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.
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.
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.
