Resumen

MIRANDE, V.  y  TRACANNA, B. C.. Phytoplankton from an ArgentineanNorwestRiver contaminated by sewage and sugarcane effluents. Bol. Soc. Argent. Bot. [online]. 2005, vol.40, n.3-4, pp.169-182. ISSN 1851-2372.

Gastona River is one of the tributaries more contaminated from Río Hondo Dam (Tucumán-Santiago del Estero). This river presents in sugarcane activity period (June-October) anoxic conditions and alterations of nitrogen and phosphoric components, between others causes. The aim of this paper was to characterize the water quality in agreement to species groups and densities of phytoplankton found in 1998-1999. We were selected five sampling sites along the river in relation to sewage and industry effluents discharge areas. Sampling were realized monthly and during thirteen months. We began the sampling on March. Indices employed were: Composite; Species Deficit; Pampeano Diatom Index; Euglenal; Centrales/Pennales; Chlorophyta/Chrysophyta (diatoms) and Density-Species Relations. The results obtained showed that Chlorophyta were the group most sensitive to organic mater effects. The four first indices commented previously were the most effective to differentiate between not-sugarcane activity period and sugarcane activity period.

Palabras clave : Phytoplankton; Species; Algal indices; Contamination; Sugarcane activity; Sewage; Gastona River.

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