2022 Early Hearing Detection & Intervention Virtual Conference
March 13 - 15, 2022
6/05/2017 | 11:45 AM - 12:00 PM | RESPONSE OF A RESERVOIR ECOSYSTEM TO CHANGES IN WATERSHED AGRICULTURE OVER TWO DECADES: THE STOICHIOMETRY OF NUTRIENT INPUTS AND PHYTOPLANKTON NUTRIENT LIMITATION | 306B
RESPONSE OF A RESERVOIR ECOSYSTEM TO CHANGES IN WATERSHED AGRICULTURE OVER TWO DECADES: THE STOICHIOMETRY OF NUTRIENT INPUTS AND PHYTOPLANKTON NUTRIENT LIMITATION
We present 23 years of data on the response of eutrophic Acton Lake to changes in watershed agriculture. Over the first decade, the use of conservation tillage increased greatly in the watershed. This led to large decreases in suspended sediment (SS) and P concentrations in inflow streams, and decreased (discharge-adjusted) loads of SS and P to the lake. However, during the second decade, stream SS changed little and soluble P actually increased. In contrast, stream nitrate changed little over the first decade, but declined sharply in the second decade. In Acton Lake, phytoplankton biomass increased markedly over the first decade, despite decreased inputs of P from streams, probably because declining lake SS concentrations alleviated phytoplankton light-limitation, and because of increasing biomass, and hence nutrient excretion, of detritivorous fish. Over the second decade, phytoplankton biomass showed no temporal trend. However, phytoplankton N-limitation became more common, whereas P was usually limiting in the first decade. This shift may reflect declining stream N:P ratios and a greater importance of internal loading, which has relatively low N:P. Our long-term data reveal complex, temporal scale-dependent responses of stoichiometry to changing watershed agriculture.
- C28 Land-Water Interfaces
- C27 Landuse and Non-Point source Impacts
- S19 Elements and energy as fundamental currencies of nature: using ecological stoichiometry as a tool to advance the sustainability of freshwater ecosystems
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Presenters/Authors
Michael Vanni
(), Miami University, vannimj@miamioh.edu;
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William Renwick
(), Miami University, wrenwick@miamioh.edu;
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Thomas Fisher
(), Miami University, fishert4@miamioh.edu;
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Emily Morris
(), Miami University, morris55@miamioh.edu;
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