EFFECTS OF PCDDS, PCDFS AND PCBS IN COMMON TERN (STERNA-HIRUNDO) BREEDING IN ESTUARINE AND COASTAL COLONIES IN THE NETHERLANDS AND BELGIUM

In 1991, eggs of the common tern (Sterna hirundo) were collected at ei ght different locations and incubated artificially. The residual yolk sacs of the hatchlings from the highly polluted colonies, located in t he main sedimentation area of the Rhine and Meuse rivers, contained on average 16 ng TEQ (toxicity equivalency) per gram lipid, which was fi vefold higher than the concentrations in the reference colony. The hep atic EROD activity was induced fourfold compared to the reference colo ny (p < 0.005). At the individual level, a significant relationship wa s found between log TEQ and both log EROD and log PROD (r = 0.568, p < 0.05 and r = 0.661, p < 0.02, respectively). Average TEQ concentratio n in chicks that hatched after 23 d of incubation were twice the conce ntration of those that hatched after 21 d (p < 0.05). No concentration -related effects on morphology and physiology were found. The non-orth o- and mono-ortho-PCBs were predominant regarding the total TEQ, while the PCDDs and PCDFs contributed less than 10%. The PCB patterns were highly similar among the individual birds and among different location s. In contrast, PCDD and PCDF patterns were not similar at all locatio ns, and two distinct patterns could be recognized and related to sedim ents that were deposited during different time periods.