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| Content Provider | Springer Nature Link |
|---|---|
| Author | McGowan, Suzanne Leavitt, Peter R. Hall, Roland I. |
| Copyright Year | 2005 |
| Abstract | Lake-level fluctuations are common in the North American Great Plains region, where large-scale climate systems (El Niño, the Pacific Decadal Oscillation) and periodic droughts cause substantial hydrologic variability in both summer and winter. To date, most such research has focused on the effects of summer droughts on prairie lake ecosystems; therefore, we studied the impact of water-level decline during winter on ecosystem structure and function. Specifically, we hypothesized that lower lake levels during winter would increase anoxia, freezing and scouring of benthos, fish kills, herbivory by zooplankton, and nutrient release from sediments. In addition, we tested the hypothesis that winter droughts may initiate a switch between alternative stable states (turbid, clear). Physical, chemical, and biological variables were monitored from 1996 to 2001 in both Wascana Lake, which experienced a 50% decline in lake level, and Buffalo Pound Lake, where water levels were constant. A combination of before-after-control-impact (BACI) and multivariate analyses showed that drawdown resulted in elevated NH4-N concentrations following reinundation; otherwise there were few detectable effects on lake water chemistry (PO4-P, NO3-N, total dissolved nitrogen, total dissolved carbon) or pelagic food web structure (phytoplankton, zooplankton), and the experimental lake remained in a macrophyte-rich state. There was, however, a 2.5-fold increase in macrophyte abundance and a shift from a community dominated by Ceratophyllum demersum before drawdown to one composed of Potamogeton pectinatus after manipulation. Overall, the lack of substantial dewatering effects suggests that lakes of the northern Great Plains may be resilient to severe winter conditions, possibly because of the recruitment of fish from regional metapopulations during summer. Further, our results indicate that lower water levels during winter likely promote the buffer mechanisms that reinforce a macrophyte-rich, clear-water state in shallow prairie lakes. |
| Starting Page | 694 |
| Ending Page | 708 |
| Page Count | 15 |
| File Format | |
| ISSN | 14329840 |
| Journal | Ecosystems |
| Volume Number | 8 |
| Issue Number | 6 |
| e-ISSN | 14350629 |
| Language | English |
| Publisher | Springer-Verlag |
| Publisher Date | 2005-09-09 |
| Publisher Place | New York |
| Access Restriction | One Nation One Subscription (ONOS) |
| Subject Keyword | alternative stable states Before-after-control impact (BACI) analysis droughts lake drawdown macrophytes phytoplankton pigments prairie lakes shallow lakes whole-ecosystem experiment zooplankton Ecology Plant Sciences Zoology Environmental Management Geoecology/Natural Processes Nature Conservation |
| Content Type | Text |
| Resource Type | Article |
| Subject | Ecology Environmental Chemistry Ecology, Evolution, Behavior and Systematics |
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