Past Abstract Details


2009 talk

Effects of Simulated Flood Disturbances on Didymosphenia Geminata

Ianniello, Richard S 1

1 University of Colorado

In order to assess the resilience of the nuisance diatom didymosphenia geminata in 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 didymo cells. Microscopic cell counts compared to ash free dry mass data showed that the diatom cells of didymosphenia geminata are less resilient and more prone to removal by disturbances than the polysaccharide stalk material that the cells create. This indicates that the didymosphenia cells can be removed from the stalk material without removal of the stalk material itself. The possibility that didymosphenia developed in a setting with higher velocity would create more resilience was also examined although the collected data failed to provide conclusive results.

Kumar S., Spaulding S., Stohlgren T., Hermann K., tSchmidt T., Bahls L., 2008 Potential habitat distribution for the freshwater diatom Didymosphenia geminata in the continental US.Frontiers in Ecology and the Environment.

Spaulding, S.A., 2005. A nuisance diatom species: Didymosphenia geminata in western streams. EPA Science Forum.


Fig 1. Comparison of the rate of diatom cell loss to the rate of extracellular stalk material loss at 5 sites.





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