Limnetica 40

The proliferation of the freshwater dinoflagellate Ceratium furcoides (Levander) continues to escalate within South America. Early detection and the subsequent monitoring of this non-indigenous species are essential mitigation polices in the basins at potential risk. A combination of these policies with a better understanding of the dinoflagellate's environmental habitat would thus, assist in reducing possible impacts on the highly diverse aquatic biodiversity of this region. The invasive dinoflagellate can now be found in the tropical reservoirs of three hydroelectric power plants, which extends its presence over a distance of ~500 km along the Paraíba do Sul eco-region in southeastern Brazil. Less than favorable water management strategies between river basins have probably accelerated this expansion. Water residence time has also most likely influenced the presence and abundance of C. furcoides. The smallest recorded size of C. furcoides reported in the literature (51-68 μm length, 14-16 μm width) was detected in the reservoir with the lowest water residence time, this indicates a probable adaptation of this invader to water current. The variety of environmental conditions in which C. furcoides was found reinforces the assumption that it is a highly eurytopic species. Despite there being no evidence of blooms, the invasiveness of C. furcoides suggests that other nearby aquatic systems throughout Paraíba do Sul and Guandu river basins may indeed already harbor populations of C. furcoides. This scenario heightens the urgency to formulate a monitoring program with an integrated and predictive approach on a regional scale as millions of people depend economically upon these river systems and importantly, for water supply.