PHYSICAL PROCESSES AFFECTING THE DISTRIBUTION OF DYDYMOSPHENIA GEMINATA BIOMASS BLOOMS IN RAPID CREEK, SOUTH DAKOTA

Didymosphenia geminata is a freshwater diatom that has invaded and colonized many of the world’s oligotrophic streams and rivers, including Rapid Creek in Western South Dakota - a perennial oligotrophic stream that emerges from the Black Hills and is fed by cold water release from the Pactola Reservoir. Since 2002, D. geminata blooms have been observed in certain stretches of the Rapid Creek. We measured flow rates, depth, temperature, stream bed characteristics, water chemistry and D. geminata biomass in regions with and without blooms. The presentation will discuss how changes in physical parameters along the various reaches of the Creek impact the biomass distribution of this invasive alga.