Aquatic Ecosystems

The proposed study is designed to better establish relationships between patterns of delta smelt abundance and properties of suspended particles as measured by optical and acoustical techniques.

Phytoplankton are an important part of aquatic food webs and ecosystems. These single-celled plants grow faster in the stronger light of spring or summer, resulting in population explosions called phytoplankton blooms. These blooms in turn feed zooplankton (free-floating aquatic microorganisms), providing food for many aquatic species, including fish, shrimp, crabs, and other invertebrates.

Tidal marshes provide animal habitats and prevent erosion. Expanding towns and cities have claimed major parts of San Francisco Bay’s marshland. Sediment deposits are essential to rebuilding tidal marshes and keeping existing marshes intact. In the southern part of the Bay, the largest tidal wetland restoration project on the west coast is underway. Sediment flux measurements are key in deciding...

Suspended-sediment measurements are essential for coastal planning, resource management, and for assessing the sustainability of salt marshes in relation to expected sea-level rise. Suspended sediment can have positive or negative effects, depending on its characteristics and amount, and on the location and ecosystem services of interest. Sediment deposition in salt marshes helps sustain marsh...

The Sacramento-San Joaquin Delta of California was once a great tidal freshwater marsh. It is blanketed by peat and peaty alluvium deposited where streams originating in the Sierra Nevada, Coast Ranges, and South Cascade Range enter San Francisco Bay. In the late 1800s, levees were built along the stream channels, and the land thus protected from flooding was drained, cleared, and planted (...

Accurate river-sediment data is fundamental to planning and managing river restoration efforts on the Trinity River, and throughout the world’s waterways. The USGS has developed a “hydrophone” that enables scientists to listen to sediment particles as they move along the riverbed in order to inexpensively and reliably record near-continuous sediment-bedload-transport data. For this study...

Rivers, wetlands, and agricultural operations supply natural organic material to the Sacramento-San Joaquin Delta (Delta) and the San Francisco Estuary. This natural organic matter provides many ecosystem benefits, but it also adversely affects drinking water. During drinking water treatment, chlorine added for purposes of pathogen control reacts with dissolved organic carbon (DOC) in the water to...

Scientists investigate excessive nutients levels in Rodeo Lagoon that are believed to be cause of dying fish

The project focuses on the assessment of aquatic biology, habitat, and water quality conditions of the major WHIS watersheds

Historic landuse, dam construction, water storage and flow diversion within the Trinity River watershed resulted in downstream geomorphic changes that simplified the river planform and lead to dramatic losses of salmonid habitat and significant population declines. The Trinity River Restoration Program (TRRP) requested the USGS complete an assessment of geomorphic change that could be used to...

The SWRCB has requested assistance from the USGS in analyzing the factors that control Hg concentrations in fish tissue in the Sierra Nevada. Specifically, the SWRCB wants to know whether Hg and (or) MeHg in bed sediment and (or) suspended sediment could be potentially useful in the future as a 303(d) listing criteria. The SWRCB has requested that the USGS perform an analysis of existing data for...

Newly-developed, commercially-available sensors permit real-time collection of water quality data that may help identify ecosystem processes that affect the health of pelagic food webs in the Sacramento – San Joaquin Delta. In particular, the simultaneous measurement of nutrients, organic matter and algal abundance along with the basic water quality variables such as temperature and salinity -...