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Fazekas_HM_Dissertation_2018.pdf (2.54 MB)

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River biofilm structure and function in a resource landscape modified by agriculture: implications for primary consumers

Fazekas, Hannah M.
http://rave.ohiolink.edu/etdc/view?acc_num=wright1535118088003803

Abstract Details

2018, Doctor of Philosophy (PhD), Wright State University, Environmental Sciences PhD.
Anthropogenic alterations to nitrogen, carbon, and phosphorus bioavailability have increased the flux of these resources into the biosphere and altered stream ecosystem function. Streams modify the transport of these resources to receiving ecosystems through uptake, transformation, and mineralization. Understanding how streams process carbon, nitrogen, and phosphorus can provide insight about how stream ecosystems function in landscapes where human modification is inescapable. I investigated how land use in agricultural regions affect resource availability to primary producers and consumers and the subsequent impact on stream processes. I surveyed headwater streams in three Lake Erie watersheds to determine spatiotemporal nutrient limitation of attached algae. I found that low-order streams exhibit phosphorus limitation and the severity of phosphorus limitation was greatest post-fertilizer application when the imbalance between water column nitrogen: phosphorus concentrations was greatest. These results suggest that biofilm nutrient uptake responded to landscape level influences and attached algae actively sequestered phosphorus from the water column. Agriculture alters the availability of carbon through modification of riparian vegetation. I used genomic techniques to describe longitudinal changes in microbial community composition along a stream with headwaters that lacked riparian vegetation due to row crop agriculture but the width of the forested riparian area increased downstream. The relative abundance of the most abundant microbial phyla varied along physical and chemical (light, phosphorus concentration) gradients. Land use affected physical-chemical characteristics of the river, which in turn, influenced sediment microbial community composition. The removal of riparian forested vegetation leads to increased light availability to attached algae. I investigated the effect of attached algal productivity on consumers across an experimental gradient in light intensity. Attached algal productivity and consumer production were coupled across the light gradient. I also studied how land use influenced carbon resource use by common macroinvertebrate functional feeding groups in Midwestern streams. I found that invertebrates consistently used attached algal carbon. This reliance was not affected by riparian vegetation nor the percent of the watershed dedicated to agriculture. Food web structure remained similar across the gradient in land use. This work demonstrates that attached assemblages in streams respond to landscape level processes that propagate to consumers.
Yvonne Vadeboncoeur, Ph.D. (Advisor)
David Strayer, Ph.D. (Committee Member)
Katie Hossler, Ph.D. (Committee Member)
Lynn Hartzler, Ph.D. (Committee Member)
John Stireman III, Ph.D. (Committee Member)
195 p.
Biology; Ecology; Environmental Science
streams; attached algae; biofilm; land use; consumers; nutrient limitation; primary productivity; food webs;

Recommended Citations

Citations

  • Fazekas, H. M. (2018). River biofilm structure and function in a resource landscape modified by agriculture: implications for primary consumers [Doctoral dissertation, Wright State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=wright1535118088003803

    APA Style (7th edition)

  • Fazekas, Hannah. River biofilm structure and function in a resource landscape modified by agriculture: implications for primary consumers. 2018. Wright State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=wright1535118088003803.

    MLA Style (8th edition)

  • Fazekas, Hannah. "River biofilm structure and function in a resource landscape modified by agriculture: implications for primary consumers." Doctoral dissertation, Wright State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1535118088003803

    Chicago Manual of Style (17th edition)

wright1535118088003803
417
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This open access ETD is published by Wright State University and OhioLINK.