Influence of <i>Clarias gariepinus</i> (Teugels) cage cultures on water quality, phytoplankton and periphyton composition: a case study of Ahmadu bello university reservoir, Nigeria

Abstract

Water quality, periphyton and phytoplankton growing as a function Clarias gariepinus (Burchell, 1822) cage cultures have rarely been investigated. Physical and chemical factors associated with cage culture of Clarias gariepinus in relation to phytoplankton and periphyton were examined fortnightly from May to June 2009 in the Ahmadu Bello University reservoir. Phytoplankton abundance based on divisions showed that Chlorophyta > Bacillariophyta > Cyanophyta, while for periphyton Chlorophyta > Euglenophyta > Cyanophyta > Bacillariophyta. Community structure analyses showed that species diversity was highest in the cages, while species dominance was highest on the bamboo raft periphyton community. Phytoplankton and periphyton distribution and abundance was closely related to the physicochemical characteristics of the water especially nitrate and phosphate concentrations. The physicochemical parameters were within acceptable limits for fisheries, and algal composition posed no risk to the cultivated fish and the reservoir.

Keywords: physicochemical parameters, microalgae, cyanobacteria, aquaculture, artificial substrates