Aquatic Ecosystems

The Sacramento-San Joaquin Delta (Delta) supplies drinking water to much of California. The Delta also provides irrigation water to the Central Valley and is an important habitat to many aquatic and terrestrial species. In the past decade, there has been an increase in harmful algal blooms (HABs) in the Delta. While some HABs are nontoxic, others contain cyanobacteria that can produce dangerous...

The effect of selenium toxicity on wildlife has been known for more than 50 years. This issue drew particular attention in the 1980s when embryo deformity and mortality was observed in birds at a wildlife refuge in California. Harmful effects from selenium were determined to be connected to irrigation drainage water. As a result, an effort began to monitor levels of selenium in irrigation drainage...

Drought is making the Delta Saltier. Less freshwater coming from watershed runoff and reservoir releases means that more salty water flows into the Sacramento San Joaquin Delta (Delta) from the Pacific Ocean. Changes in Delta salinity have far-reaching impacts, affecting the water supply for agriculture, drinking, wildlife, and Delta ecosystems.

The USGS California Water Science Center conducts a variety of research activities at Clear Lake, California, including surface-water monitoring and water quality and aquatic habitat studies.

The Clear Lake Hitch ( Lavinia exilicauda chi ) population, which once flourished in great abundance, has been decimated by loss of spawning habitat, nursery areas, and the encroachment of non-native species. In order to make an informed decision, the California Water Science Center has been asked by the U.S. Fish and Wildlife Service to conduct studies into the fish’s habitat, specifically...

The USGS is collecting continuous and discrete monitoring data to document baseline conditions and physical responses in downstream river reaches before, during, and after dam removal. These monitoring data will be integral for post-removal assessments and collaborations with basin partners.

Blue carbon ecosystems (BCEs) are coastal ecosystems, such as tidal marshes, mangroves, and seagrasses, with manageable and atmospherically significant carbon stocks and fluxes. The tidal marshes and scrub-shrub wetlands in the Sacramento-San Joaquin Delta (Delta) of California are examples of BCEs. The Delta is a 2,400 square kilometer tidal freshwater region located at the landward end of the...

Wetland restoration on Moloka'i is needed to expand habitat for endangered species, improve ecosystem services, increase access to cultural resources including sedges for weaving, and increase opportunities for growing taro. The goal of this project is to assess the current status of wetlands on the island of Moloka‘i, evaluate potential impacts of projected sea level rise on these habitats, and...

Microcystins are toxins produced by cyanobacteria (previously known as blue-green algae ) that are harmful to humans and other animals. In 2012, microcystins began to be detected in San Francisco Bay (SFB). This was unexpected because most microcystin producing cyanobacteria live in freshwater. On-going microcystin-related work has focused on monitoring the presence of microcystins in water and...

The California Water Science Center's Aquatic Ecology Group is making great strides in research and reporting.

Coastal vegetated habitats, such as tidal wetlands, play an active role in the global carbon cycle. This is done through the removal of CO2 by living vegetation through photosynthesis and by the decay of organic matter and its burial for hundreds to thousands of years.

To help the U.S. Bureau of Land Management determine the long-term sustainability of the San Sebastian Marsh, and its critical role for the survival of the endangered desert pupfish ( Cyprinodon macularius ), the USGS is evaluating the potential interactions and relation between groundwater and surface water at the San Sebastian Marsh.