SEASONAL DYNAMICS OF PLANKTON DIVERSITY AND PHYSICOCHEMICAL PARAMETERS IN THE GREAT KWA RIVER, NIGERIA

Abstract

The Great Kwa River supports diverse aquatic life and local livelihoods. However, variations in water quality and plankton

diversity due to seasonal changes remain underexplored. This study aimed to assess the physicochemical parameters and

their influence on plankton diversity and abundance, with a focus on seasonal and monthly variations. Standard analytical

methods were used to measure parameters such as pH, temperature, DO, biological oxygen demand (BOD), nitrates, and

phosphates, alongside plankton identification and enumeration. Results showed significant seasonal differences,

including higher pH (7.33 ± 0.05) and lower nitrate levels (3.93 ± 0.18 mg/L) in the dry season compared to the wet season.

Plankton diversity indices were significantly higher in the wet season, with phytoplankton diversity reaching 2.46 ± 0.03

and zooplankton diversity at 2.11 ± 0.03. Correlation analysis revealed strong positive relationships between nitrate and

plankton abundance (r = 0.802–0.873, p < 0.05), and negative correlations between BOD and plankton diversity indices (r

= -0.816 to -0.864, p < 0.05). The study concludes that seasonal nutrient fluctuations significantly impact plankton

diversity and abundance, with implications for ecosystem health. To safeguard this riverine ecosystem, the study

recommends implementing nutrient management strategies to mitigate pollution, particularly during peak runoff periods