COMPARATIVE-ANALYSIS OF VARIABLES TO MEASURE RECOVERY RATES IN STREAMS

We assessed a series of chemical and biological variables for their ab ilities and cost effectiveness in determining recovery rates in stream s. Using data gathered at the experimental streams of the Monticello E cological Research Station, several water-quality variables (DO, pH. n utrients), macroinvertebrate densities, macrophyte biomass, and periph yton biomass, and several ecosystem-level variables (e.g., primary pro duction) were compiled and analyzed. Water-quality variables were rela tively inexpensive to measure, and many would be relatively easily col lected for assessing recovery rates; however, their overall explanator y power for determining recovery of streams, especially biological phe nomena, was limited. Several biological variables, including gross pri mary production, respiration, leaf litter decomposition rates, macroin vertebrate richness, and Collembola density, could be measured reasona bly well and required relatively small sample sizes (n < 10) for detec ting recovery rates. However, collection of most of these variables wa s more costly than collection of chemical water-quality variables. The ultimate determination of which variables to measure in assessing rec overy in a given ecosystem will need to be based on the disturbances b eing examined, the importance of the variables to stream health, and t he 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 u ltimately improving the quality of the environment.