Publication Date
2025
Document Type
Thesis
Committee Members
Yvonne Vadeboncoeur, Ph.D. (Advisor); Katie Hossler, Ph.D. (Committee Member); Volker Bahn, Ph.D. (Committee Member)
Degree Name
Master of Science (MS)
Abstract
Benthic primary production is poorly quantified in the Laurentian Great Lakes relative to phytoplankton-based production. We measured benthic chlorophyll and benthic primary productivity on soft sediments and Dreissena shells along depth gradients in Lakes Erie (2024) and Michigan (2025) during EPA Cooperative Science and Monitoring Initiative cruises. We measured benthic chlorophyll fluorometrically and estimated benthic primary productivity using non-invasive oxygen exchange incubations. We used PAM fluorometry to characterize photosynthetic-irradiance relationships on mussel shells and sediments in Lake Michigan. In Lake Erie, sediment chlorophyll ranged from 20 to 150 mg m⁻², with highest values in the central basin. In Lake Michigan, sediment chlorophyll ranged from 50 to 500 mg m⁻² and exhibited a pronounced mid-depth peak at approximately 15 to 30 m. Mussel-associated chlorophyll declined with depth in both lakes and was largely restricted to sites shallower than about 40 m. In Lake Michigan, oxygen-based gross primary productivity on sediments was low but detectable (approximately 1 to 10 mg C m⁻² h⁻¹) and tended to peak at intermediate depths, broadly paralleling chlorophyll patterns. PAM fluorometry indicated physiologically active communities across the sampled depth range, although fluorescence-based parameters were weak predictors of oxygen-based productivity. In Lake Erie, oxygen-based productivity estimates were not reliable due to light interference affecting optical oxygen sensors. Together, these results support an intermediate-depth window where reduced shallow disturbance and sufficient bottom light allow benthic algal biofilms develop on both sediments and Dreissena shells.
Page Count
73
Department or Program
Department of Biological Sciences
Year Degree Awarded
2025
Copyright
Copyright 2025, all rights reserved. My ETD will be available under the "Fair Use" terms of copyright law.
ORCID ID
0009-0003-7398-9155
