Effect Of Pond Type On Physicochemical Parameters, Phytoplankton Diversity And Primary Production In Kisii County, Kenya

Abstract

A study was conducted to establish the effect of pond type on physicochemical parameters, phytoplankton diversity and primary production in three different types of fish ponds namely; liner, earthen and concrete at Kegati Aquaculture Research Centre, Kisii, Kenya. A total of six fish ponds (104 m2) of three different types were randomly selected. Parameters investigated included physicochemical, nutrients, chlorophyll a and primary production. The study was conducted from the month of June 2015 to the month of November 2015. Phytoplankton diversity index was calculated by Shannon Wiener diversity index and phytoplankton richness calculated by Simpson richness Index. Statistical significance was set at p < 0.05. Statistical analysis was performed using Minitab version 17 Inc. for windows. There was a significant difference in chlorophyll a, temperature, dissolved oxygen, conductivity, pH and Secchi depth in the three ponds (ANOVA; p<0.05). There was no significant difference in nutrients measured in the three types of ponds (ANOVA; P˃0.05). In liner ponds Chlorogloea mierostoldes species was dominant while Anabaena flos-aquae were dominant in earthen pond while Microcystis aeruginosa was dominant in concrete pond. Liner pond had higher Shannon Wiener index 3.418, earthen pond 3.0439 and concrete pond 1.6414. Phytoplankton had a positive correlation with both gross and net primary production. Liner pond had higher levels of both chlorophyll a and amounts of both gross and net primary production as compared to measurements recorded from earthen and concrete ponds. In general liner pond showed a higher diversity of phytoplankton and high levels of primary production. The use of liner fish ponds in fish culture is recommended to realize increased production as they offer a favorable environment for phytoplankton growth and primary production.