A Study of the Phycoperiphyton Community in the Black River, La Crosse County, Wisconsin

Abstract

Phycoperiphyton taxonomic composition, numbers, biomass, and pigments were analyzed from materials gathered from the Black River, La Crosse County, Wisconsin. Phycoperiphyton samples were collected from two stations at each of four sites and water samples were also collected at each of the four sites during the open water season, April through November 1976. Floating samplers fitted with glass slides served as the phycoperiphyton substrate. Station selection was based on current velocity and direct sunlight. The following measurements were made at each side: temperature, dissolved oxygen, pH, alkalinity, calcium and total hardness, ortho-phosphorous, nitrate, and nitrite. River depth and current velocity were measured at each station. A total of 56 genera and 205 species (29 species were further identified to include 75 varieties) were found. The phycoperiphyton community was dominated greatly by members of the class Bacil1ariophyceae (ca. 98% of the total community). Achnanthes lanceolata, was the dominant species during spring months. Melosira varians dominated by mid-June and was succeeded by Cocconeis placentula euglypta during July through late September. Navicula cryptocephala dominated next in the autumn, and during the final sampling period in November Diatoma vulgare was the dominant species.