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Direct and indirect animal-mediated biogeochemical effects on nutrient dynamics in coastal Lake Erie ecosystems

Michael, Taylor Courtney
http://orcid.org/0000-0002-5685-5396
http://rave.ohiolink.edu/etdc/view?acc_num=kent1713790993717644

Abstract Details

2024, PHD, Kent State University, College of Arts and Sciences / Department of Biological Sciences.
Freshwater aquatic ecosystems, including lakes and wetlands, provide habitat for abundant and diverse animal communities, which can have large impacts on nutrient (nitrogen [N] and phosphorus [P]) biogeochemistry. Animals play an important role in nutrient recycling in freshwater ecosystems but are infrequently considered in nutrient management. It is broadly known that animals provide nutrients via excretion and egestion, however, less is known about how animals indirectly influence nutrient retention and release through interacting with aquatic sediments, and how their nutrient contributions shape aquatic communities and ecosystem functions such as primary production. Waterbirds (i.e., ducks, geese, wading birds, cormorants) and benthic invertebrates (i.e., benthic dwelling oligochaete worms, insect larvae such as mayfly and chironomid taxa) are common in Great Lakes aquatic ecosystems, yet their roles in shaping nutrient budgets and loading are often overlooked. The overall focus of this dissertation was to understand how sediment-surface water nutrient dynamics and ecosystem processes are shaped by aquatic animals and different water oxygen conditions in a variety of Great Lakes freshwater aquatic ecosystems. We demonstrate that multiple animal groups can measurably shape nutrient dynamics with implications on other ecosystem functions. In the first study, we investigated multiple internal load contributions, including net ambient and bioturbator-mediated sediment-surface water nutrient exchange, in Sandusky Bay, Lake Erie. We found that invertebrate bioturbation supplied P and N and made up a significant component of net internal fluxes, and internal sources made up a significant proportion of the total P load in this shallow, freshwater embayment. In the second study, we examined how the late-summer hypoxic event in Lake Erie shapes sediment oxygen and redox-sensitive indicators to better understand how hypoxia stressors affect sediment conditions and processes that are important in determining internal nutrient loading. We found that hypoxic conditions alone had little impact on sediment oxygen availability and redox-sensitive measures (e.g., phosphorus sorption), suggesting that sediment conditions are resistant to changes from temporary hypoxic events. In the third study, we experimentally manipulated benthic bioturbating invertebrate densities in a managed Lake Erie coastal wetland to elucidate how invertebrate bioturbators alter sediment nutrient retention and release in real environmental conditions. We found that increasing bioturbator densities were positively associated with P and N fluxes (release of nutrients from sediments into surface waters) and may help shape nutrient fluxes in-situ. In our fourth study, we investigated how waterbirds shape nutrient budgets via guano inputs and how waterbird guano can be taken up by wetland sediments and can shape algal communities in Great Lakes coastal wetlands. We found that waterbirds provide substantial nutrient fluxes, however, wetland sediments retain most of the guano-derived P but only about half of the guano-derived N. Overall, guano-derived nutrient fluxes make up a negligible component of the external nutrient loads from the surrounding agricultural landscape. We found that algal communities shift in response to different waterbird guano, but all maintain diverse assemblages without high numbers of toxin-producing cyanobacteria. Overall, animals may not provide a substantial contribution of nutrients at the whole-ecosystem scale when compared to external loading sources in agricultural landscapes. However, nutrients recycled by animals may be important locally, in areas or during times when nutrient conditions are limiting to primary producers, and may help shape ecosystem functions at small spatial and temporal scales. Considering animal effects at the ecosystem level will be important for determining management goals in a landscape that prioritizes both animal habitat and nutrient reduction.
David Costello (Advisor)
Lauren Kinsman-Costello (Committee Member)
Ferenc de Szalay (Committee Member)
Michael Vanni (Committee Member)
Allyson Tessin (Committee Member)
249 p.
Biogeochemistry; Ecology; Environmental Science; Freshwater Ecology; Limnology
ecosystem ecology, nitrogen, phosphorus, oxygen, Great Lakes, consumer-driven nutrient recycling, bioturbation and bioirrigation, nutrient fluxes

Recommended Citations

Citations

  • Michael, T. C. (2024). Direct and indirect animal-mediated biogeochemical effects on nutrient dynamics in coastal Lake Erie ecosystems [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1713790993717644

    APA Style (7th edition)

  • Michael, Taylor. Direct and indirect animal-mediated biogeochemical effects on nutrient dynamics in coastal Lake Erie ecosystems. 2024. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1713790993717644.

    MLA Style (8th edition)

  • Michael, Taylor. "Direct and indirect animal-mediated biogeochemical effects on nutrient dynamics in coastal Lake Erie ecosystems." Doctoral dissertation, Kent State University, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=kent1713790993717644

    Chicago Manual of Style (17th edition)

kent1713790993717644
370
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This open access ETD is published by Kent State University and OhioLINK.