Mercury bioaccumulation in fishes of a paddy field in Southern of Brazil

Bioacumulação de mercúrio em peixes em uma lavoura de arroz no Sul do Brasil

Aim: The aim of present study was to evaluate the Hg concentration in two species of fish (Astyanax sp and Corydoras paleatus) and its potential use as a biomonitor, in order to know if the use of pesticides and fertilizers in paddy can enhance the Hg contamination to adjacent aquatic environment.

Methods

Soil, suspended particulate matter and fish samples were sampled in a paddy field in South Brazil_. A cold vapor system, coupled with a GBC 932 atomic absorption spectrophotometer was used for total Hg determinations in samples.

Results

The paddy soil shows Hg concentration 2-fold higher (mean 31 ng g^-1) in comparison to background areas (not cultivated). Suspended particle matter Hg concentration in paddy channels (mean 232.5 ± 44.2 ng g^–1) are 1.5 times higher than the regional background. The analyzed fish specimens Astyanax sp in paddy showed Hg concentration 4-fold higher and significant different to background area. The mean Hg concentration in fish was: 51.7 ± 19.5 ng g^–1 in Astyanax sp and 156.8 ± 44.0 ng g^–1 in Corydoras paleatus.

Conclusions

Considering the linear regression and Man whitney test hypothesis to Hg concentration in fish tissue from paddy suggests that Astyanax sp. can be a good biomonitor of Hg contamination, whereas Corydoras paleatus is a potential biomonitor. However, more studies with Corydoras are necessary in order to aggregate consistency to this hypothesis.

biomonitoring; fish; mercury; contamination; Pampa biome