PHYTOPLANKTON COMMUNITY ASSEMBLAGE

ABSTRACT

This study gives insight into the composition, abundance and diversity of phytoplankton community in Amagba-Okoroma River. The scope of this study was to determine the water quality and taxonomic composition, relative abundance and distribution of phytoplankton community in Amagba-Okoroma River. The physicochemical parameters and phytoplankton samples were collected seasonally and analyzed according to standard methods. Phytoplankton were collected using a filter sieve plankton net with a mesh size of 0.55µm and analyzed to the lowest possible taxonomic level. A total of 18 species of phytoplankton were recorded during the study. These species belonged to the Chlorophycae (n = 14), Cyanophyceae (n = 2), Euglenoidea (n = 3), Bacillariophycae (n = 1) and Pyrrhophyceae (n =1), but phytoplankton density was low. The dominant species were Spirogyra hopeiensis and Spirogyra varians. Diversity indices revealed higher species richness, Margalef, Shannon index in station 1, followed by station 2 and then station 3. Results from the seasonal variation showed that phytoplankton abundance in Amagba-Okoroma River increases during the dry season and decreases during the wet seasons due to some influencing factors. Correlation matrix revealed strong relationship between the principal physicochemical parameters and some phytoplankton species. The distribution, composition and abundance of phytoplankton in Amagba-Okoroma River was affected by the environmental variables, and also greatly influenced by the seasons and that the phytoplankton species in AmagbaOkoroma River was low.