Phytoplankton community of the Itaya river basin in Loreto, Peru

The phytoplankton community was evaluated in 21 samples collected in seven sites in the Itaya river basin. In total, 70 species belonging to 40 genera, 21 families and 6 divisions were identified. The most abundant group was Bacillariophytas (51%), followed by Chlorophytas (31%), Euglenophytas (11%), Cyanophytas (5%), and others (2%) corresponding to Xanthophyta and Chrysophyta. The best represented species were Surirella ovalis, Navicula sp and Pinnularia sp. For this ecosystem, the density was between 100 to 13 000 ind/l-1 (individuals per litre) out of a total of 24 500 ind/l-1, with a richness of 11 to 27 species and an abundance of 23 to 55 individuals. The analysis of diversity according to Shannon-Wiener was from 7.26 to 25 units of effective species, with an equity of Pielou of 0.84-0.97, which indicates that the populations were homogeneous. Regarding the similarity index, it shows that the phytoplankton communities were formed by three groups with a similarity of 35%. According to the diatomic index (IDG), it is concluded that the water of the Itaya river could be contaminated at the sampling points.