Estimation of Quality of Water of Lake Virua (Albania) based on Analysis of Diatoma

The main objective of this paper is to investigate the genera of diatoms, which were identified in the Viroi lake in the period 2011-2012 in the Gjirokastr region. We also carried out a classification of the quality of the water through the bio-indicator diatoms. The presence of polysaprobic species in theVirua lake, such as, Gomphonema parvulum, G. olivaceum, Nitzschia palea, is a clear indication of the pollution of waters coming from a variety of source. According to the bio-indicator saprobic species investigated the waters in the Virua lake Is classified as II class of bonity, i. e. from oligomesosaprob to betamesosaprob level.