SEASONAL DYNAMICS OF PHYTOPLANKTON DIVERSITY IN RELATION TO CHLOROPHYLL CONTENTS IN AJIWA RESERVOIR.
Seasonal changes in phytoplankton diversity in relation to chlorophyll contents in Ajiwa reservoir, Katsina State Nigeria was carried out from June 2019 to January 2020 using standard procedures. Three (3) sampling stations were chosen. The phytoplankton and chlorophyll content of the water was determined using the standard method (APHA 1999). The results from the three sites indicated mean phytoplankton percentage composition of Chlorophyceae (33.50%), Bacillariophyceae (22.36%), Cyanophyceae (12.57%), Chryptophyceae (12.48%), Chrysophyceae (7.93%), Euglenophyceae (6.58%), and dinophyceae (4.55%). There were significant differences between season and phytoplankton abundance with more diversity of phytoplankton recorded in the wet season than the dry season. The highest was Chlorophyceae it has a total number of 397 individual species which represent 33.50% of the total phytoplankton count during the study period. The least abundant phytoplankton in the reservoir is Dinophyceae it has a total number of 40 individual species which represent 3.57% of the total phytoplankton count during the study period. The result also indicated the mean percentage composition of chlorophyll-a (0.33 mg/L) in dry and (1.09 mg/L) in the wet season, chlorophyll-b (0.30 mg/L) in dry and (0.56 mg/L) in the wet season, and total chlorophyll (0.66 mg/L) in dry and (1.65 mg/L) wet season and in all the three sampling stations. Analysis of variance revealed there was a significant difference in chlorophyll between seasons (P > 0.05). More studies should be carried out to identify the plankton composition using advanced techniques such as Polymerase Chain Reaction (PCR).
Key Keywords: Dynamics, Diversity, Phytoplankton, Chlorophyll contents, and Ajiwa reservoir.