| dc.description.abstract | Cyanobacterial blooms and toxins have harmful impacts on global aquatic ecosystems.
Within this, their impact on the water quality of freshwater systems are particularly troublesome.
My research investigated methods to both monitor and control cyanobacterial blooms and toxins
to assist resource managers with this pressing aquatic resource issue.
My monitoring research included identifying the environmental drivers of microcystin, a
hepatotoxin produced by select cyanobacteria, using both a linear meta-analytical analysis and
non-linear generalized additive modeling approach. Linear meta-analysis of 2,643 global fresh
waterbodies indicated that chlorophyll, total dissolved phosphorus, total phosphorus, and Secchi
disk depth were the strongest water quality parameters related to microcystin occurrence. On the
other hand, non-linear analysis of 2,040 global fresh waterbodies indicated that total nitrogen,
turbidity, pH, and Secchi disk depth were the strongest water quality parameters related to
microcystin occurrence. Although similarities were found between these two approaches, my
findings suggest trends in cyanobacterial data may be non-linear, and utilizing non-linear
analyses to assess such data are recommended.
To control cyanobacterial blooms, I compared the effectiveness of 7 different algaecides
(including copper-, hydrogen peroxide (H2O2)-, peracetic acid-, and clay-based products) in a 35-
day field experiment, and also assessed the nuanced effectiveness of H2O2 under varying
environmental conditions. In general, it was found that copper-based products remain the most
efficient and cheapest choice to reduce total phytoplankton biomass in aquaculture systems.
However, peracetic acid-based products effectively reduced cyanobacteria while having marginal
effects on beneficial algae and zooplankton. Such algaecides could be effective alternatives to
copper-based products depending on the outcomes sought by resource managers.
Lastly, my laboratory study of H2O2 assessed its effectiveness at reducing cyanobacteria
under different environmental conditions, including varying dissolved organic matter
concentrations, temperatures, and starting phytoplankton concentrations. Neither variation in
dissolved organic matter concentration nor temperature influenced the effectiveness of H2O2 at
reducing cyanobacteria. However, initial phytoplankton density as well as H2O2 dose greatly
influenced the effectiveness of the algaecide. Thus, water resource managers are encouraged to
consider how ambient conditions may alter the ability H2O2 to control algal blooms prior to
treatment. | en_US |
