Thursday, May 29, 2008 - 9:30 AM
523

Nutrient and bacterial dynamics of aquatic floodplain habitats in a southeastern u.s. blackwater river-floodplain ecosystem

Nancy K. Weibell, Department of Biological Sciences, University of Alabama, 3106 Love Point Rd., Stevensville, MD 21666 and Amelia K. Ward, Department of Biological Sciences, The University of Alabama, Box 870206, Tuscaloosa, AL 35487-0206.

Many low gradient rivers, if unregulated, periodically inundate floodplains, replenishing sloughs and pools.  Such aquatic floodplain habitats, depending on their proximity to the main channel, may experience drastic changes in physical and biological variables during different seasons and hydrological phases.  We monitored water chemistry, bacterial abundance, and bacterial productivity for over a year in the main channel and floodplain of the Sipsey River on the Coastal Plain of the southeastern U.S.  Season, flooding frequency, and proximity to the main channel all influenced water chemistry and bacterial dynamics.  Average dissolved oxygen and NO3-N (DO 7.29 mg/L, NO3-N 78 μg/L) were both significantly higher in the main channel than the floodplain (DO 5.03 mg/L, NO3-N 37 μg/L), while average dissolved organic carbon, nitrate, and bacterial productivity were higher on the floodplain (DOC 8.83 mgC/L, DON 288 μgN/L, BCP 4.31 x 10-6 gC/L/H) than the main channel (DOC 7.47 mgC/L, DON 243 μgN/L, BCP 2.94 x 10-6 gC/L/H).  Hydrological disconnection compounded with warm water temperature caused greater differences between main channel and floodplain habitats in summer.  Periodic flooding replenished water in aquatic floodplain habitats and facilitated nutrient exchange between the main channel and floodplain.


Web Page: floodplain, nutrients, bacteria

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