This project takes place at Timberlake, which is being researched through a collaboration between my advisor, Dr. Martin Doyle, and Dr. Emily Bernhardt’s group at Duke. I have another page with more detail on the site in general.
In this study, the Duke folks decided to initiate a water level drawdown to return the site to the water level it experienced pre-restoration (when it was used for agriculture). Due to some unique site geomorphology, dewatering established a “drought gradient” in the main channel at the site. I took advantage of this gradient to track macroinvertebrate community response to dewatering, both over time and over conditions of increasing severity. I also continued to sample after full flow conditions were restored.
This research was a part of my master’s thesis at UNC and has recently been published in a special issue of Hydrology and Earth System Sciences (you can also view the paper on my pubs page).
In brief, dewatering did not influence community structure in terms of richness, but it did knock down abundance of certain taxa (especially those associated with near-bank vegetation), while re-wetting allowed open-water predator species to come back in force. Interestingly, this community change was not apparent as a change in the community mean, but rather as an increase in community dispersion. More severely-impacted sites had greater dispersions over the course of the study, in other words, but all sites had more or less the same community mean. I thought this was pretty darn cool.
Furthermore, we had expected rewetting, which was basically a short-term flood, to be another disturbance immediately after the drawdown. Thus, we thought the bugs would respond even more negatively to rewetting. Instead, they came back with a vengeance in most cases. This was pretty cool to me too.