Consequences for ducks of a chronic exposure to petroleum residues in their breeding marshes: The case of the Czantoria

On May 8, 1988, the tanker Czantoria collided with the dock at Levis, Quebec, spilling about 400 tonnes of light oil into the St. Lawrence River. The spill affected a number of important wildlife habitats. Following the spill and the subsequent river cleanup, domestic ducks were placed for a two-month period in marshes previously contaminated with oil. Wild ducklings were also collected in the area. Despite the small sample (a number of domestic ducks disappeared during the field experiment), it is believed that the cleanup effort was a success. The domestic ducks and wild ducklings collected on affected coastal marshes showed few of the symptoms characteristic of oil contamination. With respect to physiological effects, ducks raised in the previously contaminated area nonetheless encountered famine, as indicated by their steady weight loss and the drop in plasma proteins and blood cell counts accompanied by active rejuvenation of red blood cells. These symptoms can probably be attributed to a lack of food suitable at least for this species in the intertidal marshes of the sites under study. With respect to organochlorine contamination, polychlorinated biphenyls do not pose a problem and the few contaminants detected in trace concentrations, although found at slightly higher levels in the affected area, cannot be directly associated with the oil spill. 10 refs., 1 fig., 11 tabs