COMPARATIVE-ANALYSIS OF VARIABLES TO MEASURE RECOVERY RATES IN STREAMS

We assessed a series of chemical and biological variables for their abilities and cost effectiveness in determining recovery rates in streams. Using data gathered at the experimental streams of the Monticello Ecological Research Station, several water-quality variables (DO, pH. nutrients), macroinvertebrate densities, macrophyte biomass, and periphyton biomass, and several ecosystem-level variables (e.g., primary production) were compiled and analyzed. Water-quality variables were relatively inexpensive to measure, and many would be relatively easily collected for assessing recovery rates; however, their overall explanatory power for determining recovery of streams, especially biological phenomena, was limited. Several biological variables, including gross primary production, respiration, leaf litter decomposition rates, macroinvertebrate richness, and Collembola density, could be measured reasonably well and required relatively small sample sizes (n < 10) for detecting recovery rates. However, collection of most of these variables was more costly than collection of chemical water-quality variables. The ultimate determination of which variables to measure in assessing recovery in a given ecosystem will need to be based on the disturbances being examined, the importance of the variables to stream health, and the available monetary resources. Generally, comprehensive analyses of recovery rates for a variety of aquatic systems will greatly increase our ability to develop a framework for predicting recovery rates and ultimately improving the quality of the environment.