Tidal marshes are important ecosystems in the San Francisco-Bay Delta. They remove carbon from the atmosphere, build up soils that buffer our communities from sea level rise, mitigate excessive nutrients (like nitrogen), and provide critical habitat and food resources for a diversity of species. It is difficult to predict how tidal marshes change naturally over time versus as a response to climate change, restoration and water quality changes. This project provides the first ever multi-year dataset of the complete carbon budget of a tidal marsh. This dataset will be used to predict seasonal and annual carbon budgets in tidal marshes over a range of salinities. The model will assess the sustainability of existing and potential restored tidal wetland benefits over the next 100 years using remote sensing data. The model will be an open-source tool designed for use by wetland managers and decision makers in the Bay-Delta region. This project supports ongoing initiatives to restore tidal wetlands in the Delta and our ability to manage them in a changing world.
This study combines detailed model predictions with salmonid tracking data to inform how river flows affect steelhead movement through the Delta. This project leverages an existing 6-year data set to support analysis of salmonid behavioral responses across a broad range of water years. The study will evaluate behavior relative to flow under existing regulatory requirements (Old and Middle River Flow and the Inflow to Export ratio), evaluate five new potential water management metrics identified by the Collaborative Adaptive Management Team Salmonid Scoping Team, and improve the understanding of what conditions affect survival.
This project aims to quantify the impacts of common reed (Phragmites) invasion on community structure and ecosystem function during early stages of tidal restoration in wetlands. The study will focus on the Tule Red Tidal Restoration site in Suisun Marsh. The research aims to produce a conceptual model that will describe habitat structure, invertebrate communities, and predator use of wetlands affected by Phragmites invasion. The conceptual model resulting from this study will guide future predictions of wetland response to invasion and to develop mitigation strategies. Data collected will also support food web models and the understanding of invasive plants as stressors, as well as foster translational science to the management community.
This project aims to improve understanding of atmospheric and hydrologic carbon fluxes in a restored tidal salt marsh in the South San Francisco Bay. I will use soil chambers to measure how much carbon dioxide and methane is taken in and emitted from the marsh. The project will also examine how spatial variability in marsh surface cover impact these exchanges. Shahan will use the data collected in this study to create a biogeochemical model that estimates the carbon budgets of wetlands in the Bay-Delta. A complete carbon budget will illuminate relationships between carbon fluxes and environmental variables. This information can support more informed management of wetlands, as well as allow researchers and decision makers to more effectively plan wetland restoration to be effective in managing carbon fluxes in the face of possible impacts due to climate change.
This project aims to characterize and quantify where detrital material (decaying plant matter) originates within wetlands, the composition of that material, and how export of detrital particles occurs. This project will combine powerful characterization tools and techniques that scale from molecules to ecosystems to assess spatial and temporal trends in particle sources, species and composition. Because restoration in the Sacramento-San Joaquin Delta will fundamentally alter particle distribution and food availability for aquatic organisms, this study will inform habitat restoration efforts and the revival of native fish populations. The tools developed and adapted for this project may inform management response during extreme conditions and climate events by helping to identify areas that may act as refugia for species.
This is a continuation of a five-year project funded by CDWR and CDFW and the Central Valley Project Improvement Act in 2017. The objective of the project is to improve estimates of population abundances for fall, winter and spring run juvenile Chinook Salmon at Sacramento and Chipps Island by improving trawl efficiency estimates using data from releases of coded wire tags (CWT), acoustic tags (AT), and by genetically sampling the trawl catch in 2025 and 2026. The project will (1) develop statistical models for estimating trawl efficiencies using 2016-2025 data for paired AT-CWT releases of winter run and fall-run Chinook Salmon; (2) use 2016-2025 genetic sampling of trawl catch in combination with efficiency estimates to estimate population abundances of fall, spring and winter run at Sacramento and Chipps Island for 2016-2025; (3) implement trawl efficiency studies for multiple salmon runs in 2025-2026 informed by the prior results and in coordination with hatcheries for inclusion of AT fish with existing CWT releases; and (4) combine trawl efficiencies with genetic samples of trawl catch to provide estimates of fall, spring and winter-run salmon abundance (with estimated precision) entering and exiting the Delta in 2016-2025.
The overarching AIS goal is that "Risks of aquatic invasive species invasions are substantially reduced, and their economic, ecological, and human health impacts are minimized. This goal is addressed through a series of performance and workload measures. The AIS Program provides funding for Aquatic Invasive Species Coordinators for each Region within the Service and their respective aquatic nuisance species activities. These coordinators work closely with the public and private sector to develop and implement invasive species projects. One of the primary initiatives of the program is the prevention of invasive species via boats through the "100th Meridian Initiative" (overseen by individual AIS regional coordinators). This initiative aims to prevent the spread of aquatic invasive species by boats personal watercraft and other pathways. Through boat inspections and boaters assessments along the 100th meridian, partners can learn how to prevent the spread of zebra mussels and other AIS via transport of boats and personal watercraft.
The Sacramento-San Joaquin Delta is a highly altered and impaired ecosystem that is critical to the freshwater infrastructure of the State of California. Salt intrusion from San Francisco Bay into the Delta, however, threatens freshwater delivery to the southern portions of the state and so management and restoration actions within the Bay-Delta must continuously balance both ecosystem and operational needs. While previous numerical modeling studies have sought to examine changes in the estuarine physics of the system, these tools are costly to develop and run. Thus there is a need to develop alternate methods for monitoring the movement of water through the Bay-Delta, as proposed here. The proposed research project approaches tracking the mixing between the Bay and Delta waters through the novel use of daily satellite color imagery. These findings will be linked to in situ measurements throughout the system and used to inform relevant agencies of flow characteristics within the waterways. This work is motivated by a need for high frequency monitoring of finescale features within the dynamic Bay-Delta ecosystem and to take advantage of new advanced remote sensing technology to inform on long-term trends within the Delta.
The primary objectives of this research are to: 1. Enhance monitoring programs to inform management in the presence of climate change and additional stressors, 2. Inform on ecosystem resilience to interannual hydrologic variations and climate change impacts, and 3. Evaluate how climate change and flow regime changes will impact water quality in the Delta.
Water primrose (Ludwigia spp.) is a highly invasive, non-native floating macrophyte in the Delta. In recent years, water primrose has extended its niche into marsh habitat, causing extensive mortality of marsh macrophytes including tules and cattails. The goal of this project is to determine whether the growth strategy of water primrose, its allelopathic properties, or factors related to plant community structure are the cause of marsh loss following water primrose invasion in the Delta. Part of this study will identify and map the marshes most vulnerable to loss and quantify the spatial trajectory of marsh loss during the past 15 years. The ultimate benefit will be an improved understanding of the water primrose invasion processes in the Delta, which can be used to prioritize herbicide treatment of this highly invasive plant in marshes most vulnerable to invasion and with the highest habitat value.
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