Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon

Abstract

Since 1979 the gold rush in the Brazilian Amazon has caused serious environmental damage to one of the most complex ecosystems on Earth. Mainly due to the toxicity of mercury to humans, this problem has received wide public attention and prompted many studies. Although these studies have involved sampling of fish, the negative effect of mercury contamination to fish themselves and other wildlife has been largely ignored. To assess the present level of mercury contamination of fish, and its implication for fish and other animals, we collected and examined data on mercury concentration in fish of the Brazilian Amazon, especially for the Tapajós basin, between 1991 and. We conclude that omnivores and piscivores that live nearer to gold mining areas in the Tapajós basin are already at high risk of mercury toxification, especially reproductive failure. Mercury concentrations in these fish are also high enough to have detrimental effects on animals at higher trophic levels. The same conclusion applies to other mercury-contaminated areas in the Brazilian Amazon. Because most Amazonian rivers or their tributaries have favorable conditions for mercury contamination, we can expect the problem to persist in the Amazon for a long time, and the consequences are likely to become more significant in the future. These conclusions have important implications for all tropical rainforests where gold mining operations have caused extensive mercury pollution.Contaminación de Peces por Mercurio y sus Implicaciones para Otras Especies de Vida Silvestre de la Cuenca Tapajós, del Amazonas Brasileño Resumen: Desde 1979, la extracción del oro en el Amazonas brasileño ha ocasionado un daño ambiental serio a uno de los ecosistemas más complejos del mundo. Principalmente debido a la toxicidad del mercurio para los humanos, este problema ha recibido una atención pública amplia y ha impulsado muchos estudios. A pesar de que estos estudios han involucrado el muestreo de peces, el efecto negativo de la contaminación por mercurio en los mismos peces y otras especies de vida silvestre ha sido ignorado. Para evaluar los niveles actuales de contaminación por mercurio en peces y sus implicaciones en otros animales, colectamos y examinamos datos sobre la concentración de mercurio en peces del Amazonas brasileño, especialmente en la cuenca Tapajós, entre 1991 y 1996. Concluimos que los omnívoros y piscívoros que viven más cerca de las áreas de minas de oro en la cuenca Tapajós ya se encuentran en un alto riesgo de intoxicación por mercurio, especialmente en riesgo de falla reproductiva. Las concentraciones de mercurio en estos peces son lo suficientemente altas como para causar un efecto dañino en animales de niveles tróficos más altos. Las mismas conclusiones son válidas para otras áreas del Amazonas brasileño contaminadas con mercurio. Debido a que la mayoría de los ríos del Amazonas o sus tributarios tienen condiciones favorables para la contami- † † Uryu et al. Mercury Contamination of Amazon Fish 439nación por mercurio, podemos esperar que el probl...

Mercury concentration in the freshwater bonefish Cyphocharax gilbert (Curimatidae) and its parasite the crustacean Riggia paranensis (Cymothoidae)

“…The analyses of fish muscle have allowed the assessment of how humans have been exposed to mercury and the evaluation of detrimental effects on animals at higher trophic levels, especially in gold mining areas (Uryu et al, 2001). The mercury concentrations reported in the edible part of the fish collected from several Brazilian freshwater environments varies from 20 ng.g -1 to 700 ng.g -1 in non-piscivorous species and from 60 ng.g -1 to 1,000 ng.g -1 in piscivorous ones (Lacerda et al, 1994;Malm et al, 1995;Lacerda, 1997;Bidone et al, 1997aBidone et al, , 1997bLebel et al, 1997;Moraes et al, 1997;Castilhos et al, 1998;Brabo et al, 1999;De Souza et al, 2000;Lechler et al, 2000;Lima et al, 2000;Leady & Gottgens, 2001;Uryu et al, 2001;Da Silva et al, 2005;Farias et al, 2005;Fostier et al, 2005). The levels of mercury in the edible part of C. gilbert, a nonpiscivorous fish, were close to the lowest values reported for Brazilian fish, suggesting that there is currently a low impact of mercury in the middle Itabapoana River food chains.…”

Advances in the study of giant otter (Pteronura brasiliensis): ecology, behavior, and conservation: a review

“…Gold mining: Most Amazonian rivers or their tributaries have favorable conditions for mercury contamination (Uryu et al, 2001). Even in regions with low anthropogenic presence, mercury concentrations in rivers and lakes are naturally high and mercury bioaccumulation may occur due to the continuous metal release from soils, causing public health problems (Fadini and Jardim, 2001).…”

O comportamento do metilmercúrio (metilHg) no ambiente

“…Para esta região os peixes mais comumente analisados são dourado, jaú, piraíba, mandubé, cachorro, traí-ra, apapa, pescada, tucunaré, filhote, pirarucu, acará, aruana, pacú, surubim, matrinxã, jaraqui, sarda, jiju, jacunda, tambaqui e aracú. As concentrações de Hgtotal para estas espécies em área de mineração variaram de 0,02 até 2,75 mg/kg, sendo que para peixes coletados em rios não contaminados as concentrações variaram de abaixo do Limite de Quantificação até 0,10 mg/kg 20,[27][28][29][30][31][32][33][34][35][36][37][38] . Segundo a literatura os organismos aquáticos apresentam elevada capacidade de absorver os compostos de mercúrio, quer sejam de origem orgânica ou inorgânica.…”