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  • Title

    Habitat, hatcheries, and nonnative predators interact to affect juvenile salmon behavior and survival

    Lead University of California - Santa Cruz [UCSC]
    Description Chinook salmon are an iconic part of California’s environment and heritage, and important both economically and culturally. In the Sacramento River, the winter-run Chinook population is endangered, and there is strong interest in restoring these populations. To do so, resource managers need to better understand the pressures on wild populations. Predation by nonnative predators affects survival of young salmon but may also affect the behavior of salmon. Changes to salmon behavior also have costs but are not currently considered in management. Managers need information on how predators affect juvenile salmon behavior, how they might vary under different conditions, and how they scale up to affect populations.
    Science topics Chinook Salmon, Fishing
    Updated November 17, 2022
  • Title

    Do light, nutrient, and salinity interactions drive the “bad Suisun” phenomenon? A physiological assessment of biological hotspots in the San Francisco Bay-Delta

    Lead University of California - Santa Cruz [UCSC]
    Description This project assessed the physiological basis for reduced phytoplankton growth in Suisun Bay, prior to the major upgrade at the Sacramento Regional Wastewater Treatment Plant (SRWTP), which is responsible for 90% of the nitrogen released into the bay. The work involved analyzing almost three decades of historical eld data from the bay-delta and using it to build a model to evaluate environmental drivers of phytoplankton biomass. Discoveries from the eld data were then tested through laboratory culturing experiments. By illuminating the interacting e ects of bottom- up drivers (light, nutrients, salinity) on phytoplankton, this research helps provide a fundamental understanding of this complex ecosystem.
    Science topics Ammonia, Flushing rates, Light, Open water, Pelagic fish, Phytoplankton, Salinity, Wastewater discharge, Water temperature
    Updated November 17, 2022
  • Title

    A Next-generation Model of Juvenile Salmon Migration through the Sacramento-San Joaquin Delta

    Lead University of California - Santa Cruz [UCSC]
    Description While migrating through the Delta and its tributaries, Chinook salmon and steelhead move through diverse habitats, encounter predators, interact with highly dynamic flows, and are impacted by a multitude of human-made structures. Funding for this Project will be use to develop integrated system-level models that will effectively manage salmonid populations and other key resources in the California Central Valley.
    Science topics Salmon migration
    Updated November 18, 2022
  • Title

    Life History Variation in Steelhead Trout and the Implications for Water Management

    Lead University of California - Santa Cruz [UCSC]
    Description The purpose of this project is to explore the ways in which different stream hydrology and temperature can affect the growth and maturation of steelhead trout. Model examination will incude various stream flow management regimes may affect trout population dynamics region-wide.
    Science topics Steelhead Trout
    Updated April 29, 2022
  • Title

    Improving Green Sturgeon Population and Migration Monitoring

    Lead University of California - Santa Cruz [UCSC]
    Description Green sturgeon is a listed species under the federal Endangered Species Act. This project supports the recovery and management of the southern distinct population segment of green sturgeon by improving population and migration monitoring. Improved monitoring is recommended in multiple initiatives to help protect this species, such as the Green Sturgeon Recovery Plan. There is some uncertainty on whether the most appropriate green sturgeon monitoring techniques are being used. This project compares the different estimation and monitoring techniques to identify the superior protocol. To compare the effectiveness of different techniques, scientists will monitor green sturgeon in the Sacramento River using sonar technology. Monitoring data will be used to estimate the population size and death rates due to by-catch. This project will also review and synthesize past acoustic telemetry data to determine if the data can be modeled to improve population size estimates.
    Science topics Green sturgeon
    Updated June 3, 2024
  • Title

    Using existing datasets to understand multi-scale changes in and controls on biogeochemistry in the SF Bay-Delta

    Lead University of California - Santa Cruz [UCSC]
    Description In collaboration with the United States Geological Survey, this research will explore temporal and spatial variability of carbon and nitrogen biogeochemistry across the San Francisco Bay-Delta. This science synthesis will capitalize on existing multi-year isotope datasets to gain new insights useful for understanding future changes in the system. The results generated from this two-year data synthesis project will be useful for improving our current understanding of factors driving changes in SF Bay-Delta biogeochemical processes. Results will also be informative for understanding the imminent changes coming to the from the Sacramento Regional Wastewater Treatment Plant upgrade.
    Science topics Nitrogen
    Updated February 27, 2025
  • Title

    Functional diversity and predator dynamics along the Sacramento and San Joaquin River Delta

    Lead University of California - Santa Cruz [UCSC]
    Description This project's objectives are to: 1) determine snake species diversity and relative abundance, 2) establish resources available and examine the functional role that snakes play along field sites within the Sacramento-San Joaquin River Delta, 3) document predator-prey interactions, and 4) assess the thermal physiology of snakes and the thermal profile of microhabitats along the Sacramento-San Joaquin Delta.
    Science topics Habitat, Invasive / non native species
    Updated February 27, 2025
  • Title

