title: Mercury and selenium in tropical marine plankton and their trophic successors.
abstract: Selenium (Se), mercury (Hg) and methylmercury (MeHg) were determined in microplankton (⩾25μm), crustacean muscle tissue, in the muscle and liver of two fish species and tissues of a dolphin from a bay in the Brazilian Southeast coast. Differences were found between the fish and dolphin muscle and hepatic concentrations. Liver showed the highest concentrations of Se and Hg. Positive biotransference of MeHg from source to consumer was observed for all interactions, demonstrating that MeHg biomagnified along the food web. The pelagic food chain has the highest biomagnification potential when compared to the benthic system. A large excess of Se in relation to Hg was observed in all tissues. The muscle and liver of the predator species, the dolphin and the carnivorous fish, presented similar MeHg. The predator species presented similar MeHg to Hg (% MeHg) ratios in muscle tissues (∼100%), whereas dolphin showed lower hepatic% MeHg (18) than the carnivorous fish (69%). Iliophagous fish presented the lowest % MeHg in tissues. Fish showed a positive relationship between hepatic MeHg and Se, whereas % MeHg did not change with increasing Se:Hg molar ratios in liver. Dolphins showed a significant inverse relationship between hepatic MeHg and Se and the % MeHg and Se:Hg ratios. This suggests a strong antagonistic effect of Se on MeHg assimilation and accumulation in this species. Probably, the differences observed among Hg as MeHg and Se and on the effect of Se on MeHg assimilation and accumulation in all marine species are related to the physiological differences between dolphins and fish.
authors.affiliation: Dep. de Química, Pontifícia Universidade Católica do Rio de Janeiro, 22453-900 Rio de Janeiro, Brazil. Electronic address: terciaguedes@gmail.com.
authors.forename: Tércia
authors.initials: T
authors.lastname: Guedes Seixas
authors.affiliation: Dep. de Química, Pontifícia Universidade Católica do Rio de Janeiro, 22453-900 Rio de Janeiro, Brazil. Electronic address: isabel@puc-rio.br.
authors.forename: Isabel
authors.initials: I
authors.lastname: Moreira
authors.affiliation: Dep. de Endemias, Escola Nacional de Saúde Pública/Fiocruz, 21041-210 Rio de Janeiro, Brazil. Electronic address: sal@ensp.fiocruz.br.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Siciliano
authors.affiliation: Lab. de Radioisótopos Eduardo Penna Franca, IBCCF, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, RJ, Brazil. Electronic address: olaf@biof.ufrj.br.
authors.forename: Olaf
authors.initials: O
authors.lastname: Malm
authors.affiliation: Lab. de Radioisótopos Eduardo Penna Franca, IBCCF, Universidade Federal do Rio de Janeiro, 21941-902 Rio de Janeiro, RJ, Brazil; Lab. de Ciências Ambientais, Universidade Estadual do Norte Fluminense, 28013-602 Campos dos Goytacazes, RJ, Brazil. Electronic address: helena.kehrig@pesquisador.cnpq.br.
authors.forename: Helena Amaral
authors.initials: HA
authors.lastname: Kehrig
mesh_terms: D000818:Animals; D004289:Dolphins; D005399:Fishes; D020387:Food Chain; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis; D009132:Muscles / Q000737:chemistry / Q000378:metabolism; D010933:Plankton / Q000737:chemistry* / Q000378:metabolism; D012643:Selenium / Q000032:analysis*; D013054:Spectrophotometry, Atomic; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury; D012643:Selenium
keywords: Bioaccumulation; Coastal mammal; Fish; Mercury–selenium relationship; Methylmercury; Plankton