Phytoplankton Richness in the Gastona River (Tucuman, Argentina)

Diatoms

Abstract

The aim of this paper was to contribute to the knowledge of? diatoms found in the Gastona River (Tucumán, Argentina) in 1994 and 1998-1999. Five places of samplings were selected along the river (coincident three of them with 1994) based on the area of discharge of the effluents from a sugarcane industry and sewage. The first two places were located before the discharges of pollutants and the other three downstream the same ones. The diatoms contributed. with more than 50 % of all the species present in the phytoplankton in both periods studied. The pennate diatoms prevailed over the centric ones, which characterize to rivers -of low -order. We described for the first time from the Argentinean Northwest six-species and six varieties: Achnanthes minutissima var. affinis (Grunow) Lange-Bertalot, Amphora ovalis (Kützing) Kützing, Diploneis ovalis (Hilse) Cleve, Eunotia dydima var. claviculata Hustedt, Fragilaria capucina var. mesolepta (Rabenhorst) Rabenhorst, Frustulia vulgaris (Thwaites) De Toni, Navicula amphibola Cleve, N. goeppertiana var. dapalis (Frenguelli) Lange-Bertalot, Nitzschia gracilis Hantzsch, Pinnularia divergens W. Smith, P. gibba var. linearis Hustedt, Surirella brebissonii var. kuetzingii Krammer & Lange-Bertalot.