Temporal dynamics of phytoplankton community and physical and chemical variables in the Santander lake (Rionegro, Antioquia, Colombia)

Abstract

Temporal dynamics of physical, chemical and biological characteristics in wet and dry periods in Lake Santander during 1999 was studied. Data were obtained every two weeks in the photic zone in a single sample station. For each physical and chemical variable the minimum and maximum values, the mean and the variation coefficient of were calculated. Only Turbidity and oxygen saturation percentage presented high mean values in the wet period. In this same period, temporal behavior was more dynamic, except the thermal profiles in which a heavy stratification in the dry period were observed.In the community structure Euglenophyta was the key group in the dry period, whereas Chlorophyta was in the wet one. Diversity was mainly explained by dominance and evenness in both periods, due to the change in nitrogen and phosphorus concentrations, and especially, in the ammonium concentration. The community dynamics was independent of the lake conditions in both periods and due possibly to the influence of pluviosity in the trophic condition of the water body.