2 Plenary 10:30

Abstract: Closing Plenary Session  10:30 am (BACK)

The Effectiveness of Multiple-Scale Spatial and Temporal Monitoring for Assessing Condition in Degraded and Restored Streams

Paul Mayer
EPA’s National Health and Environmental Effects Research Lab

Streams are dynamic systems especially difficult to monitor because biotic and chemical processes occur at multiple spatial and temporal scales.  Furthermore, streams consist of surface water and groundwater components that interact in important ways that drive these critical processes.  Characterizing groundwater-surface water interaction is difficult because of physical obstacles to sampling.  We present results from multi-scale spatial and temporal monitoring that revealed geochemical and biochemical patterns important in watersheds and critical to the recovery of restored streams.

We employed surface water sampling methods including high frequency grab sampling (sampling slam), real-time data logging, regular (weekly, monthly) sampling, and use of conservative, reactive, dye, and isotopic tracer methods.  We employed groundwater sampling methods including shallow piezometers, deep wells, isotope injection tracers (push/pull), and use of temperature as a flow tracer.  We also employed lab assays to identify microbial activity, abundance, and genetic diversity associated with biochemical processes.  We placed our bieogeochemical data in a spatial construct using LIDAR data and spatially explicit statistical models designed to estimate values beyond our sampling points.

No one spatial or temporal sampling approach alone adequately revealed the complexity of biogeochemical processes in streams or watersheds.  Both short-term and long-term data sets are needed to characterize temporal variability in stream ecosystems and both fine-, watershed-, and regional-scale data are required to adequately characterize spatial variability.  Monitoring is especially challenging in urban ecosystems where hydrology has been severely altered.  Assessment of the recovery of restored streams will require robust sampling designs that evaluate conditions before and after restoration efforts and/or involve the use of reference sites.  A fundamental understanding of the history of sites, including legacy effects of past land use and nutrient loads based on geological studies and paleobiology, will be essential to identify feasible recovery goals and objectives.