The algae diatoms present were distributed in various aquatic environments and respond quickly to environmental changes, they’have bee used as indicators of organic pollution and eutrophication. The responses are known of many taxa to environmental changes and tolerance to water chemistry and pH, as well as resistance to organic pollution (saprophytic). In order to deepen the study of diatoms in stream Caranã, Boa Vista – RR, this study had as objective to evaluate the quality of water in stream Caranã, using physico-chemical and biological. During the dry season (November and December 2009, and January 2010), and the rainy season (April, May and June 2010) samples were made of epiphytic diatoms were collected at four points along the stream Caranã, where the material was oxidized and, then permanently placed on slides. We determined the pH and water temperature, as well as water collection for microbiological analysis. 90 taxa were recorded, at specific level, divided into 20 genera and 13 families. The most widely represented families were Eunotiaceae and Pinnulariaceae. Eunotia and Pinnularia genera had 28 and 14 taxa, respectively. A total of 24 species were considered abundant: Actinella mirabilis (Eulenstein ex Grunow) Grunow, Brachysira rostrata (Krasske) Lange- Bertalot and Metzeltin, Brachysira sp., Encyonema perminutum Krammer, Encyonopsis Frequentis Krammer, Eunotia cf. bilunaris (Ehrenberg) Mills, E. incisa Gregory var. incisa, E. luna var. aequalis Hustedt, E. paludosa Grunow aff, paludosa, E. synedraeformis var. angustata Hustedt, E. trasfuga, E. yanomami and Lange-Bertalot Metzeltin, Fragillia javanica Hustedt, Frustulia rhomboide (Ehernberg) De Toni var. rhomboide, F. saxonica Rabenhorst, F. undosa, Frustulia sp., Gomphonema archeavibrio Lange-Bertalot; Reichardt, G. lagenula Kützing, Luticola monita (Hustedt) D.G. Mann, Pinnularia brauniana (Grunow) Mills, P. divergens W. Smith (sensu lato), Stenopterobia delicatissima (Lewis) Van Heurck sensu lato, Surirella linearis var. constricta Grunow. All species featured along with the pH data corroborate the literature, where it is considered, therefore, the waters of the stream Caranã, the presence and abundance of Eunotia and Pinnularia, and tropical, oligotrophic and acidic. The species found in the study are first cited in the State of Roraima.
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