OCCURRENCE AND TOXICITY OF CYANOBACTERIAL BLOOMS IN PARANÁ RIVER (ARGENTINA), DOWNSTREAM OF THE YACYRETÁ RESERVOIR.

MARINA FORASTIER; DANIELA SEDAN; DARIO ANDRINOLO ; YOLANDA ZALOCAR

Estambul

Congreso; The 8th International Conference on Toxic Cyanobacteria (ICTC8); 2010

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Background and aims The Paraná river basin is the second largest catchment of South America, shared by Brazil, Bolivia, Paraguay and Argentina. The construction of Yacyretá on High Paraná, one of the largest impoundments built in Argentina, was finished in 1990-1994. The first bloom of Microcystis aeruginosa (Kütz) was registered in summer 2004 (Kütz in the river Paraná) In this work we present a study of abundance and toxicity of blooms of M. aeruginosa 220 km downstream from the Yacyretá reservoir (27º28'16"S; 58º51'07"O) between 2004 and 2008. Methods. To the study of the phytoplankton, it was taken monthly qualitative and quantitative samples. To determinate toxicity, the samples were taken in summer, from the year 2005 until 2008. These samples were tested by mouse bioassay and high-performance liquid chromatography (HPLC) with diode-array detector. The major density of M. aeruginosa was in summer all years, (with 189-3x104 cél.ml-1), and with mean volume of 5 mm3.L-1.   The analyses of the samples showed hepatotoxicity in the tests with mice. Five variants of microcystins were detected: LR, LA, RR, YR and XR. LR was better represented every year in concentrations between 3 and 185 ppm of lyophilised cells. This is the first report of microcystins in the Paraná river (Argentina) during blooms de M. aeruginosa.