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Microcystin Concentrations, Partitioning, and Structural Composition during Active Growth and Decline: A Laboratory
Emily F Pierce1, Astrid Schnetzer1
1Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695, USA.
Toxins
|December 22, 2023
Summary
Microcystin dynamics show particulate toxins degrade quickly, but dissolved forms persist for months after cyanobacterial blooms. This impacts food-web transfer risks and requires updated monitoring strategies.
Area of Science:
- Environmental Science
- Ecotoxicology
- Microbiology
Background:
- Microcystins, potent algal toxins, exhibit variable concentrations, phases, and congener profiles impacting their environmental fate and toxicity.
- Understanding microcystin dynamics is crucial for assessing risks associated with cyanobacterial blooms.
Purpose of the Study:
- To investigate microcystin dynamics, including concentration, phase (dissolved/particulate), and congener changes, during cyanobacterial bloom degradation.
- To determine the persistence and half-life of microcystins in different phases.
- To inform risk assessments and monitoring strategies for cyanobacterial blooms.
Main Methods:
- Incubation experiments were conducted with six cyanobacterial bloom assemblages from the Chowan River, North Carolina.
- Microcystin concentrations, phases, and congener compositions were analyzed over time.
- Degradation rates and half-lives of particulate microcystin were calculated.
Main Results:
- Particulate microcystin showed rapid degradation, with an average half-life of 10.2 ± 3.7 days in five of six incubations.
- Dissolved microcystin remained detectable for up to 100 days, indicating prolonged persistence.
- Congener composition varied between phases and shifted over time, with MC-RR and MC-LR being most prevalent.
Conclusions:
- Concerns regarding food-web transfer of intracellular microcystins are highest during the initial weeks post-bloom peak.
- Dissolved microcystins pose a longer-term risk, persisting for months after bloom decline.
- Findings highlight the need for refined monitoring and risk assessment strategies considering microcystin phase and congener dynamics.
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