Annual flooding and fish-mercury bioaccumulation in the environmentally impacted Rio Madeira (Amazon)
- 309 Downloads
Regular annual flooding of the Amazonian rivers changes the aquatic environment affecting fish feeding strategies. The Rio Madeira has been greatly impacted by deforestation for agricultural projects, damming for a hydroelectric power plant, and alluvial gold extraction. We studied fish-Hg concentrations within defined weight ranges of representative species at the top of the food web, comparing high and low water seasons. Selected piscivorous species (Cichla spp, Hoplias malabaricus, Pinirampus pirinampu, Serrasalmus spp) showed a large variation of Hg concentrations but only “traíra” (Hoplias malabaricus) showed a statistically significant difference between seasons. However, the bioaccumulation trends during high and low waters were similar for “tucunaré” (Cichla spp) and “traíra” (Hoplias malabaricus) but different for “piranhas” (Serrasalmus spp), “barba chata” (Pinirampus pirinampu) and the detritivorous Prochilodus nigricans. Fish-Hg bioaccumulation is species specific; changes in feeding strategies brought by flooding seasons can change the bioaccumulation pattern without systematically affecting the overall accrual of methylmercury in tertiary consumer species. It appears that naturally occurring Hg and the high sediment load of the Rio Madeira are secondary factors in the Hg bioaccumulation pattern of fish species at the top of the food chain.
KeywordsInundation Floodplain Fish Hg Gold mining
This work was partly supported by the National Research Council of Brazil-CNPq (PPG7, project-556985/2005-2).
- Bastos WR, Malm Olaf, Pfeiffer WC, Cleary D (1998) Establishment and analytical quality control of laboratories for Hg determination in biological and geological samples in the Amazon, Brasil. Ciênc Cult 50:255–260Google Scholar
- CPRM (2002) Companhia de Pesquisa de Recursos Minerais. Serviço Geológico do Brasil—Perspectivas do Meio Ambiente do Brasil; Rio de Janeiro, Brasil, pp 27Google Scholar
- Dorea JG, Barbosa AC, Silva GS (2006) Fish-mercury bioaccumulation as a function of feeding behavior and hydrological cycles of the Rio Negro, Amazon. Comp Biochem Physiol 142:275–283Google Scholar
- Dorea JG, Barbosa AC (2007) Anthropogenic impact of mercury accumulation in fish from the Rio Madeira and Rio Negro Rivers (Amazonia). Biol Tr El Res (in press)Google Scholar
- Goulding M, Carvalho ML, Ferreira EG (1988) Rio Negro: rich life in poor water: Amazonian diversity and floodplain ecology as seen through fish communities. SPB Academic Publishing The Hague, p 200Google Scholar
- Junk WJ (1985) Temporary fat storage, an adaptation of some fish species to the water level fluctuations and related environmental changes of the Amazon River. Amazoniana 9:315–351Google Scholar
- Malm O, Pfeiffer WC, Bastos WR, Souza CMM (1989) Utilização do Acessório de Geração de Vapor Frio para Análise de Mercúrio em Investigações Ambientais por Espectrofotometria de Absorção Atômica. Ciênc Cult 41:88–92Google Scholar
- Malm O, Guimarães JRD, Castro MB, Bastos WR, Viana JP, Branches FJP, Silveira EG, Pfeiffer WC (1997) Follow-up of mercury levels in fish, human hair and urine in the Madeira and Tapajós basins, Amazon, Brazil. Water Air Soil Pollut 97:45–51Google Scholar
- Santos GM, Ferreira EJG, Jegu M (1991) Catálogo dos Peixes do Rio Jamari, Rondônia. Instituto Nacional de Pesquisas da Amazônia/INPA. Manaus, Amazonas, 123Google Scholar