BIOCHEMICAL AND TOXIC EFFECTS OF POLYCHLORINATED BIPHENYLS (PCBs), DIBENZO-p-DIOXINS (PCDDs) AND DIBENZOFURANS (PCDFs) IN THE CORMORANT (PHALACROCORAX CARBO) AFTER IN OVO EXPOSURE

Abstract

Ecological investigations revealed differences in breeding success of cormorants (Phalacrocorax carbo) between two colonies in The Netherlands In this study the possible role of organohalogen pollutants was investigated. Thirty‐nine cormorant eggs were collected from two colonies with marked differences in contamination Seventeen cormorant eggs were hatched in an incubator. The respiration rate was monitored regularly during the incubation. Hatchlings were euthanized at day 1 Several morphological parameters were measured PCBs and polychlorinated dibenzo‐p‐dioxins (PCDDs) and dibenzofurans (PCDFs) were analyzed in the yolk sac Blood and liver were collected for analysis of cytochrome P450, ethoxyresorufin‐O‐deethylation (EROD) and pentoxyresorufin‐O‐depentylation (PROD) activities, vitamin A, and thyroid hormone levels. Residue levels differed two‐ to five‐fold for PCBs and 25% for PCDDs and PCDFs between both colonies Birds from the most contaminated colony showed an increased in ovo respiration rate, increased cytochrome P450 and EROD activity, and reduced plasma thyroid hormone and hepatic retinyl palmitate levels. Large interindividual differences were observed for all parameters The data were compared on an individual basis (n = 17) to detect any concentration‐effect relationships. Significant (p < 0 05) concentration‐effect relationships were observed for EROD induction, plasma free thyroxine reduction, yolk sac weight, relative liver weight, and head size. It is concluded these compounds may, at least in part, have played a role in the observed low breeding success of cormorants

Characterization of Potential Endocrine-Related Health Effects at Low-Dose Levels of Exposure to PCBs

“…Significant dose-dependent reductions in plasma thyroid hormone concentrations TT4 and FT4 were observed in cormorant hatchlings from high PCBcontaminated breeding colonies compared to those from low PCB-contaminated colonies (61). The number of hatchlings and fledglings in the high-contaminated breeding colony was significantly reduced compared to that in the low-polluted colony.…”

Contaminant-Related Suppression of Delayed-Type Hypersensitivity and Antibody Responses in Harbor Seals Fed Herring from the Baltic Sea

“…However, the concurrent and similar results in the DTH and the antibody responses in the Baltic Sea group as Efforts to detect possible immunosuppression in free-ranging populations of marine mammals is fraught with difficulties due to the complexity of the mammalian immune system and the difficulty in obtaining reliable samples. However, field studies have demonstrated that it is possible to obtain useful immunological information from free-ranging seals (42,43), and correlative approaches similar to those used in wildlife toxicology (44) may provide the best direction for research in the future. …”

A Review of Chemically-Induced Alterations in Thyroid and Vitamin a Status From Field Studies of Wildlife and Fish

“…This study examined cormorant (Phalacrocorax carbo) hatchlings from two colonies with different levels of exposure to PCBs, PCDDs and PCDFs (van den Berg et al, 1994). A 50% difference in reproductive success was observed between the two colonies in the field, and the more contaminated colony had two to five times the level of PCBs and 25% more PCDD and PCDFs in yolk sacs.…”