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Biofilm and mercury availability as key factors for mercury accumulation in fish ( Curimata cyprinoides ) from a disturbed amazonian freshwater system
Author(s) -
Dominique Yannick,
MauryBrachet Régine,
Muresan Bogdan,
Vigouroux Régis,
Richard Sandrine,
Cossa Daniel,
Mariotti André,
Boudou Alain
Publication year - 2007
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/05-649r.1
Subject(s) - mercury (programming language) , methylmercury , bioaccumulation , environmental chemistry , anoxic waters , environmental science , organic matter , food chain , hypolimnion , ecology , water column , chemistry , nutrient , biology , eutrophication , computer science , programming language
The Petit‐Saut hydroelectric reservoir was filled in 1994 on the Sinnamary River in French Guiana (Amazonian basin). Flooding of the equatorial rain forest led to anoxia in most of the water column and enhanced mercury methylation in the reservoir hypolimnion. We selected the benthivorous/omnivorous fish species Curimata cyprinoides to investigate total mercury and methylmercury (MeHg) bioavailability and bioaccumulation capacities in the reservoir and downstream in the Sinnamary River. Mercury concentrations in the dorsal skeletal muscle were 10‐fold higher in fish from the downstream zone. Stomach contents and stable nitrogen and carbon isotope ratios showed that biofilms and the associated invertebrate communities represented important food sources at the two sites. The δ 13 C measurements indicated that biofilms in the flooded forest zone of the reservoir consist of endogenous primary producers; downstream, they are based on exogenous organic matter and microorganisms, mainly from the anoxic layers of the reservoir. Total mercury and MeHg concentrations in the biofilms and associated invertebrates were much higher at the downstream site compared to concentrations at the reservoir. Our results clearly show the importance of MeHg export from the anoxic layers of this tropical reservoir. We conclude that differences between biofilm composition and MeHg concentrations in the ingested food could explain the marked differences observed between mercury levels in fish.