Assessment of Zooplankton Diversity and Its Relationship to Water Quality in the Tiga Dam, Kano State

The Tiga Dam in Kano State, North West Nigeria, supports both a commercial fishery and supplies irrigation water to agricultural lands in the Kano River Irrigation Project, yet ecological data on zooplankton communities in this reservoir are limited. This study assesses zooplankton species diversity, abundance, and its relationship with selected water quality parameters in the Tiga Dam during the dry and wet seasons. Samples were collected monthly from three stations using a 65-micron plankton net towed horizontally for a fixed distance. Water quality parameters, including temperature, pH, dissolved oxygen, turbidity, total dissolved solids, nitrate, and phosphate, were measured simultaneously. Zooplankton were enumerated and identified to genus level using standard taxonomic keys. A total of 38 zooplankton taxa were identified, with Rotifera, Copepoda, and Cladocera as the dominant groups. Zooplankton abundance was highest during the late dry season, corresponding with elevated phosphate concentrations and reduced water transparency. Species richness was higher at the station with least agricultural runoff influence. Shannon-Wiener diversity index values ranged from 1.74 to 2.91, indicating moderate diversity. Canonical correspondence analysis revealed that phosphate, dissolved oxygen, and turbidity were the most significant predictors of zooplankton community structure. The study contributes baseline ecological data for the Tiga Dam and highlights the potential impact of agricultural nutrient runoff on zooplankton community composition, with implications for fish production in this strategically important reservoir.

Keywords: zooplankton diversity, water quality, Tiga Dam, canonical correspondence analysis, Kano State