Abstract
It has been suggested that reconnection of the lower and upper portions of the Cache River will have ecological benefits. To assess potential responses and guide reconnection efforts, we have developed models predicting the ecological responses of potential increases in flow in the lower Cache River. Preliminary data suggest that duckweed cover, which is associated with lack of flow, is an important factor governing oxygen availability in the stream. We predict that small increases in discharge will reduce duckweed cover and result in exponential increases in dissolved oxygen. We also hypothesize that increases in discharge will alter macroinvertebrate communities. In particular, increased flow will shift macroinvertebrate community composition from dominance by collector-gatherers to filter-feeders such as hydropsychid caddisflies and black flies. Our model also suggests that macroinvertebrate production on snag habitats may increase up to 10% due to the increased contribution of filter-feeders. Collectively, our analyses suggest that reconnection may have tangible, positive impacts on physical and biological components of the lower Cache River.
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Heidi Rantala received her PhD in Biological Sciences with Alex Huryn at The University of Alabama in 2009. Her dissertation research focused on secondary production, leaf litter breakdown, and macroinvertebrate community structure in Arctic tundra streams across a glacial chronosequence. She completed an M.S. in Water Resources Science at The University of Minnesota and B.S. degrees in Biology and Geology from The University of Wisconsin-Eau Claire. Heidi’s interests include the ecology of stream macroinvertebrates, landscape ecology, stream restoration, and paleolimnology. She is especially interested in the biology of aquatic flies and their role in ecosystem processes. She is also interested in role of lakes on stream community structure and ecosystem processes. She is currently a post-doctoral fellow at SIUC working with Matt Whiles, in Zoology, and Greg Wilkerson in Civil and Environmental Engineering. They are working on a project in the Cache River watershed, predicting the ecological benefits of a proposed reconnection of the lower part of the Cache River to its headwaters.