engleski

Physico-chemical and biological variables of San Jose Creek, Otun River drainage/Upper Cauca , Colombia

A bimodal, nictemeral analysis of San José Creek, a tributary of the Otún River, Upper Cauca was studied. We evaluated physico-chemical and biological variables and applied Shannon-Wiener, Simpson, Margalef and Pielou's biologicaldiversity indices. ANOVA showed that there are significant differences between wet and dry seasons, in surface water temperature, maximum air temperature, pH and conductivity. A total of 1571 macroinvertebrates were collected: 1010 from the rainy season and 561 from the dry. Ephemeroptera was the most abundant taxon in both periods. For phytoplankton we collected 3977 individuals during the wet season and 25093 from the dry. Species of the genus Ankistrodesmus were most abundant during the rainy season (39.02% RA) and Cladophora during the dry (35.16% RA). Vorticella was the most abundant specie of zooplankton in both seasons (82.72% RA wet, 45.10% RA dry). Hemibrycon rafaelense and Bryconamericus caucanus, fishes of the family Characidae, were the most abundant and dominant. Our results indicate that the drainage was oligotrophic in the dry season, but eutrophic during the wet.

bimodal, plankton, invertebrates, fishes

nije evidentirano