Back to Sept. 2002 workshop site
Title: Dissolved Oxygen Flux, Nutrients, and Community Productivity in Some Central Plains Streams: What We Know and What We Think We Know!
Presenter: Donald G. Huggins, Central Plains Center for BioAssessment, Kansas Biological Survey, University of Kansas, Lawrence, KS
Abstract: The Central Plains Center for BioAssessment is studying the relationships betweeen nutrients, primary production, and diel-dissolved oxygen flux in wadeable streams of the Western Corn Belt Plains Ecoregion.
Over the last three years, we have deployed Aqua 2002 dissolved oxygen and
temperature data loggers in a total of 36 study streams for time periods of
10 or more days during low-flow conditions. In situ measures of pH, conductivity,
and turbidity, as well as dissolved oxygen and temperature that were used a
QA checks against concurrent loggers values, were obtained at the start and
finish of each deployment period. In addition, a series of physical stream measures
(e.g. velocity, depth, width, discharge) and grab samples of stream water were
collected at these same times for laboratory analysis of nutrients and water-column
chlorophyll and phaeophytin a concentrations. Lastly, three to five replicated
periphyton samples were collected both at the beginning and end of each deployment
period to determine benthic chlorophyll and phaeophytin a levels. Plots of dissolved
oxygen (DO) concentrations versus time clearly show a high degree of daily and
weekly fluctuation in the DO curves. Statistically significant correlations
were found that suggested strong relationships between various DO variables
and in-stream nutrient concentrations and other stream variables (e.g., periphyton
and chlorophyll a) existed in these stream systems during low flows. Initial
findings indicate that relationships between in-stream nutrient concentrations,
algal biomass, and DO regimes can be quantified during low-flow periods, but
a number yet-to-be quantified stream factors control these relationships. Daily
and weekly estimates of gross primary production and community respiration calculated
from the DO and temperature data are being examined as possible indicators of
stream function as it relates to nutrient enrichment and other stream factors.