Survey of Aquatic Macrophytes and Their Ecological Roles in Tiga Dam, Kano State

Aquatic macrophytes are integral components of freshwater ecosystems, providing habitat structure, oxygen production, and nutrient cycling functions, yet their diversity and ecological roles in Tiga Dam, Kano State's largest water reservoir, remain undocumented. This study surveyed aquatic macrophyte species composition and assessed their ecological roles in Tiga Dam across four sampling zones representing inlet, central, shoreline, and outlet areas. Sampling was conducted during dry and wet seasons using belt transects along the shoreline and underwater observation for submersed species. Voucher specimens were identified at Bayero University Kano Herbarium. Water quality parameters relevant to macrophyte growth were measured at each zone. Twenty-six aquatic macrophyte species from 17 families were documented. Nymphaea lotus, Ceratophyllum demersum, and Pistia stratiotes were the most abundant. Emergent macrophytes dominated the inlet and shoreline zones, while submerged species were more common in the central zone. Species richness was significantly higher during the wet season (23 species) than the dry season (18 species). Macrophyte biomass density showed a significant positive correlation with total phosphorus (r = 0.71) and negative correlation with water transparency (r = -0.64). Macrophytes were assessed to contribute materially to nutrient retention and fish nursery habitat provision. Pistia stratiotes was recorded as a problematic invasive at the inlet zone. The study recommends macrophyte monitoring as part of Tiga Dam's water resource management framework.

Keywords: aquatic macrophytes, Tiga Dam, species diversity, ecological roles, Kano State