Assessment of primary productivity, nutrient levels and trophic status of kuinet dam, kenya

Abstract

This study was carried out in Kuinet (Chepkongi) Dam within Uasin-Gishu County, Kenya to assess primary productivity, nutrient levels and trophic status of the dam. Water samples were collected at four sampling stations (inflow, outflow and in the middle) of the dam monthly from November 2014 to January 2015. The samples were used to assess the chloropyhll-a, net primary productivity and the main physico-chemical variables. Phytoplankton was sampled using a phytoplankton net, identified and counted using an inverted electronic microscope. Canonical Correspondences Analyses was carried on to ascertain the correspondence relationships of the sampled parameters. The trophic status was calculated using the Carlson method considering the parameters: chloropyhll-a, Secchi Depth and Total Phosphorus. The phytoplankton community of Kuinet Dam is composed mainly of four families; Bacillariophyceae and Chlorophyceae families each had 11 species followed by Cyanophyceae with 5 species and Desmidiaceae with 3 species. The family Chlorophyceae dominated in abundance in all months. Net primary productivity ranged from 0.182±0.09 mgO2L-1d- 1 in December to 0.299±0.13 mgO2L-1d-1 in November. Dissolved Oxygen, net primary productivity, Biological Oxygen Demand and temperature displayed similar trends during the three sampling months. Chlorophyceae had near correspondence with these three parameters than the others according to CCA. The trophic status of the Dam resulted both mesotrophic and eutrophic. From the study, we reject the HO hence the primary productivity of Kuinet dam favors aquaculture during the dry spell period. This in turn aids in facilitating the achievement of attaining the estimated potential production level of 2000 tons according the Uasin Gishu district environment action plan 2009-2013.