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Testing the algal loading hypothesis: the importance of Sandusky River phytoplankton inputs to offshore Lake Erie processes

Conroy, Joseph David
http://rave.ohiolink.edu/etdc/view?acc_num=osu1186592400

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Evolution, Ecology, and Organismal Biology.
Studies of tributary-lake interactions most often consider only tributary nutrient stimulation of offshore phytoplankton growth. However, in freshwater ecosystems, input of tributary phytoplankton may directly affect offshore processes, such as nutrient cycling, phytoplankton-bloom formation, and hypolimnetic hypoxia. To explore these interactions, we propose the Algal Loading Hypothesis which predicts (1) tributaries contain phytoplankton; (2) tributary phytoplankton are light-limited due to high nutrient concentrations and high light attenuation; (3) offshore phytoplankton are nutrient-limited due to low nutrient concentrations and low light attenuation; and, (4) as tributary phytoplankton move offshore, productivity increases in response to greater light availability, using tributary-stored nutrients to drive offshore productivity. We used field sampling during April-September 2005 and 2006, phytoplankton physiological measures, and computer simulations to test these predictions and to determine the effect of loaded phytoplankton on offshore phytoplankton dynamics and hypolimnetic oxygen depletion in the Sandusky system (Sandusky River, Bay, and subbasin) of Lake Erie. We found extremely high phytoplankton biomasses in the Sandusky River and Bay (Chapter 2) including an invasive cyanobacterial phytoplankter, Cylindrospermopsis(Chapter 5). Phytoplankton biomass was best predicted by the ratio of total inorganic nitrogen to total phosphorus (Chapter 2) whereas Cylindrospermopsisbiomass correlated with increased temperatures and shallow depths (Chapter 5). River and bay phytoplankton communities were not phosphorus limited but the offshore phytoplankton community was (Chapter 3). Phytoplankton communities at all sites were not strictly light limited; however, simulated phytoplankton productivity was most sensitive to light availability. For example, when we simulated increased light for the bay phytoplankton community, productivity increased > 200% (Chapter 3). Hypolimnetic oxygen depletion rates, however, were not affected by bay input of particulate organic matter but were most strongly influenced by basin morphometry (Chapter 4). Overall, we found support for the predictions of the Algal Loading Hypothesis with the exception of light limitation for tributary phytoplankton. Input of tributary phytoplankton “primed” for growth offshore must be considered when attempting to manage offshore water quality, especially in a system extensively modified by human activity, such as Lake Erie.
David Culver (Advisor)
243 p.
Lake Erie; phytoplankton; Cyanobacteria; Sandusky River; Sandusky Bay; phosphorus; oxygen

Recommended Citations

Citations

  • Conroy, J. D. (2007). Testing the algal loading hypothesis: the importance of Sandusky River phytoplankton inputs to offshore Lake Erie processes [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1186592400

    APA Style (7th edition)

  • Conroy, Joseph. Testing the algal loading hypothesis: the importance of Sandusky River phytoplankton inputs to offshore Lake Erie processes. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1186592400.

    MLA Style (8th edition)

  • Conroy, Joseph. "Testing the algal loading hypothesis: the importance of Sandusky River phytoplankton inputs to offshore Lake Erie processes." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1186592400

    Chicago Manual of Style (17th edition)

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© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.