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IEP Calendar

Check out the IEP Calendar for upcoming Project Work Team, Stakeholder Group meetings and other IEP related events!

  • August 29 Zooplankton Project Work Team Meeting 10:00 a.m. - 12:00 p.m.

Other Events or News

  • San Francisco Estuary Partnership (SFEP) launches Estuary Youth Council
    • In 2023, the SFEP kicked off a new youth-centered program called the Estuary Youth Council. This is a pilot leadership development program developed in collaboration with Mycelium Youth Network, Nuestra Casa, and Restore the Delta. The Estuary Youth Council will give young people, especially youth from underserved communities, opportunities to advise environmental managers with youth-centered perspectives, priorities, and concerns in the restoration and adaptation of the San Francisco Estuary as well as offer professional development.
  • Got something new to share? Contact us at iep@wildlife.ca.gov.

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Featured Survey

  • Summer Townet Survey
    The Summer Townet Survey (STN) is one of the longest running long-term fish monitoring programs. Since 1959, STN has sampled fixed locations from eastern San Pablo Bay to Rio Vista on the Sacramento River, and to Stockton on the San Joaquin River and a single station in the lower Napa River. The survey was initially started to monitor age-0 Striped Bass (Morone saxatilis) and later began to monitor Delta Smelt (Hypomesus transpacificus), a sensitive native species believed responsive to the proper functioning of the Delta region. Data collected at 31 index stations are used to calculate annual relative abundance indices for age-0 Striped Bass and Delta Smelt. The study area was expanded in 2011 to include stations located within the Sacramento Deep Water Ship Chanel and Cache Slough for a total of 40 stations. These stations are sampled every other week June through August.

    In addition to fish, the STN also measures environmental variables including water temperature (°C), water clarity (Secchi Depth & NTU) and specific conductivity (µS/cm). Managers and researchers use the data collected by STN to monitor long-term trends in the fish and invertebrate community, monitor the diet and condition of important predator and prey fish species, detect the introduction of new and potentially invasive species, inform decisions and improve the understanding of the health of the San Francisco Estuary.

    Additional information on abundance indices, sampling protocol, and copies of the STN databases can be found on the CDFW FTP site for the Fall Midwater Trawl. The FMWT and STN data are stored in the same FTP site.

