Ardea
Official journal of the Netherlands Ornithologists' Union

login


[close window] [previous abstract] [next abstract]

Van Den Berg M., Craane L.J., Van Mourik S. & Brouwer A. (1995) The (possible) impact of chlorinated dioxins (PCDDS), dibenzofurans (PCDFS) and biphenyls (PCBS) on the reproduction of the Cormorant Phalacrocorax carbo: An ecotoxicological approach. ARDEA 83 (1): 299-313
In this study the possible adverse health effects of chlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were studied in the Cormorant after in ovo exposure. A total of 38 eggs were collected from colonies in the Dordtse Biesbosch and Oude Venen area (The Netherlands), 16 of which were hatched in an incubator. At regular intervals during the incubation period O2 consumption and CO2 production were monitored. At day 1 of birth several morphological parameters (body, liver and yolksac mass, head size, tarsus length and egg shell mass) were measured. The yolksac was used for PCB, PCDD and PCDF analysis. Blood plasma and liver were collected for biochemical analyses to determine cytochrome P4501A1 or 2B1/2 activity, vitamin A and thyroid hormone levels. On the average higher levels of PCBs (2 to 5 times) and PCDD/Fs (25%) were found in the yolksac of hatchlings from the Dordtse Biesbosch colony as compared to the Oude Venen colony. These differences in residue levels concurred by an increased in ovo O2 consumption and CO2 production of the embryos, induction of cytochrome P4501A1 (by 30%), reduced plasma thyroid hormone levels (by 50%) and hepatic vitamin A levels (by 50%) in birds from the Dordtse Biesbosch colony. Significant concentration-effect relationships with PCBs and/or PCDD and PCDFs were observed for cytochrome P45O1A1, free thyroxine, weight of the yolksac, relative liver weight and head size. Based on the results of this study, it can be concluded that in ovo levels of these compounds are above the no observed effect level for the Cormorant. This in ovo exposure may play some role in the reduced reproductive success of the Cormorant in the Dordtse Biesbosch area. However, post-natal exposure and parental behaviour cannot be excluded as other contributing factors to the low breeding success observed in the field.


[close window] [previous abstract] [next abstract]