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 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.
The National Wetland Condition Assessment (NWCA) is a statistical survey that begins to address some of the gaps in our understanding of wetland health by providing information on the ecological condition of the nation's wetlands and stressors most commonly associated with poor condition. The NWCA is designed to answer basic questions about the extent to which our nation's wetlands support healthy ecological conditions and the prevalence of key stressors at the national and regional scale. It is intended to complement and build upon the achievements of the U.S. Fish and Wildlife Service Wetland Status and Trends Program, which characterizes changes in wetland acreage across the conterminous United States. Paired together, these two efforts provide government agencies, wetland scientists, and the public with comparable, scientifically defensible information documenting the current status and, ultimately, trends in both wetland quantity (i.e., area) and quality (i.e., ecological condition).
A team at UC Davis (Dr. Mark Lubell, Dr. Gwen Arnold, PhD Candidate Kyra Gmoser-Daskalakis) is conducting social science research on wetland restoration in the California Bay-Delta as part of a larger, interdisciplinary project on wetland restoration across multiple University of California campuses and national labs ("Coastal Wetland Restoration a Nature Based Decarbonization Multi-Benefit Climate Mitigation Solution"). First, the project is conducting social network and spatial analysis using the EcoAtlas project database to examine drivers of wetland restoration investment in the Bay-Delta from the 1980s to now. Second, case studies of individual restoration projects and interviews with 40+ restoration project partners examines barriers to the restoration implementation and perceptions and goals of multi-benefits among interested parties. Preliminary results have been shared at the State of the Estuary and Bay-Delta Science Conferences in 2024. See https://wetlands.ucsc.edu/index.html for more information.
To support management planning in Suisun Marsh, this project is developing a body of science and tools to understand past, present, and potential future changes to the Marsh’s ecological patterns, processes, and functions. This project builds on SFEI’s prior work in the Delta, extending historical ecology mapping, landscape change studies, and the Landscape Scenario Planning Tool to cover Suisun's historical and present-day landscapes. Through spatially explicit representations of the historical function and condition of the marsh and analyses of landscape metrics, this project is evaluating changes over time in landscape support for ecosystem functions and services in Suisun. In order to incorporate diverse perspectives into planning resources, project activities include engagement with local tribes and community members to understand community interests, priorities, and uses of the Marsh. Findings will be shared through a report and article for both technical and general audiences, and spatial analyses and data layers will be made available through the Landscape Scenario Planning Tool.
Assessing the success of tidal marsh restoration is a top priority for coastal managers across the US. Estuarine habitat restoration has been prioritized due to the importance of the ecosystem functions (Callaway et al. 2012) and services (Costanza et al. 2014) they provide and the threats to them by climate driven sea-level rise (hereafter SLR; Craft et al. 2009, Donnelly & Bertness 2001, Schile et al. 2014) and other stressors (Mariotti & Fagharazzi 2013). Given the importance of management for estuarine habitats to survive SLR (Kirwan & Megonigal 2013) and the importance of public responses to approve and fund restoration projects, it is critical to understand how to broadly assess the success of restoration from the perspectives of both ecological performance and public perceptions. However, the San Francisco Estuary (SF Estuary), stretching from the Lower San Francisco Bay through Suisun Marsh to the Sacramento-San Joaquin Delta, encapsulates diverse social and environmental dynamics (Moyle et al. 2014) and varying perceptions by sociodemographic group (Rudnick et al 2022). Our project is focused on the Suisun Marsh and Delta and seeks to understand these complexities by integrating social, environmental, and management perspectives.
The Wetland Regional Monitoring Program (WRMP) Fish and Fish Habitat Monitoring project is a collaborative effort to track biological responses to tidal wetland restoration in the San Francisco Estuary. Monthly sampling is conducted across a network of benchmark, reference, and project restoration sites in the South Bay and North Bay, with the goal of evaluating how wetland restoration influences fish assemblages, habitat use, and ecological condition.
The study uses primarily otter trawls to monitor fish and macroinvertebrate communities. Standardized field methods align with those used in long-term monitoring programs to ensure comparability and data integration across regions. Environmental data, including water temperature, salinity, and dissolved oxygen, are collected in tandem with biological sampling to assess habitat quality and seasonal dynamics.
The program addresses WRMP Guiding Question #4: How do policies, programs, and projects to protect and restore tidal marshes affect the distribution, abundance, and health of fish and wildlife? The data support adaptive management, regulatory compliance, and science-based restoration planning by identifying key habitats, tracking restoration performance, and detecting regional patterns in species composition and abundance over time.
Invasive aquatic vegetation (IAV) is a threat to aquatic ecosystems worldwide, leading to a major loss of biodiversity and extensive damages and costs to human uses of those ecosystems. The Sacramento-San Joaquin River Delta (the “Delta”) is the hub of California’s water system, supporting over 35 million water users and a $54 billion agricultural industry. The Delta reform act mandates management decisions meet both water supply needs while maintaining the ecological function of the system. The Delta is a global biodiversity hotspot, and the focal point of $750-$950 million in restoration. It has also been called one of the most invaded estuaries in the world. Over the past 15 years, submerged and floating IAV have more than doubled in extent, threatening water supply and ecosystem health of the Delta. There is mounting evidence that herbicide treatments are not effective, and that water management actions, and wetland restoration may be having huge impacts on IAV. This presents both a risk to increasing IAV, but also an opportunity to prevent and even effectively combat IAV through considered water management actions and better restoration planning, meeting the state’s co-equal goals of water security and Delta ecosystem conservation.
This project will meet the needs of multiple state agencies by advancing operational Earth observation-based monitoring program for community-level submerged aquatic vegetation (SAV) and genus-level floating aquatic vegetation (FAV) and modeling tools to enable the Delta management community to assess the effect of previous management actions on IAV and forecast the effects of future actions to inform multi-agency decision making. Specifically, this work will 1) Operationalize IAV class mapping using Sentinel-2 satellite imagery, 2) Finalize and validate species distribution Models (SDM) for SAV community and FAV at genus-level to assess the impacts of previous water actions on IAV and predict IAV distribution in future scenarios, 3) Co-design IAV-based performance metrics to inform future actions.
The proposed project fills a critical data gap in monitoring for state and federal agencies and stakeholders by implementing the first sustainable mapping effort for IAV. Monthly and seasonal estimates of SAV and FAV coverage will enable the Delta Stewardship Council to improve their performance metrics for evaluation of the Delta Plan and will help the Interagency Ecological Program assess whether management is meeting the co-equal goals for the Delta. Species distribution models will enable Department of Water Resources to evaluate how previous restoration flow actions have affected the spread and persistence of IAV and incorporate what they learn into future Structured Decision Making to better account for negative consequences of IAV when setting future restoration targets and implementing actions.
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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