BIOMONITORIUM OF HEAVY METALS IN AQUATIC BIRDS OF RESIDENTS OF THE LAKE OF CHAPALA, MEXICO

Lake Chapala is considered important because of the economic, recreational, and ecological services that it offers. The main water source of the lake is the Lerma river, which receives industrial waste discharges from the states of Mexico, Queretaro, and Guanajuato, as well as municipal and agricultural waste discharges from the states of Michoacan and Jalisco. Contaminants present in such waste discharges can accumulate through the food web and affect other species in the Chapala ecosystem. We estimated heavy metal pollution in the lake by measuring concentrations of Ag, As, Cd, Cr, Hg, Pb, Sr and Ti in water and sediments, and in feathers from three resident aquatic birds (Ardea alba, Egretta thula, Nycticorax nycticorax). The analysis of heavy metals in feathers was performed using inductively-coupled mass spectrometry. A. alba had significantly greater concentrations of Pb (43.65 mu g/g) and Cr (52.47 mu g/g) in feathers (rachis) than E. thula and N. nycticorax (p <= 0.05). The biota-sediment bioacccumulation factors suggest accumulation of Ag, As, Cd, Cr, Cu, Hg and Pb in birds from Lake Chapala. Feathers from resident aquatic bird species in Lake Chapala can be used as a non-lethal procedure useful for monitoring heavy metal contamination.