Yvonne Vadeboncoeur, Ph.D. (Advisor); Volker Bahn, Ph.D. (Committee Member); Soren Brothers, Ph.D. (Committee Member); Katie Hossler, Ph.D. (Committee Member); Silvia E. Newell, Ph.D. (Committee Member)
Doctor of Philosophy (PhD)
Attached algae are ubiquitous components of lake benthic habitats wherever sufficient light reaches submerged surfaces. Attached algae interact with heterotrophic bacteria and fungi to form complex biofilms (“periphyton”) that provide a nutritious food source for consumers and influence biogeochemical cycling by regulating redox potential at the sediment-water interface. Despite their ecological importance, there are limited data on the role of periphyton in the Laurentian Great Lakes. I quantified wave exposure and light availability in rocky nearshore habitats in Lake Erie and Lake Huron. Periphyton biomass and productivity in nearshore Lake Erie was very high while algal biomass and productivity in Lake Huron were uniformly low irrespective of depth. Regression modeling demonstrated that wave disturbance and light availability control periphyton biomass and productivity in nearshore areas of the Great Lakes. To better understand how attached algal diversity and abundance vary with depth and substrate, I measured the biomass and composition of sediment algae and periphyton growing on Dreissena across broad depth gradients in Lake Ontario and Lake Erie. Sediment and mussel shell algal biomass were greatest around 20 m and declined with depth. Algal photosynthesis on sediments and mussels declined with depth down to approximately 40 m in both lakes. I found that sediments from both lakes were dominated by benthic diatoms and settled phytoplankton. In contrast, mussel shells harbored diverse filamentous algal assemblages. I analyzed the stable isotope signatures of Dreissena tissue and biofilms collected in Lake Ontario and Lake Erie, discovering enrichment of nitrogen isotopic signatures in both organisms with depth. DNA metabarcoding data from Lake Erie revealed that Dreissena biofilms harbor greater abundances of putative nitrifying and denitrifying bacteria than surrounding sediments, suggesting that Dreissena may be hotspots for nitrogen cycling in the Great Lakes. This work provides the first spatially extensive surveys of periphyton in the Great Lakes and reveals the composition, distribution, and function of these ecologically important assemblages. By encompassing perspectives on periphyton function and diversity from small to broad scales and across different physical conditions, this work is a critical step in understanding the role of periphyton in the Great Lakes.
Department or Program
Department of Earth and Environmental Sciences
Year Degree Awarded
Copyright 2021, some rights reserved. My ETD may be copied and distributed only for non-commercial purposes and may not be modified. All use must give me credit as the original author.
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.