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Pathways and Consequences of Contaminant Flux to Acadian Flycatchers (Empidonax virescens) in Urbanizing Landscapes of Ohio, USA

Rowse, Linnea M
http://rave.ohiolink.edu/etdc/view?acc_num=osu1374082536

Abstract Details

2013, Master of Science, Ohio State University, Environment and Natural Resources.
Increases in urbanization with a growing global population can result in diverse threats to wildlife, including exposure to harmful contaminants. Among environmental contaminants hazardous to humans and wildlife, mercury is of special concern due to its prevalence, mobility in aquatic systems, and persistence in sediments. Aquatic systems, in particular, can have high amounts of mercury in its bioavailable form, which can bioaccumulate in insects and transfer to terrestrial food webs (i.e., to aerial insectivores). Such contaminant flux from aquatic to terrestrial systems is expected to disproportionately affect species reliant upon aquatic emergent insects. To understand the pathways of contaminant flux and their role in reproductive success, I addressed two questions: (1) Is avian exposure to contaminants influenced by territory placement? and (2) Do contaminant loads negatively impact condition and reproductive success? From April-August 2011-2012 I tracked reproductive success of Acadian flycatchers (Empidonax virescens) in 19 riparian forest fragments located across a land-use gradient in central Ohio, USA. I collected blood samples from adult (n = 76) and nestling (n = 17) flycatchers and samples from riparian systems (sediment, aquatic emergent insect, and water) to examine relationships between landscape factors and contaminant concentrations. I used reproductive data and flycatcher contaminant loads to evaluate mercury’s impact on productivity and condition of adult flycatchers. Factors most responsible for contaminant transfer to flycatchers remain unclear. Landscape factors, including proximity of territories to rivers, and urbanization surrounding forest sites, were not related to mercury levels in flycatchers, sediment, water, or insects. However, when separately analyzed, I detected a positive relationship between mercury in flycatchers and sediments in urban landscapes, and an opposite, negative relationship, in rural landscapes. Unlike previous research, mercury concentrations in aquatic insects were not predicted by concentrations in sediments. The overall lack of concordance among mercury levels in flycatchers, aquatic insects, and sediments raises the possibility that flycatchers consumed less aquatic prey than expected or that the common aquatic insects were not the most important vectors of aquatic-to-terrestrial contaminant flux. Although levels of mercury in Acadian flycatcher blood in this study were relatively low and appeared not to affect body condition, productivity declined with increasing mercury loads. My results are consistent with other studies that have documented reduced reproductive success in contaminated areas, though mercury loads were at trace levels in the flycatchers I studied. Reduced productivity in my study system could possibly be explained by changes in adult behavior or egg hatching success, driven by sublethal effects of mercury in flycatchers; these factors need to be further examined. As a whole, my research contributes to a growing body of knowledge regarding pathways for contaminant flux from aquatic to terrestrial systems, and to our understanding of mercury contamination effects on songbirds. My research suggests that pathways for contaminant flux from aquatic to terrestrial systems are complex and do not always follow predictable routes. Moreover, that reduced productivity was associated with trace levels of mercury is a cautionary note that wildlife managers should not dismiss impacts of trace levels of contaminants that biomagnify.
Amanda Rodewald (Advisor)
Mažeika Sullivan (Advisor)
Roman Lanno (Committee Member)
121 p.
Toxicology; Wildlife Management
Mercury; Acadian Flycatcher; reproductive success; contaminant pathways

Recommended Citations

Citations

  • Rowse, L. M. (2013). Pathways and Consequences of Contaminant Flux to Acadian Flycatchers (Empidonax virescens) in Urbanizing Landscapes of Ohio, USA [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1374082536

    APA Style (7th edition)

  • Rowse, Linnea. Pathways and Consequences of Contaminant Flux to Acadian Flycatchers (Empidonax virescens) in Urbanizing Landscapes of Ohio, USA. 2013. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1374082536.

    MLA Style (8th edition)

  • Rowse, Linnea. "Pathways and Consequences of Contaminant Flux to Acadian Flycatchers (Empidonax virescens) in Urbanizing Landscapes of Ohio, USA." Master's thesis, Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1374082536

    Chicago Manual of Style (17th edition)

osu1374082536
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© 2013, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.