Miller, K. F. U.S. Geological Survey, kfmiller@usgs.gov
Waldron, M. C. U.S. Geological Survey, mwaldron@usgs.gov
Hooper, R. P. U.S. Geological Survey, rphooper@usgs.gov

 
BIOTIC CONTROL OF SUMMER DISSOLVED OXYGEN CONCENTRATIONS AND A POTENTIAL MEASURE OF PHYTOPLANKTON GROWTH RATES IN NAVIGATION POOLS OF THE UPPER OHIO RIVER, USA
 
Hourly measurements of water temperature, pH, and dissolved-oxygen (DO) concentration, made during four summers (June through October, 1992-1995) in two navigation pools on the upper Ohio River to assess the effects of hydropower generation on downstream river quality, were examined for temporal patterns relating DO concentration to changes in river discharge. During periods of reduced discharge (5 days or more at 560 cubic meters per second or less), monitored pH values and DO concentrations exhibited diel fluctuations characteristic of phytoplankton photosynthetic activity. Higher discharges arising from rainfall on the drainage basin eliminated the diel fluctuations, presumably by diluting and redistributing the phytoplankton in the pools. When discharge remained low for several weeks, the daily pH and DO maxima increased and decreased over periods of 16 to 22 days. These recurring periods were identified by power spectral analysis of the pH and DO time series and may represent cycles of growth and decline of the phytoplankton populations. The rate of increase in the daily maximum DO concentration during the first half of the cycle may provide an in situ measure of phytoplankton growth rate for use in calibrating models that simulate photosynthetic DO production in the pools.
 
Day: Tuesday, Feb. 2
Time: 11:15 - 11:30am
Location: Sweeney Center
 
Code: SS19TU1115S