title: Mercury biomagnification and the trophic structure of the ichthyofauna from a remote lake in the Brazilian Amazon.
abstract: The present study assesses mercury biomagnification and the trophic structure of the ichthyofauna from the Puruzinho Lake, Brazilian Amazon. In addition to mercury determination, the investigation comprised the calculation of Trophic Magnification Factor (TMF) and Trophic Magnification Slope (TMS), through the measurements of stable isotopes of carbon (δ13C) and nitrogen (δ15N) in fish samples. These assessments were executed in two different scenarios, i.e., considering (1) all fish species or (2) only the resident fish (excluding the migratory species). Bottom litter, superficial sediment and seston were the sources used for generating the trophic position (TP) data used in the calculation of the TMF. Samples from 84 fish were analysed, comprising 13 species, which were categorized into four trophic guilds: iliophagous, planktivorous, omnivorous and piscivorous fish. The δ13C values pointed to the separation of the ichthyofauna into two groups. One group comprised iliophagous and planktivorous species, which are linked to the food chains of phytoplankton and detritus. The other group was composed by omnivorous and piscivorous fish, which are associated to the trophic webs of phytoplankton, bottom litter, detritus, periphyton, as well as to food chains of igapó (blackwater-flooded Amazonian forests). The TP values suggest that the ichthyofauna from the Puruzinho Lake is part of a short food web, with three well-characterized trophic levels. Mercury concentrations and δ13C values point to multiple sources for Hg input and transfer. The similarity in Hg levels and TP values between piscivorous and planktivorous fish suggests a comparable efficiency for the transfer of this metal through pelagic and littoral food chains. Regarding the two abovementioned scenarios, i.e., considering (1) the entire ichthyofauna and (2) only the resident species, the TMF values were 5.25 and 4.49, as well as the TMS values were 0.21 and 0.19, respectively. These findings confirm that Hg biomagnifies through the food web of Puruzinho Lake ichthyofauna. The migratory species did not significantly change mercury biomagnification rate in Puruzinho Lake; however, they may play a relevant role in Hg transport. The biomagnification rate (TMS value) in Puruzinho Lake was higher than the average values for its latitude, being comparable to TMS values of temperate and polar systems (marine and freshwater environments).
authors: Laboratório de Radioisótopos Eduardo Penna, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Av. Carlos Chagas Filho s/n, bloco G, Sala 60, Subsolo, Ilha do Fundão, Rio de Janeiro, RJ, Brazil. Electronic address: ceass@biof.ufrj.br.
authors: Claudio Eduardo
authors: CE
authors: Azevedo-Silva
authors: Instituto Natureza e Cultura, Universidade Federal do Amazonas, Rua 1 de Maio. Colegiado de Ciências Agrárias, Benjamin Constant, Colônia, AM, Brazil.
authors: Ronaldo
authors: R
authors: Almeida
authors: Laboratório de Radioisótopos Eduardo Penna, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Av. Carlos Chagas Filho s/n, bloco G, Sala 60, Subsolo, Ilha do Fundão, Rio de Janeiro, RJ, Brazil.
authors: Dario P
authors: DP
authors: Carvalho
authors: Instituto Nacional de Pesquisas Espaciais, Centro de Ciências do Sistema Terrestre, Avenida dos Astronautas, 1758, Jardim da Granja, São José dos Campos, SP, Brazil.
authors: Jean P H B
authors: JPHB
authors: Ometto
authors: Laboratório de Ecologia Isotópica, Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Avenida Centenário, 303, São Dimas, Piracicaba, SP, Brazil.
authors: Plínio B
authors: PB
authors: de Camargo
authors: Laboratório de Radioisótopos Eduardo Penna, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Av. Carlos Chagas Filho s/n, bloco G, Sala 60, Subsolo, Ilha do Fundão, Rio de Janeiro, RJ, Brazil.
authors: Paulo R
authors: PR
authors: Dorneles
authors: Núcleo de Estudos de Saúde Coletiva, Universidade Federal do Rio de Janeiro, Avenida Horácio Macedo, S/N, Ilha do Fundão, Rio de Janeiro, RJ, Brazil.
authors: Antonio
authors: A
authors: Azeredo
authors: Laboratório de Biogeoquímica Ambiental - Universidade Federal de Rondônia, Br 364km 9,5. Sentido Acre, Porto Velho, RO, Brazil.
authors: Wanderley R
authors: WR
authors: Bastos
authors: Laboratório de Radioisótopos Eduardo Penna, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Av. Carlos Chagas Filho s/n, bloco G, Sala 60, Subsolo, Ilha do Fundão, Rio de Janeiro, RJ, Brazil.
authors: Olaf
authors: O
authors: Malm
authors: Laboratório de Radioisótopos Eduardo Penna, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Cidade Universitária, Av. Carlos Chagas Filho s/n, bloco G, Sala 60, Subsolo, Ilha do Fundão, Rio de Janeiro, RJ, Brazil.
authors: João P M
authors: JPM
authors: Torres
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000378:metabolism; D005399:Fishes / Q000378:metabolism*; D020387:Food Chain; D008628:Mercury / Q000378:metabolism*; D009587:Nitrogen Isotopes / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D008628:Mercury
keywords: Fish; Mercury; Migration; River-floodplain system; Trophic magnification factor