Date of Award

5-16-2024

Publication Type

Thesis

Degree Name

M.Sc.

Department

Earth and Environmental Sciences

Keywords

Biofouling;Community composition;Microbial colonization;Microbial ecology;Microbial succession;Optical sensors

Supervisor

Aaron Fisk

Supervisor

Sophie Crevecoeur

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

The western Basin of Lake Erie is a warm-water, shallow, eutrophic freshwater system, with intense regularity of notorious cyanobacteria-dominate harmful algal bloom events (cHABs). As a result of cHAB-related freshwater degradation, water quality monitoring efforts have greatly expanded over recent decades, with the introduction of high-temporal frequency data provided by long-term sensors. The application of in situ sensors is restricted by the establishment of aquatic biofouling, which extremely limits the efficacy of optical sensing, often utilized for measuring physiochemical properties of water quality. Further, understanding of the species comprising biofouling communities is relatively limited. Therefore, this thesis focused on biofouling in two regards: (i) its impact on optical sensor measurements, and (ii) the bacterial community composition of biofouling. The first study assessed biofouling growth and subsequent performance of two long-term monitoring optical-based sensor types. Biofouling was found to impact all sensors, negatively affecting measurement integrity as soon as 7-33 days of deployment. There were clear patterns in parameter overestimation by fouled chlorophyll sensors and dissolved oxygen sensors near bottom, whereas fouled dissolved oxygen sensors near surface underestimated, indicating potential influence of fouling structure and sensing properties. The second project evaluated bacterial plankton and biofouling communities, finding that biofouling greatly differed from adjacent plankton. Within the biofouling samples, there was distinct heterogeneity of communities with depth and time, while plankton was homogenous. Despite biofouling exhibiting significant dissimilarity at the beginning of the study (≤ 54 days), there was a convergence in community composition leading to non-significant variation between communities at ≥ 93 days. Freshwater biofouling presents a nuisance to optical sensing instruments. However, its complexity of occupying organisms offers a new perspective on microbial interactions that allows for greater understanding of bacterial community structure and succession patterns over time.

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