FIRST REPORT OF GYMNODINIUM SP. (DINOPHYCEAE) BLOOM IN A NEOTROPICAL RIVER OF ARGENTINA

Gualeguaychú river is a freshwater continental located in the Center-Eastern of Argentina corresponding to the Neotropical region. Several uses can be identified such as the conservation of aquatic life, recreation (primary and secondary contact), navigation, recreational and subsistence fishing, and human and animal consumption. From February to April 2018, a bloom of Gymnodinium sp. (Dinophyceae) was reported in the low basin of the Gualeguaychú river. The bloom was extended from the Parque Unzué (33º 00' 16.38" S - 58º 29' 21.15" W) to the discharge of the El Cura stream (33º 02' 27.00" S - 50º 20' 29.01" W). This was the first record of a bloom of Gymnodinium sp. in that region where potentially toxic cyanobacteria blooms usually have an annual frequency. Consequently, this finding could be interpreted as a global indicator of change. Therefore, it is necessary to advance in systematic monitoring to develop an early warning system in the Gualeguaychú River.