    Perceptions of risk and management of the Delta levee system

    Lead University of California - Santa Cruz [UCSC]
    Description This study of the perceptions of flood risk and management of the levee system in a deltaic region of California illuminates the social, cultural, and psychological complexities of risk assessment. In order to better understand risk tolerance, we included stakeholders from the following groups: agriculture, engineering, boating and recreation industry, local reclamation districts, conservation organizations, water exporters, county government, and state agencies. Methods employed are qualitative and quantitative and include interviews and media analysis. For decades the Sacramento-San Joaquin Delta has been ripe with political controversies stemming from conflicting interests for its natural resources. The results of this study reveal distinct views on the sustainability of the Delta’s levees, the resilience of local communities, and who is accountable for present conditions. The findings of this study also elucidate nuances in the conversations on the viability of mitigation and adaptation as conditions in the Delta change. We conducted this study in two parts. First, we used the Q methodology and found five distinct views that shape stakeholders’ perceptions of risk of flooding from levee failure: fatalistic, skeptical, free market, bio-centric, and human ingenuity. Second, we collected over 500 newspaper articles from 1986 to 2017 to analyze the framing of issue of flooding in the Delta. As opposed to our study with diverse stakeholders, our media analysis show that the issue of flood risk has been framed in the media mostly along the binary lines of unpreventable catastrophe and control through emergency management.
    Science topics Levees
    Updated January 23, 2024
  • Title

    Source characterization and biogeochemical consequences of wastewater and agricultural C, N, and P inputs to the Sacramento-San Joaquin Delta region.

    Lead University of California - Santa Cruz [UCSC]
    Description This project aimed to characterize the sources of carbon, nitrogen, phosphorous and sulfur compounds from wastewater treatment plant and agricultural discharge in the region. Stable isotope measurement provides elemental signatures that can be used to trace compounds to their sources. Use of this methodology requires that researchers first characterize the stable isotope composition of sources—or fingerprint the suspects. By determining the stable isotope composition of various compounds in wastewater and agricultural drainage sources, this project aimed to build a better understanding of how these compounds are affected by different wastewater treatment agricultural land use practices. In addition, the project has provided a base of knowledge to better understand how these compounds are transported and taken up in the delta environment.
    Science topics Carbon, Nitrogen, Phosphorous, Wastewater discharge
    Updated February 26, 2024
  • Title

    High-Frequency Monitoring of Delta Island Drainage Waters to inform carbon budgets and contaminant export

    Lead University of California - Santa Cruz [UCSC]
    Description This Proposition 1 funded study aims to use high-frequency measurements and paired grab samples to document water quality and carbon exports in relation to land use change on Delta Islands. The project involves monitoring one station on Twitchell Island and two on Staten Island.
    Science topics Landscape change
    Updated August 25, 2024
  • Title

    FutureTracts: Leveraging Agent-Based Models to Forecast Land Use Changes in California's Central Valley

    Lead University of California - Santa Cruz [UCSC]
    Description

    The proposed project is driven by the need to understand how land use has changed historically in California's Central Valley due to various drivers including environmental changes and socio-economic developments. Given the region's dependency on agriculture and its vulnerability to climate change—marked by shifts in precipitation patterns and water availability—it's crucial to model these dynamics accurately to forecast future conditions and plan effectively. Using Agent-Based Modeling (ABM) provides a sophisticated means to dissect past interactions between land use and environmental factors at a granular level. This historical understanding is pivotal as it sets the stage for projecting future scenarios. Additionally, the integration of future hydrology data generated from the CalSim3 model and socio-economic scenarios allows for a comprehensive analysis of potential future states. This analysis aims to explore strategic land use modifications that can meet future socio-economic goals under varying water availability scenarios. 

    This research supports several key science actions, making it highly relevant to current policy discussions. It provides actionable insights into large-scale experiments (Science Action 1C), assesses the impact of climate on ecosystems (Science Action 6A), and explores water allocation strategies (Science Action 6E), thereby equipping policymakers and stakeholders with the necessary tools for informed decision-making. These decisions are crucial for maintaining ecological flows and ensuring the longterm viability of both the agricultural sector and the natural ecosystems upon which they depend.
    Science topics None specified
    Updated March 11, 2025
  • Title

    The effects of climate change on the life history of spring-run Chinook Salmon through time

    Lead University of California - Santa Cruz [UCSC]
    Description

    Chinook Salmon (Oncorhynchus tshawytscha) populations in California are in decline due to the combined effects of habitat degradation, water diversions, and shifting climate regimes. This project uses archival tissues (otoliths, vertebrae) from modern and ancient spring-run Chinook Salmon to understand how shifts in migration timing and habitat use allowed salmon to cope with highly variable environmental conditions. We will learn how salmon responded to the recent drought and flood periods (2012-2020 CE), the California Gold Rush Period (~1835-1870 CE), the Little Ice Age (~1560-1780 CE), and the Megadrought Period (~1200-1410 CE). This effort will provide the insights needed for developing climate-adapted conservation actions to support salmon into the future.
    Science topics Chemistry, Chinook Salmon, Climate change, Environmental drivers, Fish, Habitat, Salmon rearing
    Updated April 8, 2025