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  • Title

    The value of information is context dependent: a demonstration of decision tools to address multi-species river temperature management under uncertainty

    Lead CALFED Bay-Delta Program
    Description

    Tradeoffs among objectives in natural resource management can be exacerbated in altered ecosystems and when there is uncertainty in predicted management outcomes. Multicriteria decision analysis (MCDA) and value of information (VOI) are underutilized decision tools that can assist fisheries managers in handling tradeoffs and evaluating the importance of uncertainty. We demonstrate the use of these tools using a case study in the Sacramento River, California, U.S.A., where two imperiled species with different temperature requirements, winter-run Chinook Salmon (Oncorhynchus tshawytscha) and Green Sturgeon (Acipenser medirostris), spawn and rear in the artificially cold Shasta Dam tailwater. A temperature-control device installed on Shasta Dam maintains cool water for Chinook Salmon; however, uncertainties exist related to the effects of temperatures on the spawning and rearing of both species. We consider four alternative hypotheses in models of early life-stage dynamics to evaluate the effects of alternative temperature-management strategies on Chinook Salmon and Green Sturgeon management objectives. We used VOI to quantify the increase in management performance that can be expected by resolving hypothesis-based uncertainties as a function of the weight assigned to species-specific objectives. We found the decision was hindered by uncertainty; the best performing alternative depends on which hypothesis is true, with warmer or cooler alternative management strategies recommended when weights favor Green Sturgeon or Chinook Salmon objectives, respectively. The value of reducing uncertainty was highest when Green Sturgeon was slightly favored, highlighting the interaction between scientific uncertainty and decision makers’ values. Our demonstration features MCDA and VOI as transparent, deliberative tools that can assist fisheries managers in confronting value conflicts, prioritizing resolution of uncertainty, and optimally managing aquatic ecosystems.

    Science topics Chinook Salmon, Fish, Flows, Green sturgeon, Salmon rearing, Sturgeon, Temperature, Water conveyance / infrastructure, Water temperature
    Updated October 10, 2024
  • Title

    Addressing CyanoHABs as a Threat to Water and Air Quality in the San Francisco Bay-Delta

    Lead University of California - Santa Cruz [UCSC]
    Description

    The Sacramento-San Joaquin Delta (Delta) faces a serious threat from the recent proliferation of cyanobacterial harmful algal blooms (cyanoHABs), particularly due to the production of high levels of cyanobacterial toxins. These blooms jeopardize water quality and pose a significant risk to air quality when toxins are released as particles in a process known as aerosolization. When people inhale these aerosols, it can trigger an inflammatory response, yet the specific form in which toxins are aerosolized remains unknown. Thus, an improved understanding of cyanobacterial toxin aerosolization mechanisms has significant human health implications. To assess the public health risks associated with airborne cyanobacterial toxins, the project examined the size distribution of cyanoHAB aerosols and the factors influencing their aerosolization. They also investigated the role of nutrient enrichment in cyanoHAB growth, cyanobacterial toxin production, and cyanotoxin aerosolization through a combination of laboratory and field experiments.

    Project Objectives

    1. Investigate and quantify the production of primary spray aerosols during cyanoHABs

    2. Assess the linkage of nutrient enrichment, phytoplankton community composition, toxin production, and cyanoHAB aerosol formation

    This project addresses a pressing environmental and public health concern. The data can be used to protect vulnerable communities living near affected bodies of water and inform ways to mitigate the adverse impacts of cyanoHABs on the Delta’s environmental and public health.

    This research improves Delta-specific human exposure guidelines to cyanoHAB aerosols by providing data essential for implementing effective public health measures, including recommendations on mask usage and understanding the expected way aerosols travel through the air from the shoreline. Their investigation into the relationship between nutrient availability, cyanoHABs growth dynamics, toxin production, and aerosol formation will offer valuable insights for management efforts aimed at regulating algal blooms to improve both water and air quality outcomes. Ultimately, this research will strengthen state agency responses to human illness associated with cyanoHABs and toxin exposure.

    Science topics Harmful algal blooms HAB
    Updated July 24, 2025