Mercury bioaccumulation in fish of commercial importance from different trophic categories in an Amazon floodplain lake

Abstract

Thirty-two species of commercially important fish from three trophic levels and nine trophic categories were sampled at a floodplain lake of the Solimões River (Lago Grande de Manacapuru). The fish were analyzed to determine their Hg level and the bioaccumulation, bioconcentration, and biomagnification of this element. The observed increase in mean concentration of mercury (49.6 ng.g-1 for omnivores, 418.3 ng.g-1 for piscivores, and 527.8 ng.g-1 for carnivores/necrophages) furnished evidence of biomagnification. Primary, secondary, and tertiary consumers presented biomagnification factors of 0.27, 0.33, and 0.47, respectively. Significant differences in the bioconcentration and concentration of total Hg occurred between the categories of the third trophic level and the other categories. Plagioscion squamosissimus (carnivorous/piscivorous) and Calophysus macropterus (carnivorous/ necrophagous) showed levels of total Hg above those permitted by Brazilian law (500 ng.g-1). Six other species also posed risks to human health because their Hg levels exceeded 300 ng.g-1. Fifteen species showed bioaccumulation, but only eight presented significant correlations between the concentration of Hg and the length and/or the weight of the fish.<br>Trinta e duas espécies de peixes de importância comercial de três níveis tróficos e nove categorias tróficas foram amostradas em um lago de várzea do rio Solimões (Lago Grande de Manacapuru). Os peixes foram analisados para determinar seu nível de contaminação por mercúrio e a bioacumulação, bioconcentração e biomagnificação desse elemento. O aumento na concentração média de mercúrio (49,6 ng.g-1 para os onívoros, 418,3 ng.g-1 para os piscívoros e 527,8 ng.g-1 para os carnívoros/necrófagos) representa evidência de biomagnificação. Consumidores primários, secundários e terciários apresentaram fatores de biomagnificação de 0,27, 0,33 e 0,47, respectivamente. Houve diferença significativa na bioconcentração e na concentração de mercúrio total entre as categorias do terceiro nível trófico e as demais. Plagioscion squamosissimus (carnívoros / piscívoros) e Calophysus macropterus (carnívoros / necrófagos) apresentaram níveis de mercúrio acima do permitido por lei (500 ng.g-1). Seis outras espécies também apresentam riscos para a saúde humana porque seus níveis de mercúrio ultrapassaram 300 ng.g-1. Quinze espécies apresentaram bioacumulação, mas apenas oito apresentaram correlações significativas entre a concentração de mercúrio e o tamanho e/ou o peso do peixe

Mercury: Biogeochemical and Toxicological Aspects and Levels Found in Marine Fish Along the Southern and Southeastern Coasts of Brazil

“…The catfish Cathorops spixii (madamango sea catfish) was used to monitor the sediment of two estuaries in the state of São Paulo, Brazil, the estuary of Santos/São Vicente (impacted area) and the Cananeia estuary (reference area). The results of determination of total mercury in C. spixii confirmed that the estuary of Santos/São Vicente was impacted with mercury (AZEVEDO et al, 2011). Another relevant aspect is the tissue analyzed in fish.…”

“…However, land and ocean processes play an important role in the redistribution of the element in all ecosystems. It is considered a global pollutant that affects the entire freshwater and marine aquatic food web, via biomagnification process (BELTRAN-PEDREIROS et al, 2011;DIETZ et al, 2013). This work discusses various issues related to mercury, including the biogeochemistry, chemistry, and toxicology involved in the presence of this element mainly marine fish.…”

The vulnerability of Amazon freshwater ecosystems

“…Mercury becomes very harmful when anoxic conditions transform its inorganic form into its organic form, methylmercury, which can be absorbed into living tissue and bioaccumulate (Mergler et al 2007). Commercial fishes in the Amazon river have methylmer-cury concentrations higher than that permitted by Brazilian health law (Beltran-Pedreiros et al 2011). A third source of pollution is oil exploration, which has been expanding in the western Amazon (Finer et al 2008; Figure 1).…”

Mercury and methyl mercury in fishes from Bacajá River (Brazilian Amazon): evidence for bioaccumulation and biomagnification

“…M f differed among primary, secondary and tertiary consumers; THg levels in omnivorous species were similar to those in some piscivorous fishes, consistent with results found in Samuel's Reservoir (Rondônia, Brazil) (Kasper et al ., ). In contrast, in the Solimões River, a gradual increase in biomagnification factors from primary to tertiary consumers indicated uniform transfer of mercury (Beltran‐Pedreros et al ., ).…”