The Sacramento-San Joaquin Delta (Delta) faces a serious threat from the recent proliferation of cyanobacterial harmful algal blooms (cyanoHABs), particularly due to the production of high levels of cyanobacterial toxins. These blooms jeopardize water quality and pose a significant risk to air quality when toxins are released as particles in a process known as aerosolization. When people inhale these aerosols, it can trigger an inflammatory response, yet the specific form in which toxins are aerosolized remains unknown. Thus, an improved understanding of cyanobacterial toxin aerosolization mechanisms has significant human health implications. To assess the public health risks associated with airborne cyanobacterial toxins, the project examined the size distribution of cyanoHAB aerosols and the factors influencing their aerosolization. They also investigated the role of nutrient enrichment in cyanoHAB growth, cyanobacterial toxin production, and cyanotoxin aerosolization through a combination of laboratory and field experiments.
Project Objectives
1. Investigate and quantify the production of primary spray aerosols during cyanoHABs
2. Assess the linkage of nutrient enrichment, phytoplankton community composition, toxin production, and cyanoHAB aerosol formation
This project addresses a pressing environmental and public health concern. The data can be used to protect vulnerable communities living near affected bodies of water and inform ways to mitigate the adverse impacts of cyanoHABs on the Delta’s environmental and public health.
This research improves Delta-specific human exposure guidelines to cyanoHAB aerosols by providing data essential for implementing effective public health measures, including recommendations on mask usage and understanding the expected way aerosols travel through the air from the shoreline. Their investigation into the relationship between nutrient availability, cyanoHABs growth dynamics, toxin production, and aerosol formation will offer valuable insights for management efforts aimed at regulating algal blooms to improve both water and air quality outcomes. Ultimately, this research will strengthen state agency responses to human illness associated with cyanoHABs and toxin exposure.
Cyanobacteria are the most common plankton causing harmful algal blooms in freshwater. The variety of cyanotoxins produced by cyanobacteria can impact the nervous system, liver, gastrointestinal tract, respiratory system, and skin of humans and other animals. In the Sacramento-San Joaquin Delta (Delta), cyanobacterial harmful algal blooms (cyanoHABs) have become more prevalent since the late 1990s. Even with the welldocumented occurrence of cyanoHABs in the Delta over the last 15 years, there is no consistent monitoring program in the region, making it challenging to identify management actions to mitigate their occurrence and effects.
To fill this knowledge gap, this project focused on measuring cyanotoxins and cyanoHABs in the Delta, organizing relevant data for stakeholders, and synthesizing data about cyanoHAB extent and drivers. In addition to the generation of new data, this project developed tools to integrate existing and future data collection efforts. Synthesis of these data will help assess the status and trends of cyanoHABs in the Delta, elucidate factors contributing to bloom formation, cyanotoxin production, and transport, and ultimately better understand the effects of cyanoHABs on humans, other animals, and the ecosystem.
Since 2015, the DIISC Team has organized a biennial Delta Invasive Species Symposium. The symposium is a forum for Delta managers, researchers, and decision-makers to meet, share and synthesize information, and communicate best practices and lessons learned. https://deltaconservancy.ca.gov/diisc-team-activities/
