Measuring the Trajectory of Biological Uplift in Space and Time
Mark Southerland, PhD
Tetra Tech
Owings Mills, MD
The history of biological response to stream restoration includes some notable successes but many instances of little or no improvement in the resident biological communities. While failure of restoration designs to include adequate habitat and continuing, unresolved water quality problems are often invoked as reasons why biological uplift has not occurred, relatively little attention has been paid to the time lags involved and the importance of source populations for restorations to succeed. I will start by summarizing results from Maryland showing the quandary of poor biological uplift and then describing the factors most likely limiting uplift. The bulk of the talk will present results from two recent studies for the Chesapeake Bay Trust Restoration Research program that indicate the importance of allowing time for restorations to mature and locating restorations close enough to source populations for recolonization. In addition, I will describe how Regenerative Stream Conveyances (RSCs) can achieve physical habitat improvements, but do not attain dissolved oxygen and conductivity levels found in reference streams. Overall, the trajectory of fish and herpetofauna communities in RSCs, increase in abundance over time but do not attain the diversity of reference sites. Benthic macroinvertebrate communities at stream restorations show a small, but significant effect of the distance to healthy streams, an effect that is most pronounced with increasing years post-construction. Lessons for restoration success include tempering expectations for uplift, especially in urban areas, while incorporating good streams as “stepping stones” to facilitate dispersal. Lessons for monitoring include sampling multiple communities that may respond differently and including pre-restoration monitoring to detect uplift that may not approach reference conditions.
About Mark Southerland, PhD
Mark Southerland, Ph.D., is ninja-ecologist at Tetra Tech and was primary author of the EPA national program guidance on biological criteria, lead consultant on the MBSS for Maryland DNR, and consultant to MDE on impaired waters, stressor identification, and TMDL programs. He has helped 18 counties and cities in Maryland, Virginia, Delaware, and South Carolina develop stormwater programs and comply with the Chesapeake Bay and local TMDLs. Mark has chaired or served on the boards of Maryland Water Monitoring Council, Science Council of the Maryland Academy of Sciences, Patapsco Heritage Greenway, Howard County Environmental Sustainability, Howard County Conservancy, and Safe Skies Maryland.