Ga. Fox et al., MONITORING THE ELIMINATION OF PERSISTENT TOXIC-SUBSTANCES FROM THE GREAT-LAKES - CHEMICAL AND PHYSIOLOGICAL EVIDENCE FROM ADULT HERRING-GULLS, Environmental monitoring and assessment, 53(1), 1998, pp. 147-168
To assess progress towards virtual elimination of PCBs, DDE, dieldrin
and Mirex and their associated physiological effects, we compared thei
r concentrations in pooled livers of adult herring gulls (Larus argent
atus) repeatedly sampled at 8 Great Lakes colonies and a reference col
ony on the Atlantic coast between 1974 and 1993. We measured the relat
ive thyroid mass and concentrations of highly carboxylated porphyrins
and retinyl palmitate in the liver of each individual. PCBs, dieldrin
and mirex declined in 7 of 8 colonies while DDE decreased in six. The
greatest decreases occurred pre-1985. PCBs and DDE did not decrease in
gulls from Middle Island in western L. Erie. Middle Island and Sagina
w Bay had the highest concentrations of PCBs of 11 Great Lakes colonie
s in the 1990s. Thyroids of gulls from Great Lakes colonies were sligh
tly enlarged but the degree of enlargement has decreased over time. In
1991, gulls from Great Lakes colonies had slight to moderately elevat
ed concentrations of highly carboxylated porphyrins. In the early 1990
s, hepatic stores of retinyl palmitate were very seriously depleted in
gulls from the Detroit River, western basin of Lake Erie, and Lake On
tario, reflecting decreased availability and altered storage. We concl
ude that PCBs and/or other persistent toxic substances in the food of
herring gulls have not been virtually eliminated.