Abstract

Nutrients availabilty is one of the major contributors to distribution and growth of phytoplankton species. Physicochemical properties and phytoplankton species and their distribution in Shagari Reservoir were evaluated. Standard methods of UNEP were used to determine monthly physicochemical flux properties, diversity and distribution of phytoplankton species were also determined. Phytoplankton classes identified included Bacillariophyceae, Chlorophyceae, Cynophyceae and Dinophyceae. Class Chlorophyceae had the highest annual percentage distribution (37.55%) with four species identified. The least monthly percentage (7.64%) was recorded in November by Dinophyceae. Anabaena wisconsineae (Dinophyceae) had the highest frequency of occurence (96.6%). August, September and October were the most turbid months using Secchi disc measurement with 8.30, 9.0 and 9.8cm respectively. The monthly variation in the physicochemical parameters may be due to seasonal changes and human activities. The levels of nitrogen and phosphorus ranged from 0.30-7.30 Mg/l and 0.1-0.8Mg/l respectively. The reservoir has low species of phytoplankton, which may be due to low levels of nutrients and age of the reservoir.

Key words: Phytoplankton, Physicochemical, Reservoir, Chlorophyceae, Shagari, Sokoto, Nigeria