Ianniello, Richard S听1
1听University of Colorado
In order to assess the resilience of the nuisance diatom听didymosphenia geminatain relation to flood disturbances, a simulation technique was developed to measure the loss of algal material due to flooding over a period of time. The diatom is of interest due to its recent unexplained expansion of habitat, invasive capabilities and ability to form extracellular polysaccharide stalk material over the substrate of a stream that can cause substantial ecological damage. The simulation was done by placing rocks affected with didymo into a cylindrical container with water and turning the container to simulate bed movement during a flood. Rock samples were taken from Boulder Creek in Colorado, and processed with the simulation to provide water samples that were then analyzed for biomass, chlorophyll-a and number of听didymo听cells. Microscopic cell counts compared to ash free dry mass data showed that the diatom cells of听didymosphenia geminata听are less resilient and more prone to removal by disturbances than the polysaccharide stalk material that the cells create. This indicates that the听didymosphenia听cells can be removed from the stalk material without removal of the stalk material itself. The possibility that听didymosphenia听developed in a setting with higher velocity would create more resilience was also examined although the collected data failed to provide conclusive results.
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