Mercury distribution in blood, tissues, and feathers of double-crested cormorant nestlings from arid-lands reservoirs in south central New Mexico

Eggs, blood, liver, muscle, and feathers were analyzed for concentrations o f total mercury in double-crested cormorant (Phalacrocorax auritus) nestlin gs from two reservoirs in south central New Mexico. Total mercury concentra tions among eggs, tissues, and feathers were not significantly correlated. Concentrations of total mercury averaged 0.40 mu g/g in liver and 0.18 mu g /g in muscle tissues in both populations of nestlings. There were no signif icant changes in concentrations of total mercury in whole blood of nestling s collected 7-10 days and 17-22 days posthatch in Caballo Reservoir (0.36 m u g/g and 0.39 mu g/g, respectively) and in Elephant Butte Reservoir (0.36 mu g/g and 0.34 mu g/g, respectively). Total mercury concentrations were si milar for blood, muscle, and liver in nestlings for both reservoirs. Total mercury concentrations were higher in eggs and tail, primary, and secondary feathers from nestlings at Caballo Reservoir compared to Elephant Butte Re servoir Although there were no differences in concentrations of total mercu ry in fishes between the two reservoirs, bioaccumulation and biomagnificati on was evident in planktivorous and piscivorous fishes. The data demonstrat e that feather analysis may not be a good predictor of tissue burden in nes tlings from regions of low contamination.