The ecological response of shallow oxbow lakes to variability in hydrology and catchment development in large river floodplain ecosystems (RFE) in Arkansas remains largely unknown. Investigating these responses will advance our understanding of ecological evolution of oxbow lakes in response to the major environmental drivers, which will establish baseline conditions required to develop effective management practices for RFE. In this pilot study, we examined the potential of using a dated surface sediment core from Adams Bayou, a floodplain lake located within the Cache-Lower White River Ramsar site in SE Arkansas. Stratigraphic records of diatoms and sediment geochemistry were used to ascertain variation in Adams Bayou's ecological condition. During 1968–2008, in response to hydrological and anthropogenic changes, Adams Bayou's diatom assemblages progressed from predominantly benthic (Gomphonema parvulum and Meridion circulare) to primarily planktonic assemblage (Aulacoseira granulata and Cyclotella meneghiniana), along with a decrease in magnetic susceptibility (k) and % silt. Statistical analyses reveled that during 1968–2000, higher hydrological connectivity and catchment alterations drove Adams Bayou's ecosystem. After 2000, lower hydrological connectivity and increase in cultivation were the major drivers. The potential impact of increasing air temperature was also noted. The shift in Adams Bayou from a connected, clear, mesotrophic state to a relatively isolated, turbid and nutrient enriched state is consistent with regime shift models and highlights its sensitivity to a combination of environmental stresses prevalent in the catchment. Although fluvial systems pose challenges in establishing clear chronologies, oxbow lake sediments can be a effective paleoecological archives. Our work provides clear evidence for the change in the ecological character of this wetland of international significance and flags the need for a wider assessment of water bodies across this site under obligations to the Ramsar Convention.
|Original language||English (US)|
|Number of pages||11|
|Journal||Science of the Total Environment|
|State||Published - 2016|
Bibliographical noteFunding Information:
This study would not have been possible without the financial support by DEB NSF-0836131 (awarded to Sonja Hausmann, Stephen K. Boss and Ruchi Bhattacharya). We are also thankful for funding provided by the Geological Society of America graduate student research grant, graduate assistantship in the Environmental Dynamics program, and Doctoral Academy Fellowship from the University of Arkansas Graduate School to Ruchi Bhattacharya.
© 2016 Elsevier B.V.
Copyright 2018 Elsevier B.V., All rights reserved.
- Catchment alteration
- Hydrological connectivity
- Regime shift
- River-floodplain ecosystem
- Water quality
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