The impact of applying rice straw substrates on periphyton and plankton abundance and community composition

An experiment had been accomplished over a fish culture season which extended from May to December; to investigate the abundance, dynamics and community composition of both phyto and zoo plankton. Six earthen ponds each of 1000 m² volume and 1 m in depth were divided into two groups; the 1^st one implemented as control (T₁), while dry rice straw introduced to the ponds of the 2^nd group (T₂) in the rate of 45 g/m². All ponds were fertilized with chicken manure in the rate of 15 kg/pond/week. All ponds received mono sex Nile tilapia fry in the rate of 3 fry/m².Abundance, dynamics and community composition of both phyto and zooplankton were monthly detected. Obtained results revealed that the highest total phytoplankton count was during August, and that count in source water was lower than that in T₁ and T₂ treatments. The highest total zooplankton count in source water was at the beginning of the experiment during May, while the 1^st achieved peaks of total zooplankton count in source water as well as in the two investigated treatments; were during August. Total zooplankton count in source water was higher than that in T₁ or T₂ treatments. Concerning phytoplankton community composition; Cyanophyta dominated other groups in source water, T₁ or in T₂ treatment, while with respect to periphyton community composition; Chlorophyta dominated other groups on rice straw mats, while copepods dominated the other zooplankton groups in source water and in the two investigated treatments. It's concluded that different management techniques, such as fertilization, type of cultivated species and applying substrates for periphyton growth, influenced the community composition of phyto and zooplankton as well as periphyton organisms.