Mercury in Populations of River Dolphins of the Amazon and Orinoco Basins

This study reports the presence of mercury in river dolphins ’ generaInia andSotalia. Mercury concentrations were analysed in muscle tissue samples collected from 46 individuals at the Arauca and Orinoco Rivers (Colombia), the Amazon River (Colombia), a tributary of the Itenez River (Bolivia) and from the Tapajos River (Brazil). Ranges of total mercury (Hg) concentration in muscle tissue of the four different taxa sampled were:I. geoffrensis humboldtiana 0.003 –3.99 mg kg−1 ww (n = 21,Me = 0.4),I. g. geoffrensis 0.1 –2.6 mg kg−1 ww (n = 15,Me = 0.55),I. boliviensis 0.03 –0.4 mg kg−1 ww (n = 8,Me = 0.1) andS. fluviatilis 0.1 –0.87 mg kg−1 ww (n = 2,Me = 0.5). The highest Hg concentration in our study was obtained at the Orinoco basin, recorded from a juvenile male ofI. g. humboldtiana (3.99  mg kg−1 ww). At the Amazon basin, higher concentrations of mercury were recorded in the Tapajos River (Brazil) from an adult male ofI. g. geoffrensis (2.6  mg kg−1 ww) and the Amazon River from an adult female ofS. fluviatilis (0.87  mg kg−1 ww). Our data support the presence of total Hg in river dolphins distributed across the evaluated basins, evidencing the role of these cetaceans as sentinel species and bioindicators of the presence of this heavy metal in natural aquatic environments.
Source: EcoHealth - Category: Environmental Health Source Type: research