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Indicators of Phosphorus Deficiency in Lake Erie

Indicators of Phosphorus Deficiency in Lake Erie. Leigh Martin Dr. Darren Bade April 14, 2012. Pre- Dreissenid Invasion. Pre- Dreissenid Invasion. Post- Dreissenid Invasion. Hypothesis.

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Indicators of Phosphorus Deficiency in Lake Erie

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  1. Indicators of Phosphorus Deficiency in Lake Erie Leigh Martin Dr. Darren Bade April 14, 2012

  2. Pre-DreissenidInvasion

  3. Pre-Dreissenid Invasion Post-Dreissenid Invasion

  4. Hypothesis • Based on the Nearshore Phosphorus Shunt hypothesis, we expect to find greater instances of P deficiency at offshore sites compared to nearshore sites

  5. Experimental Design Cattaraugus Cr. Westfield Erie Ashtabula R. Sterling State Park Grand R. Turtle Creek Turtle Cr. Huron R. • 8 Transects in June and August 2011 • 2 Western Basin, 3 Central Basin, 3 Eastern Basin • Depths ranging nearshore to offshore – 2, 5, 10, and 20 meters

  6. Experimental Design • Phosphorus Turnover Time < 60 minutes is P deficient • Phosphorus Debt • Amount of P taken up in 24 hours relative to the amount of Chl a. >0.075 µmole P/µgram Chl a. is P deficient

  7. Phosphorus Turnover – Western Basin Sterling State Park Turtle Creek 1489.6 1327.8 June No Deficiency Deficiency Turnover Time (min) August Depth (m)

  8. Phosphorus Turnover – Central Basin Grand River Ashtabula River Huron River June 13970.5 21055.4 Turnover Time (min) August 1121.4 Depth (m)

  9. Phosphorus Turnover – Eastern Basin June Erie, PA Westfield, NY Cattaraugus Creek 2084.4 Turnover Time (min) August 264.5 362.5 Depth (m)

  10. Chl. a Trends Chl. a • Seasonal increases from June to August in all basins • Lower Chl. a levels at offshore depths Average Chl a Values

  11. SRP Trends • Average SRP showed a seasonal decline in Western and Central basins • Higher SRP values were found more often at nearshore sites than at offshore sites Average June SRP Average August SRP

  12. Summary & Conclusions • Seasonal versus Spatial P Limitation • Seasonal declines in SRP = Increased P deficiency overall • Spatially, there was no clear trend of increasing P deficiency from nearshore to offshore • Declines in offshore Chl. a may not be due to declines in SRP • Potential Limitation by N or Co-Limitation by N and P in offshore areas

  13. Acknowledgments Kent State University Curtis Clevinger Heather Kirkpatrick Smith ShunyaYagi Dr. Chris Pennuto, University of Buffalo Dr. Jack Kramer, Heidelberg University Scott Winkler, EPA

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