The plankton of Odot Stream, Niger Delta, Nigeria were investigated between June and August, (wet season) and October - December, 2014 (dry season) using standard analytical procedures. The data generated were subjected to descriptive statistics and community structure analysis. A total of 37 species of Phytoplankton belonging to four taxa were identified in ascending order as follows: Xanthophyceae (4.7%), Baccillariophyceae (20.19%), Cyanophyceae (36.34%) and Chlorophyceae (38.71%). Zooplankton belonging to 4 taxa were also identified in ascending order as follows; Cladocera (11%), Copepoda (11%), Larvae (26%), Rotifera (52%). Higher seasonal abundance among the families were recorded in dry season for Chlorophyceae (39.16±14.75), Cyanophyceae (21.83±6.50) and Xanthophyceae (10.66±5.81) while higher wet seasonal abundance were recorded for Baccillariophyceae (22.25±4.59) and Copepoda (0.58± 0.34). Chlorophyceae and Rotifera were found as the dominant group in this present study and indicated that Odot stream was highly productive (eutrophic), which could be attributed to high temperature due to the shallowness of the stream and its high exposure to sunlight. Excessive algal bloom should, therefore, be checked to prevent the stream from anoxia and poor water quality and shift in species composition and fish kill.
Key words: Odot Stream, phytoplankton, zooplankton, abundance, Bacillariophyceae, Rotifera