San Francisco

Scientists Launch First Long-Term Effort to Measure Acidification in San Francisco Bay

Climate Change


​Visitors to the Tiburon shoreline may notice a new addition to the seascape—a five-foot-tall, bright yellow buoy anchored just offshore San Francisco State University’s Estuary & Ocean Science (EOS) Center. The Bay Ocean Buoy (BOB) and its companion mooring for Marine Acidification Research Inquiry (MARI) bring together researchers at San Francisco State, University of California, Davis, and funders. It represents the first effort to perform long-term scientific monitoring of ocean acidity and carbon dioxide in the waters of the bay.

“By monitoring the carbon chemistry of the San Francisco Bay, we will learn how global climate change and changing ocean chemistry are interacting with local habitat restoration and conservation efforts,” said Dr. Karina Nielsen, director of the EOS Center and SF State biology professor. “It will enable us to recognize the most promising management solutions and make better investments to promote the environmental health of the bay, benefiting both people and wildlife.”

Waters from the Pacific Ocean and the Sierra meet in San Francisco Bay. In terms of pollution, the focus traditionally has been on the water brought to the bay by rivers and runoff from the land. However, deep, cold ocean waters that upwell along the California coast may bring their own issues. A portion of the carbon dioxide released into the atmosphere by burning fossil fuels is absorbed by the world’s oceans, making them more acidic. This acidity has the potential to affect a variety of marine and estuarine life, such as oysters, mussels and crabs that use calcium carbonate to build their shells and other hard body parts. 

“Eventually we will have a finger to place on the pulse of major chemical changes that we expect are happening in San Francisco Bay in response to global environmental changes in the ocean and watershed,” said Dr. John Largier, associate director of UC Davis’ Coastal and Marine Sciences Institute and a professor of oceanography in the campus’s department of environmental science and policy.

To track these changes, the newly deployed BOB and MARI moorings carry sensors for measuring carbon dioxide—in the atmosphere and the water—dissolved oxygen, pH, chlorophyll a (a measure of the amount of microscopic algae in the water), water clarity, temperature and salinity. The sensors will make measurements at the surface, and also deep in the bay where ocean waters flow in.

The moorings are intended to be long-term additions to the shoreline. Along with providing an immediate snapshot of water conditions, the collected data will let scientists assess how changing ocean waters are affecting the long-term health of the bay. They’ll also assist in tracking the success of efforts to manage local water quality and to conserve and restore natural habitats.

“EPA is pleased to support many varied aspects of San Francisco Bay water quality monitoring,” said Alexis Strauss, U.S. Environmental Protection Agency’s acting regional administrator for the Pacific Southwest. “These new sensors are a welcome addition to help us understand changing conditions in the bay.”

The project is funded by the U.S. Environmental Protection Agency through the San Francisco Estuary Partnership and by the Central and Northern California Ocean Observing System (CeNCOOS), a regional association of the National Oceanic and Atmospheric Administration’s (NOAA’s) U.S. Integrated Ocean Observing System. The Carbon Group at NOAA’s Pacific Marine Environmental Laboratory also contributed time and expertise. This initiative adds new capabilities to the network of shore stations supported by CeNCOOS.