PHYTOPLANKTON COMMUNITY IN IKHIOGBE AND ORHIONMWON RIVERS

ABSTRACT

Phytoplankton are free-floating, photosynthetic, aquatic plant-like microorganisms, which move from one place to another, either actively by their locomotory organs (flagella) or passively by water currents. This study gives insight into the composition, abundance and diversity of phytoplankton community in Ikhiogbe River and Orhionmwon River. The physiochemical parameters and phytoplankton samples were collected once a month for six months, phytoplankton were collected using the filter sieve of 0.05mm, Air and surface water temperature were measured in situ using mercury-in-glass thermometer, pH and conductivity were measured using a multi-meter, Water transparency and depth were determined using a Secchi disc. The estimated values for PH, conductivity, dissolved oxygen and biological demand were within the range of most tropical freshwater bodies. A total of 21 species of phytoplankton were identified from in Orhionmwon and Ikhiogbe rivers during the period of study. Most of them were Chlorophyta (11 species), Charophyta (2 species), Cyanophyta (3 species), Bacillariophyta (3 species) Rhodophyta (2 species) and Euglenophyta (1 species). The abundance, composition and distribution of the phytoplankton in Ikhiogbe River and Orhionmwon River is affected by the environmental variables.The population of phytoplankton was generally higher in the river system during the study period. This leads to the conclusion that the Ikhiogbe River and Orhionmwon River is rich in taxa during the dry season and it also shows that primary productivity is high in Ikhiogbe River and Orhionmwon River during the dry season.