Macroinvertebrate community responses to an experimental drought gradient on the outer coastal plain of North Carolina

The effects of drought on aquatic macroinvertebrate communities are often difficult to assess due to the highly stochastic, unpredictable nature of such events.  In addition, most drought studies have emphasized the interplay between stream geomorphology (e.g. presence of physical refugia) and hydrology (e.g. depth) in determining macroinvertebrate community responses to drought; however, these habitat components are often difficult to decouple.  In this presentation, we will discuss the effects of an experimental drought and rewetting at the Timberlake mitigation site on the North Carolina Outer Coastal Plain.  This drought was initiated by turning on a relic water pumping system that historically drained the site for agriculture prior to its restoration back to a wetland/riverine system.  The planned nature of this water abstraction allowed macroinvertebrate sampling to occur at multiple intervals before and during the water drawdown and after rewetting.  In addition, the unique topography of the site allowed a hydrologic gradient of drought conditions to be established, all with homogenous substrate and bank conditions.  Thus, the study design allowed us to consider drought effects due to hydrologic change in the absence of confounding, refugia-related geomorphology.  The effects of this drawdown and subsequent rewetting on the macroinvertebrate community will be discussed.