Distribution of chironomids in the littoral zone of Lake Texoma, Oklahoma and Texas

Abstract

Lake Texoma in southcentral Oklahoma was formed by the impoundment of the Washita and Red Rivers. The Red River is more highly saline than the Washita and creates a complex salinity gradient across the reservoir. Populations of chironomids were monitored with multiple-plate samplers in areas of high (34–113 mg l−1 Cl−), intermediate (35–60 mg l−1 Cl−) and low (4–27 mg l−1 Cl−) salinity during the spring and summer of 1978. Food availability, temperature, salinity and wind direction influenced the distribution of the 14 genera and at least 22 species of chironomids which colonized the multiple-plate samplers. Filter-feeders attained their highest densities in the river-arm stations where levels of particulate organic matter (POM) were high. Algal grazers attained their highest densities in the clear intermediate area where the plates of the samplers were covered with algal mats. Most of the genera believed to be feeding primarily on POM decreased in density as the temperature and density of Glyptotendipes sp. rose. Certain species were restricted to either the Red River arm or the Washita River arm and this is probably a reflection of different salinity tolerances.