Physicochemical and biological characterization of the Roble river, upper Cauca, western Colombia

Abstract

To determine dial and seasonal differences as well as productivity and the trophic status of the lower Roble river, a tributary of the Vieja and upper Cauca rivers of west Colombia, we sampled phytoplankton, zooplankton, fish and macroinvertebrates and recorded physicochemical variables (dissolved oxygen, percent oxygen saturation, pH, conductivity, relative humidity, environmental, water, maximum and minimum temperatures, width, depth, current velocity, substrate, CO2, COD, BOD, total calcium and magnesium hardness, total, dissolved and suspended solids, alkalinity, acidity, chlorine and turbidity) during the wet and dry seasons. Most physicochemical variables such as relative humidity, dissolved oxygen and percent oxygen saturation showed low coefficients of variation, except for oxygen deficit. The Shannon-Wiener diversity index, equity and dominance had low values around 0.5. We recorded eight orders, 28 families and 58 genera of macroinvertebrates, three divisions, five orders and 45 genera of phytoplankton, two divisions and six genera of zooplankton and 19 species of fishes. This river has an allochthonous-heterotrophic trophic state and productivity is oligotrophic but with a tendency to eutrophication.