Species Diversity of Net Zooplankton and Physiochemical Conditions in Keystone Reservoir, Oklahoma

Abstract

Net zooplankton collections and physiochemical measurements were made monthly in four stations each in the Cimarron River and Arkansas River arms and one station at the dam of Keystone Reservoir, Oklahoma, from June 21, 1967, to June 24, 1968. Conductivity was considerably greater in the Cimarron Arm than in the Arkansas arm or the dam, while turbidity, alkalinity, and zooplankton density were generally higher in the Arkansas arm. Variation among stations in temperature and dissolved oxygen was slight. A total of 44 taxa of zooplankton were collected. Shannon's formula was used to evaluate species diversity (d) of zooplankton. Variance values of d indicated only a slight gain in precision by increasing the sample size to above 400 individuals. Mean annual species diversity was slightly lower in the Cimarron Arm than in the Arkansas Arm. Diversity values decreased slightly through early winter and decreased abruptly and reached minimum values in late winter and early spring. Coefficients of correlation between physiochemical parameters and species diversity unadjusted for month and station effect were compared with adjusted coefficients.