PHYTOPLANKTON RICHNESS OF LA CAÑADA STREAM (GUALEGUAYCHÚ, ENTRE RÍOS)

Abstract

The  current  deterioration rate  of watercourses  in  the  Pampas  ecoregion  is alarming  and  endangers  the  quality  of its  waters  and  biodiversity,  therefore   diffusion  of knowledge on the subject is essential and urgent. La Cañada Stream is located in the basin of the Gualeguaychú  River,  surrounded by an area of agricultura! and livestock activity.  During 2014-2015, the richness  of phytoplankton was studied in its lower basin and physiochemical parameters. Twenty-five  genera  representatives  of divisions  Bacil!ariophyceae (19),  Chlorophyta (3),  Charophyta  (1)  and Euglenophyta  (2) were found, the first of these being the dominants in the study period. The average of the phisico-chemical  parameters were: temperature 17.19 ºC; pH  7.12;  dissolved  oxygen 4.40 mg/L;  electrical conductivity  245.75 µS/cm;  total nitrogen 6.99 mg/L; total phosphorus 1.12 mg/L and chemical oxygen demand  40.67 mgO2/L. The study area ranged  from eutrophic  to hypereutrophic,  showing relatively high organic  matter and low oxygen values. This work was the first report  on the richness of phytoplankton in La Cañada Stream and middle-lower basin of the Gualeguaychú  River.