Genotoxicity of mercuric chloride in two ictic species (Prochilodus magdalenae and Oreochromis sp.)

Abstract

The micronucleus (MN) genetic test in fish blood cells has been used as a reliable technique, for the in vivo evaluation of genotoxicity and in situ biomonitoring of water quality in continental ecosystems. 

This research was conducted with the purpose to evaluate the usefulness of a native and introduced ictic specie to Colombia (Prochilodus magdalenae and Oreochromis sp, respectively), to evaluate genotoxicity of a common water pollutant (mercury chloride) under controlled conditions.

Three lots of fish, each containing twenty individuals were exposed to sublethal concentrations of HgCl₂ (0.001, 0.003,0.027 mg/l). A fourth lot of untreated individuals was included as control.

Cytogenetic slides were prepared each day from both gills from two individuals and the average number of MN/1.000 erythrocytes was recorded. Results indicate a clear dosage and exposure time effect (p < 0.05 to p < 0.0001). Furthermore,the results evidenced that the native species (bocachico), is more sensitive to HgCl₂ genotoxicity than tilapia (Oreochromis sp.). Therefore, we recommend the use of bocachico as a potential centinel species for the biomonitoring of water contaminants, particularly  in  hydrographic  valleys  predominantly  inhabited  by  this  species  and/or  polluted  by  this  common  water contaminant.