Zooplankton Community Structure in a Wastewater Treatment Plant. A Case of Suneka Wastewater Treatment Plant, Kenya

Abstract

Water quality determines aquatic organisms’ community structure. As a result, selected planktons have been used as bioindicators of water quality. In the current study, we determined zooplankton community structure and diversity in Suneka wastewater treatment plant in addition to selected physical and chemical parameters of the wastewater. The zooplankton samples were collected in triplicate once every month from August to December, 2019 from seven sampling points at sub-surface level. Temperature, pH, electrical conductivity (EC), and dissolved oxygen (DO) were measured in situ using calibrated portable professional series (YS1) multiparameter meter model 35C at each sampling point. Nutrient analysis, wastewater samples were collected in triplicate using acid-washed bottles from the different sampling points and analyzed ex-situ using the spectrophotometric method for the determination of water and wastewater according to APHA, 2014. The results revealed the presence of 13 zooplankton species belong to three taxa: Cladocera, Rotifera, and Copepoda. In terms of abundance, Cladocera was the most dominant group, while Copepoda and Rotifera maintained lower and more stable populations across the sampling stations. Moreover, the study revealed there was spatial and temporal variation in zooplankton in terms of diversity and distribution. The variations in zooplankton diversity can be attributed to changes in physical and chemical parameters in addition to primary productivity in the respective sampling stations. The study findings form baseline information on the zooplankton assemblage for the Suneka wastewater treatment plant for future studies.