In-situ rapid monitoring of phytoplankton community to investigate role of iron during cyanobacterial dominance

Thumbnail Image
Date
2021-08
Authors
Leung, Tania
Major Professor
Advisor
Swanner, Elizabeth
Caissie, Beth
Ikuma, Kaoru
Wilkinson, Grace
Zhou, Yuyu
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Altmetrics
Authors
Research Projects
Organizational Units
Journal Issue
Is Version Of
Versions
Series
Department
Geological and Atmospheric Sciences
Abstract
The occurrence of algal blooms throughout the United States are a widespread threat to freshwaters. Cyanobacteria are the predominant members of a bloom and some species are known to produce toxins that harm human and animal health. In Iowa, the occurrence of these blooms and toxins in past years has led to recreational water use advisories. To mitigate such events, efforts are focused on monitoring and understanding drivers of algal blooms so that researchers and water resource managers are able provide early warning systems to the public. However, there are challenges in detecting and monitoring algal blooms. Large geographic areas are difficult to monitor with limited resources (labor, analytical tools). Moreover, the link between environment conditions and phytoplankton proliferation is not always clear. While nutrients such as nitrogen and phosphorus drive phytoplankton overgrowth, some studies also suggest a link to the micronutrient iron. The underlying mechanisms driving phytoplankton biomass remains an active topic of research. It is urgently important to implement methods to detect and monitor algal blooms and assess risk exposure. Putting science to practice, this study collaborates with Iowa Department of Natural Resources to protect water quality and aims to adapt a cost-efficient and scalable approach for monitoring algal blooms and to determine parameters, including micronutrient (i.e., Fe), regulating their growth. Understanding the dynamics of bloom biomass will aid water resource managers and researchers to provide early warning systems to the public. To this end, this study has three objectives: First, multi-wavelength fluorometer was implemented to detect algal blooms and monitor their development in Iowa’s lakes, which provided the ability to use a quickly capture the dynamics in phytoplankton community composition. The multi-wavelength fluorometer can accurately detect cyanobacteria and diatoms/dinoflagellate members of the phytoplankton community but is less reliable for detecting chlorophytes, euglenophytes, and any phycoerythrin-rich phytoplankton. By monitoring the succession of phytoplankton community, it becomes possible to link bloom dynamics with environmental conditions, specifically iron. The second part of this dissertation surveyed dissolved iron (DFe) concentrations in Iowa’s lakes. Results from this survey show DFe distribution varies across Iowa’s lakes and carry a temporal effect. For majority of lakes in Iowa, DFe generally decline into June and July and climb back up in August and September. While many factors affect this curvilinear relationship, the combination of factors driving this trend varies from lake to lake. Finally, this dissertation investigated the role of iron during a bloom event (monitored by multi-wavelength fluorometer) at East Okoboji Lake in northwestern Iowa. Results indicated that DFe was not a limiting nutrient in this lake and iron abundance could potentially sustain phytoplankton growth. Instead, phytoplankton strongly correlated with increased phosphorus. Together, this study puts research to practice by adapting a scalable tool to detect and monitor CyanoHABs, which will help water resource managers to develop strategies that will minimize risk exposure and mitigate harmful effects. As a data product, measured DFe concentrations in Iowa’s lake serve as a resource for not only the limnology community.
Comments
Description
Keywords
Citation
Source
Copyright