganochlorines (TCDD-equivalents). Developmental defects such as embryo
mortality, deformities, and edema have been associated with dioxin-li
ke PCBs in several avian species. Improved biochemical techniques have
allowed the measurement of biomarkers that detect physiological alter
ations associated with contaminants. Specific biomarkers studied in Gr
eat Lakes birds include cytochrome P-450 monooxygenases, highly carbox
ylated porphyrins, thyroxine, vitamin A, and immune function. Reproduc
tive and physiological alterations are associated with population-leve
l effects in Caspian terns and bald eagles that feed on highly contami
nated fish. Biomonitoring using biomarkers and population-level measur
es in fish-eating birds will continue to be important for assessing th
e effects of contaminants on the Great Lakes ecosystem.