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Monday, June 4, 2007 - 3:15 PM
55
Structural and Successional Characteristics in Artificial Stream Biofilms in Response to Flow Regime as Seen Through a Confocal Microscope
Chad A. Larson and Sophia I. Passy. Biology, The University of Texas at Arlington, 501 S. Nedderman, 337 Life Science, Arlington, TX 76010-0498
In lotic ecosystems, the structural and successional characteristics of the periphytic communities are greatly influenced by current velocity. However, it is still poorly known how current shapes the three-dimensional structure of the biofilm and its patch mosaic. In recirculating artificial stream flumes, we subjected periphytic communities accumulating on ceramic tiles to different water velocity regimes (10 and 30 cm · sec-1) and examined them with confocal and light microscopy. Biofilm spatial properties, such as average patch heterogeneity and fractal dimension differed between the two flow regimes (p ≤ 0.05) at each sampling period, with lower velocity streams showing higher heterogeneity and fractal dimensions of periphytic communities than higher velocity streams. Depth profiles of the accumulating periphytic communities at various times throughout the experiment showed that the spatial distributions of major algal groups (green algae, diatoms, and cyanobacteria) responded to the different water velocities. By the end of the experiment (35 days), periphytic communities in high velocity streams were dominated by diatoms, while more diverse periphytic communities developed in low velocity streams. To our knowledge, this represents the first study to employ these novel techniques for examining in such depth and detail, the succession and three-dimensional structure of periphytic communities.