STUDY OF THE PHYTOPLANKTON POPULATION IN THE MBOI KA E STREAM, ENCARNACION, PARAGUAY.

The study was conducted during the four seasons of 2015 in the water basin of the Mboi Ka'e stream in the city of Encarnaci?n. The objective of the research was to evaluate the phytoplankton population in the Mboi Ka e watershed in the four seasons of the year. The samples were collected in six different points included within the study area, in each of the seasons of the year by means of the water filtration method through an aperture mesh network of 25 ?m were fixed with 5% formaldehyde. The analyzes were carried out in the laboratory of the Faculty of Science and Technology of the State University of Itap?a with 10x, 40x, 100x optical microscope. For these, Sedwick-Rafter camera was used by random fields or bands. In the study, three classes of phytoplankton Cyanophyta, Chlorophyta and Bacillariophyta were identified. An analysis of variance (ANOVA) was performed for each class identified in the four seasons of the year. The ANOVA presented a significant difference for the Cyanophyta class in relation to the seasons, the Chlorophyta class showed no significant difference for the seasons as for the number of individuals (cells, colonies or filaments) while the Bacillariophyta class presented a difference not significant for the seasons of the year while the difference was highly significant for the number of cells. Results yielded that in the watershed of the Mboi Ka\\\\\\\'e stream, the phytoplankton population is dominated by three main classes, Cyanophyta, Chlorophyta and Bacillariophyta.