Pesticide and nutrient inputs from human activities are present in the Sacramenot-San Joaquin Bay-Delta, but the impact of these stressors together on algae is not well known. This research will examine the impacts of herbicides and nutrients on the growth and stress responses of phytoplankton and cyanobacteria present in the San Francisco Estuary. The algae in the delta are diverse with critical ecological effects, ranging from toxin-producing cyanobacteria that form hazardous algal blooms to benthic diatoms and green algae that make up the bulk of the aquatic food web. Contaminants and herbicides can cause changes in algae cellular health which may impact population growth. Understanding algal sub-lethal stress responses will improve our understanding of stressors on the bay-delta food web and bloom formation.
The Environmental Monitoring Program (EMP) began in 1975 to conduct baseline and compliance monitoring of water quality, phytoplankton, zooplankton, and benthic invertebrates in the San Francisco Bay-Delta estuary. This monitoring program was designed to track the impact of water diversions to the State Water Project (SWP) and Central Valley Project (CVP) on the Bay-Delta. In the decades since, EMP scientists have monitored these constituents at fixed and floating stations throughout the estuary and ensured compliance with state and federal mandates such as Water Right Decision 1641 (D-1641). In the years and decades since its inception, EMP has become one of the cornerstones for scientists' and managers' understanding of the pace and pattern of change in this critical ecosystem. By sampling water quality and biological communities concurrently, EMP has created a dataset that is uniquely useful in better understanding causal connections between physical, biological, and biogeochemical processes.
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.
