Green Kingfishers as Sentinel Species for Mercury Contamination in Amazon

Abstract

Mercury is a global contaminant found in the Amazon; it can be biomagnified in the aquatic trophic chain. The use of piscivorous birds for biomonitoring of mercury contamination is increasing, mainly due to the non-mobility of mercury in bird feathers. We examined the concentrations of total mercury and methylmercury in different tissues of the green kingfisher, Chloroceryle americana collected 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 indicate contamination of the birds with high 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. 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 bird breeding. The methylmercury concentration was lowest in the liver, followed by feathers and highest in muscle. Although Juruena River bird feathers had a lower total mercury concentration, > 96% of the total mercury was methylmercury, the highest amount for specimens from both rivers. Although the concentration of Hg in the muscle of the green kingfisher is higher when compared to the feather and liver, the non-invasive monitoring through analysis of samples of feathers is an efficient biomonitoring tool for evaluation of mercury contamination in tropical birds.