Aquatic Ecosystems

The Biogeochemistry (BGC) Group uses an interdisciplinary approach to address surface water quality issues and food web dynamics throughout California, particularly in the Sacramento-San Joaquin Delta and San Francisco Bay.

The San Francisco Bay and Sacramento-San Joaquin Delta form one of the largest estuaries in the United States. Water flow and water quality in the San Francisco Bay-Delta Estuary are important to the economies of both California and the nation. The Bay-Delta system provides water to more than 25 million California residents and vast farmlands, as well as key habitat for birds, fish, and other...

Longfin Smelt ( Spirinchus thaleichthys) is a pelagic fish species found in waters along the Pacific coast, from Alaska to central California. Its complex life cycle makes it vulnerable to threats in both freshwater and at sea. Longfin Smelt is listed as a threatened species by the state of California.

Sediments represent an important pool of nutrients in the Sacramento-San Joaquin Delta (Delta). The exchange of nutrients between the water column and the benthos impacts water quality and effects phytoplankton, harmful algal blooms, aquatic vegetation, and drinking water quality. To date, there is very limited information about nutrient pools in Delta sediments, nor how these nutrients are...

Many non-native fish, invertebrates, and plants have colonized the Sacramento-San Joaquin Delta (Delta) of California, the landward most region of the San Francisco Estuary. Included among these invasive species is the water primrose ( Ludwigia spp .), an aggressive floating aquatic plant that is native to South and Central America and parts of the US, but invasive in California. Water primrose is...

Planned upgrades to the Sacramento Regional wastewater treatment plant (SRWTP) will substantially reduce nutrient discharge and also alter the types and amounts of nutrients being distributed across the San Francisco Delta and Estuary (Delta). One highly anticipated outcome of lower nutrients is improved productivity in the phytoplankton communities that supply aquatic food webs, which should...

California’s Sacramento-San Joaquin River Delta (Delta) provides drinking water to about 30 million people and irrigation water to the agriculturally rich Central Valley. The Delta is also home to numerous threatened and endangered native species. The health of the Delta's aquatic ecosystems, and fish in particular, have long been in a state of decline. This is associated with decreasing...

The abandoned Sulphur Bank Mercury Mine on the shores of Clear Lake in Northern California has been designated as a "Superfund Site" by the U.S. Environmental Protection Agency (EPA). This means that the EPA has determined that the area is contaminated by hazardous waste and requires cleanup because it poses a risk to human health and/or the environment. One of the chief contaminants at the site...

The Trinity River Restoration Program implements the Department of Interior directive to restore the fisheries of the Trinity River impacted by dam construction and related diversions. The multi-agency program is one of the nation’s largest adaptively managed river restoration efforts and requires periodic assessment to determine its effectiveness in restoring channel dynamics and habitat features...

Neonicotinoids are a new class of insecticides chemically related to nicotine. Like nicotine, they act on receptors in the nerves and are generally much more toxic to insects, than they are to mammals and other higher organisms. Their use has increased rapidly over the last decade, driven in large part by their use for seed coating. Seed coating is when a seed is treated with an insecticide prior...

Climate change and demographic changes have underscored the need to improve effectiveness of managing valuable water resources for sustainability. In 2014, the Sustainable Groundwater Management Act (SGMA) established a framework for sustainable, local groundwater management. SGMA requires groundwater-dependent regions to halt overdraft and bring basins into balanced levels of pumping and recharge...

Suisun Bay is an area identified as critical habitat for the threatened Delta Smelt. Several important changes in the pelagic food web of this area have been documented over the last two decades indicating that food for Delta Smelt and other threatened fishes is in short.