David Senn

High nutrient concentrations can cause increased phytoplankton biomass, low dissolved oxygen, and increased harmful algal blooms and toxins, with detrimental effects on species and ecosystems. San Francisco Bay receives high nutrient loads mainly from discharged wastewater, but high turbidity, strong tidal mixing, and abundant filter-feeding clams have kept algal blooms in check. Following the historic algal bloom of 2022, regulators and managers recognize the Bay’s resilience to high nutrient loading is waning and nitrogen concentrations must be managed more proactively. 

San Francisco Bay has been experiencing a major harmful algae bloom (HAB) event. Early signs of the developing bloom were reported in late July 2022 within the Oakland Estuary (between Alameda and Oakland). By early August, the bloom had spread to South Bay west of Alameda, and by mid-August expanded over large swaths of South Bay. Recent observations suggest the bloom may also be reaching into regions of Central and San Pablo Bays. 

A team led by Dr. Jing Wu penned a paper in January on using Green Stormwater Infrastructure to protect the Bay from PCBs and other contaminants. "Optimal Selection and Placement of Green Infrastructure in Urban Watersheds for PCB Control" is now featured in the Editor’s Choice section of the Journal of Sustainable Water in the Built Environment for the American Society of Civil Engineers. 

Historically, freshwater was an important component of the baylands ecosystem, creating salinity gradients that added physical and ecological diversity to the baylands landscape as well as facilitating rapid vertical marsh growth. Today, the extent, magnitude, and seasonality of freshwater to the baylands has been greatly altered. This project brings together diverse stakeholders to further the conversation on using treated wastewater as a resource for a resilient East Bay shoreline.

The RMP Annual Meeting is held every year in the early fall. The meeting is an opportunity for RMP stakeholders to discuss current RMP projects and highlight interesting new research. 

This visualization tool facilitates intuitive comparison of continuous data from around the Bay, and across a variety of analytes, to demonstrate the potential for collaborative monitoring across programs.

The San Francisco Estuary Partnership (SFEP) brings together the estuarine community every two years at the State of the Estuary Conference and, periodically, SFEP also reports on the State of the Estuary, summarizing the latest scientific findings about ecosystem health. This State of the Estuary Report is the only place where a holistic view of ecosystem function is provided across both the Bay and the Delta. This year, SFEI provided scientific leadership and technical support for the report, which focuses on the ties between social and ecological resilience for our estuary.

San Francisco Bay is becoming clearer.

Decades of tidal action have finally washed away most of the mess created 150 years ago by Gold Rush miners who blasted apart hillsides in the Sierra Nevada. The result was millions of tons of mud, gravel and sand that made its way downriver and ended up in the bay, clouding its waters and coating the bottom with a level of silt up to 3 feet thick.

Most of the silt, scientists say, has now moved out to the ocean.

Dr. David Senn's nutrients program is highlighted in the San Francisco Examiner as his work to measure and predict the effects of an ever-clearer San Francisco Bay again "come to light":

In an event convened by the San Francisco Estuary Partnership, SFEI contributed its own intellectual labor to the State of the Estuary Conference. Letitia Grenier served as the lead scientist for the State of the Estuary Report, unveiled at the gathering, and SFEI's scientists and technologists were featured prominently in the program on subjects ranging from nutrients to landscape resilience to green infrastructure to data and tools. By all measures, it was a successful conference.

Many news outlets are reporting on a spike in leopard shark deaths and bat rays in S.F. Bay.  Several theories related to pollution have been offered, but we want to offer an additional factor that is missing from the discussion...

SFEI scientists studying the role and effects of nutrients in the Bay recently completed two draft reports that summarize current knowledge of the issue. 

This visualization tool facilitates intuitive comparison of continuous data from around the Bay, and across a variety of analytes, to demonstrate the potential for collaborative monitoring across programs.