Phytoplankton Diversity and Abundance in Challawa Industrial Creek, Kano State

Industrial effluents discharged into Challawa Creek in Kano State, North West Nigeria, have altered aquatic ecosystem quality, yet phytoplankton community dynamics in this impacted waterway remain largely undocumented. This study assessed phytoplankton diversity and abundance in Challawa Industrial Creek across three sampling stations representing upstream, mid-stream, and downstream positions relative to industrial discharge points. Monthly samples were collected over six months spanning both seasons. Phytoplankton identification and cell density counts were performed using a haemocytometer and phase contrast microscopy. Water quality parameters, including pH, dissolved oxygen, conductivity, nitrate, and phosphate, were measured in situ and in the laboratory. A total of 64 phytoplankton taxa from 6 divisions were identified. Chlorophyta was the most species-rich division (28 taxa), followed by Bacillariophyta (18 taxa) and Cyanobacteria (11 taxa). Species richness and Shannon-Wiener diversity declined significantly from the upstream station (H' = 3.12) to the downstream station (H' = 1.84), mirroring increasing industrial effluent loading. Cyanobacteria blooms dominated the downstream station, indicating eutrophic conditions. Dissolved oxygen and species diversity showed a significant positive correlation (r = 0.78, p < 0.05). The study concludes that Challawa Creek is experiencing progressive phytoplankton community degradation driven by industrial pollution, and recommends immediate effluent treatment enforcement by the Kano State Environmental Protection Agency, alongside regular biomonitoring programmes using phytoplankton as bioindicators. Keywords: phytoplankton, diversity, Challawa Creek, industrial effluent, biomonitoring