PARASITOLOGICAL AND ECOLOGICAL ASSESSMENT OF SMALL WATER BODIES (SWBs) FOR PRODUCTION OF TILAPIA (Oreochromis niloticus L.) IN UASIN GISHU AND SIAYA COUNTIES, KENYA

Abstract

Sustainability of culture-based fisheries (CBF) development in small water bodies (SWBs) largely depends on their ecological conditions and productivity. Studies were conducted from November 2010 to July 2012 in Kesses and Kerita dams in Uasin Gishu and Mauna and Yenga dams in Siaya. Sampling for water quality, phytoplankton, macroinvertebrates and fish parasites was conducted once a month. Phytoplankton and macroinvertebrates were collected using plankton and scoop nets respectively. Water quality parameters were measured in-situ using electronic meters. Parasitological examination was done according to standard procedures. Significant differences in temperature (F=17.38; p=0.000), DO (F=8.76; p= 0.000) and TN (F= 6.34; p=0.01) were found between Uasin Gishu and Siaya dams. Water pH in Kesses was higher during the wet season (F=14.44; p= 0.000) while TN and TP were higher during the dry season (F=9.38; p=0.02) and F=5.02; p=0.023 respectively). Similarly in Kerita, pH was higher during the wet season (F=15.98; p=0.01) while TN and TP were high during the dry season (F=43.21; p=0.00 and F=20.03; p=0.003 respectively). In Siaya, DO was higher during the rainy season (F=6.60; p= 0.01). During the wet season, Bacillariophyceae was more abundant in Kerita dam (H=5.45; p=0.02) and Desmidiaceae (H=4.07; p=0.044) in Kesses dam. The relative abundance of Ephemeroptera (H=16.07; p=0.003) and Plecoptera (H= 16.07; p=0.000) was higher during the wet season in Kesses while Hemiptera (H= 16.07; p=0.000) and Pulmonata (H= 9.04; p=0.002) was high during the dry season. Diplostomum parasites were associated with high TP levels in Kesses (rs= 0.621; p=0.0001) and with temperature (rs= 0.63; p= 0.002) in Mauna. Parasites affected the condition factor depending on seasonality and sex of fish. In Kesses, the condition factor of fish infected with Tylodelphys during the dry season was found to be significantly higher than un-infected ones (F= 18.86; p=0.000). While it is evident that seasonality and geographical location based on altitude have an effect on some aspects of water quality, phytoplankton, macroinvertebrates and parasites of fish in these SWBs, they are considered suitable for fish production as they are rich in phytoplankton and macroinvertebrate communities which serve as food. Development of mitigation measures against habitat degradation and water quality deterioration combined with strong community support for sustainable culture-based fisheries in these SWBs are recommended. .