Role of microplanktonic species in mercury bioaccumulation in the pelagic foodweb of an ultraoligotrophic lake.

SOTO CÁRDENAS, CAROLINA; GEREA, MARINA; DIEGUEZ, MARIA DEL CARMEN; RIBEIRO GUEVARA, SERGIO; QUEIMALIÑOS, CLAUDIA

Providence

Conferencia; 13th International Conference on Mercury as a Global Pollutant; 2017

In ultraoligotrophic lakes of Andean-Patagonia, the aquatic biota generally bears high total mercury (Hg) levels. In these systems, inorganic Hg (Hg2+) makes up to ~93% of the Hg pool. The microplanktonic fraction (20-200 m) of these lakes is dominated by autotrophic dinoflagellates, (Gymnodinium spp.) and mixotrophic ciliates (Ophrydium naumanni and Stentor araucanus). These organisms may potentially incorporate Hg passively from the dissolved phase and, in the case of the mixotrophic ciliates, also through consumption of picoplanktonic organisms, transferring this metal to higher trophic levels. In this investigation we analyzed the passive and active incorporation of Hg2+ by three basal planktonic organisms of contrasting sizes (increasing size: Gymnodinium spp.