PERIPHYTIC DIATOMS OF LAKES WITH DIFFERENT TROPHIC STATE IN THE DEPARTMENT OF CAUCA (COLOMBIA)

The presence and absence of Phyto-periphytic species have been used as indicators of trophic state of the aquatic systems, among which diatoms are emphasized. That situation and the lack of information for the department of Cauca, brought to the evaluation of three lakes with different trophic state and the performance of a adhered periphyton scrape in the plates established .. Samples were taken form the internal, medium and outer parts of each plate. The collected sample was preserved in Lugol-acetic acid. The lakes showed differences in the physicochemical characteristics of water, which determined the trophic state of each. According to this, the established ranges for nitrites, nitrates and total phosphorus, typified Lake 1 as oligotrophic, Lake 2 as meso-oligotrophic and Lake 3 as eutrophic. Diatoms predominated in all lakesbut the Lake 3 differs from the other lakes in the high dominance of the number of species and greater abundance of Gomphonema, a condition that is reflected in low values for Pielou equitability index.