Green kingfishers as sentinel species for mercury contamination in Amazon

Abstract

Mercury is a global contaminant naturally found in the Amazon; it can be biomagnified in the aquatic trophic chain. The use of piscivorous avians for mercurial contamination biomonitoring is increasing, mainly due to the non-mobility of mercury in avian feathers. We examined the concentrations of total mercury and methylmercury in different Chloroceryle americana tissues from the Teles Pires and Juruena Rivers in the southern Brazilian Amazon. We also evaluated total mercury in small Characidae fish (potential C. americana food) in the same areas. The results evidenced high mercury concentrations, on average two-times higher in the green kingfishers from the Teles Pires River compared to the Juruena River; the same results were found for the fish specimens. Mercury concentrations were lowest in the muscle, followed by liver and highest in feathers. Fifty-eight per cent of the feather samples from the Juruena River and 90% from the Teles Pires River had total mercury concentrations above 5 µg/g, a level previously associated with adverse effects related to avian breeding. The methylmercury concentration was lowest in the liver, followed by feathers and highest in muscle. Although Juruena River avian feathers had a lower total mercury concentration, > 96% of the total mercury was methylmercury, the highest amount for specimens from both rivers.