Photo of the estuarine landscape near the Sacramento-San Joaquin River Delta, featuring marsh greenery in the foreground and rolling hills in the background.
California tule and native salt grasses mingle with introduced species like pampas grass and palm trees on the banks of the estuaries’ expanse of islands. (Credit: Marilyn Sargent/Berkeley Lab)

A central hub of California’s water infrastructure, the Delta is not only ecologically rich, but also supplies freshwater to two-thirds of the state’s population and a $50 billion agricultural industry that serves the entire country. And while life in the Delta has continued to persist amidst almost constant human interference, from intensive manipulation of the area’s natural hydrology and salinity to the arrival of introduced species and high levels of agricultural runoff, the changing climate presents a growing challenge for an already sensitive ecosystem. In 2022, higher temperatures and extended drought created the conditions for a record-breaking toxic algal bloom, which killed thousands of fish and turned the waters of the San Francisco Bay — from Emeryville to Albany — a deep reddish-brown.  

There’s strong evidence that microbes have an outsize impact on nutrient cycling, which plays a significant role in triggering harmful algal blooms. But experts currently don’t know which microbial species live in the Delta or exactly how they function.

That’s why Lui, who grew up in Sacramento and has deep familial roots in the area going back six generations, is set on uncovering how the Delta’s microscopic life impacts the ecological health of this area and the quality of California’s drinking water. 

Research scientist Lauren Lui smiles while looking out at the blue-green waters of the Sacramento-San Joaquin River Delta from the deck of a boat. The Antioch bridge is visible in the distance.
Lauren Lui, a research scientist with Berkeley Lab’s Biosciences Area, rode aboard the research vessel Sentinel to survey the microbes of the San Francisco Estuary near the Sacramento-San Joaquin River Delta. Credit: Marilyn Sargent/Berkeley Lab

“It fascinates me that there are all these little things in the soil and the water that affect us,” Lui said. “We’re trying to understand what is going on out here and how everything is working together to trigger these harmful algal blooms. If we can figure out what the tipping points and levers of the system are, that can inform policy on how to manage our ecosystems.”

Wake from boat in SF Bay Estuary
(From left) Pedro Morais (Scientific Aide, Environmental Monitoring Program or EMP) and Betsy Wells (Environmental Scientist, EMP) on the Sentinel research vessel, run by the California Department of Water Resources, traveling to different parts of the San Francisco Estuary for researchers to collect various samples on Thursday, September 12, 2024 in Antioch, Calif. —- Lauren Lui, a research scientist with Biosciences’ Environmental Genomics and Systems Biology (EGSB) Division, is gathering microbiome samples from estuaries near Grizzly Bay in the Sacramento-San Joaquin River Delta. Lui will use genetic sequencing to identify the organisms present in these samples and study how they may be impacting important ecological processes like nutrient cycling and harmful algal blooms.
View from the deck of the research vessel Sentinel looking out over one of the San Francisco Estuary’s wide open channels near the Sacramento-San Joaquin river Delta. Two field ecologists set up equipment in the foreground on the boat's deck.
The Sentinel chugs along one one of the estuary’s wide open channels near Grizzly Bay. (Credit: Marilyn Sargent/Berkeley Lab)

Read the full story and explore Lui’s journey conducting her field sampling on the research vessel Sentinel on the Berkeley Lab News Center.