CONICET | Buscador de Institutos y Recursos Humanos

Microalgae are photoautotrophic oxygen evolving microorganisms which includes: Chlorophyceae, Cyanophyceae and Bacillariophyceae. They are morphologically diverse and present extensive distribution. Microalgae reflect a wide range ofphysiological properties and they are tolerant to environmental stress. Therefore, they have been widely used as model species to evaluate different environmental stressors in ecotoxicological tests. The microalgae Oocystis sp. is one of the numerous planktonic green algae, usually of reservoir waters. It has characteristics of a model species: rapid growth and it is easy to handle in laboratory conditions. Our goal is to propose to Oocystis sp. as a model species for ecotoxicological tests. The samples of the microalgae werecollected with a phytoplankton net from temporary puddles in ―El Volcán‖ town in San Luis province. In the laboratory, the organisms were kept in Bold´s Basal Medium (BBM). The initial biomass (6 106 cells mL-1) was exposed to contaminants such as polybrominated biphenyls (BDE-209) which toxicity is known, for 96 h. Cell count examination was performed using Neubauer chamber under Optic Microscope (400X). Chlorophyll stress index and oxidative stress enzymes (ROS) were determined with spectrometry. Oocystis sp. showed sensitivity with a 50% growth inhibition with respect to the control from 100 µg L-1 of BDE-209. Catalase activity increased with values greater than 100 µg L-1 of BDE-209; while TBARS showed differences only in algae exposed at 100 µg L-1of BDE-209. Chlorophyll showed signs of stress and senescence from 100 µg L-1 BDE-209 (value 0.03 mg g-1). Oocystis sp. showed toxicity response, which provides relevant information about sensitivity, and they can be used as a model inenvironmental risk studies to BDE-209.