Featured Publications

  • From an impressive list of coauthors led by Ed Gross (on behalf of 6 collaborators) published in Estuaries and Coasts as Estimating biogeochemical rates using a computationally efficient Lagrangian approach: “Numerous biogeochemical and physical processes in estuaries influence nutrient concentrations during transport, resulting in complex spatial and temporal variability and challenges identifying predominant processes and their rates… We developed a modeling approach that decouples transport from transformations, enabling fast, data-driven exploration of the parameter space.” The authors conclude: “The model performed each simulation in milliseconds on a laptop computer, allowing the fitting of rate parameters for key transformations by optimization. The optimization used fixed station nitrate observations and the model was then validated against high-resolution mapping observations of ammonium and nitrate. The results suggest that the observed spatial and temporal variation can be largely represented with five transformation processes and their associated rates. Dissolved inorganic nitrogen (DIN) losses occurred only in shallow vegetated areas in the model, highlighting that biogeochemical processes in these areas should be included in DIN models.”
  • In an important research article from Restoration Ecology using oysters as a focus species, Zabin and teammates posit some non-traditional criteria for understanding successful regional restoration efforts. The article, The portfolio approach: a way forward for restoration of native Olympia oysters in a dynamics urban estuary, has important implications for designing restoration efforts in the San Francisco Bay Estuary. “Our results, combined with data from natural populations at multiple sites, suggest that restoration outcomes within SFB could be improved by building and strengthening a connected portfolio of sites that are not simultaneously exposed to the same stressors. We recommend siting restoration projects across locations that represent a range of environmental conditions but that are sufficiently close for larval exchange. Unlike typical restoration approaches that use site selection to identify the best locations, the portfolio approach, just like the economic investment principle, would employ a diversity of environmental conditions. Because these environmental conditions can change over time, this approach can reap the greatest rewards over the long run precisely because of that diversity.”
  • Preece, Otten, and Cooke, in the Marine Pollution Bulletin, have published Use of multiple sampling techniques for cyanobacteria and cyanotoxin monitoring in the Sacramento-San Joaquin Delta under different hydrologic regimes. Their research highlights variable results regarding techniques for tracking microcystins, and the need to pursue several complementary methods to do so. From their abstract: “Cyanobacteria harmful algal blooms (CHABs) are a growing water quality problem in the upper San Francisco Estuary (California), also known as the Sacramento-San Joaquin Delta. We conducted cyanobacteria and cyanotoxin monitoring from 2020 to 2023, which spanned California’s driest consecutive 3-year period and one of the wettest years on record (2023). To assess the impact of CHABs over this range of hydrologic conditions, we monitored invasive Asian Clams (Corbicula fluminea) for microcystin contamination and used molecular tools (qPCR and sequencing) to characterize cyanobacteria in the water column. We also used solid phase adsorption toxin tracking (SPATT) samplers to track microcystins (MCs) and other cyanotoxins in 2023.”
  • In the first of five articles (!) from the most recent issue of the San Francisco Estuary and Watershed Science journal Vaughn and 10 co-authors share their research in an article titled: Managed Wetlands for Climate Action: Potential Greenhouse Gas and Subsidence Mitigation in the Sacramento–San Joaquin Delta. In the article the authors quantify and discuss the potential benefits and trade-offs of using wetlands to mitigate the effects of greenhouse gas emissions and land subsidence in the Delta. They discuss how “Large-scale wetland restoration and conversion to rice fields has the potential to mitigate these effects while conferring flood protection and creating habitat for wetland species. To explore the scale of these potential benefits, this study evaluated the effects of seven Delta-wide land-use scenarios on carbon stocks, land-surface elevation, GHG emissions, and habitat.”
  • Huntsman and an impressive list of co-authors have published Climate Change Scenarios for Air and Water Temperatures in the Upper San Francisco Estuary: Implications for Thermal Regimes and Delta Smelt. In this work, the collaborators: “assessed downscaled air temperature data from 10 global climate models (GCMs) under two representative concentration pathway (RCP) trajectories for greenhouse gas concentrations for three regions of the San Francisco Estuary: Sacramento–San Joaquin Delta, Suisun and Grizzly bays, and Suisun Marsh… Our results suggested there were no major differences in the extent of air temperature warming among the three regions. Annual average air temperatures were projected to increase approximately 2.0 °C and 4.7 °C by the end of the century for the low and high RCP scenarios, respectively.”
  • The complicated subject of contaminant effects on Delta Smelt is the subject of a research article (Sub-Lethal Responses of Delta Smelt to Contaminants Under Different Flow Conditions) from Stillway and colleagues, also from the most recent San Francisco Estuary and Watershed Science volume. The authors “examine the association between contaminants and Delta Smelt health across contrasting water year types and flow-related management actions.” They ultimately conclude that: “Insecticides, particularly fipronil metabolites, were the most prevalent contaminants detected in 2017 and 2018, and a variety of contaminants associated with the rice harvest were detected in 2019. No acute toxicity was observed during any exposure, but we observed negative effects in the livers of Delta Smelt exposed to agricultural water from the Toe Drain and Cache Slough during a 2019 pulse flow action, which coincided with elevated detections and concentrations of organic pesticides.”
  • California statewide water use is characterized in this new and important policy-related article from John Helly and collaborators. In another article from the SFEWS journal Spatial patterns of water supply and use in California explores how “Spatial and temporal patterns of water supply and consumptive water use were analyzed from 475 Detailed Analysis Units by County (DAUCOs) spatial units across California during 2002 through 2016 to evaluate spatial and temporal variability and how it might associate with precipitation variability and other factors… An important result for planners is our finding that variation in precipitation—itself important—is amplified by the human response to water supply availability and regulatory policy.”
  • Biotic homogenization is the subject of a research article in the San Francisco Estuary and Watershed Science journal from McKenzie and co-authors titled Regional diversity trends of nearshore fish assemblages of the upper San Francisco Estuary. From their abstract: “In this study, we used data from a long-term beach seine survey to analyze regional beta diversity trends of nearshore fish assemblages in the Delta from 1995 to 2019. Overall, we found no evidence of regional biotic homogenization occurring over the study period. Regional beta diversity increased moderately over time and was significantly influenced by the high interannual variability of freshwater inflow.”
  • Bowen and 10 colleagues explored the use of different techniques for eDNA sampling when detecting the presence of longfin smelt in wetlands within the Estuary (restored and otherwise). Their article: A comparison of eDNA sampling methods in an estuarine environment on presence of longfin smelt (Spirinchus thaleichthys) and fish community composition appears in a recent volume of Environmental DNA. From the abstract, “The loss of tidal wetlands in the San Francisco Bay estuary have led to declines in native fish presence. Restoration of tidal wetlands in this area has intensified, with a primary goal of increasing the number of native fishes. We compared the presence of longfin smelt in naturally accreted and beneficial dredge reuse wetlands as a measure of successful restoration. We used environmental DNA (eDNA) analyses as our metric for fish presence and fish community composition, employing two different water sampling methods for comparison (standard and high-volume). Longfin smelt were present in multiple sites, but at numbers too low for accurate comparisons across sites.”
  • Evaluating the impact of captive ancestry on the growth and survival of Delta Smelt in a captive environment is the title of an article in the most recent edition of Aquaculture Reports. Chase and others from UC Davis, CDWR, and USFWS report “We conducted a study over two consecutive years to investigate the effects of varying levels of captive ancestry on the growth and survival of cultured Delta Smelt from two different domestication index (DI) groups, capturing high DI and low DI values. Fish growth and survival were monitored in the hatchery from larval to adult life-stages to determine differences between DI groups. Our findings indicate that DI can have a significant influence as we observed reduced growth and survival of low DI fish at multiple life-stages. The results suggest that the DI of released hatchery-reared Delta Smelt may affect the performance of their offspring in the natural environment. Further studies might be necessary to develop a better management strategy on the released fish to enhance the conservation efforts.”

Featured Dataset Publications

  • None this month.

Featured Websites

  • Department of Water Resources Updates
    One of the primary goals of the Department of Water Resources (DWR) is to use the newest and best available science for water management. DWR also pioneers that science, as shown recently in an article about “Using Genetic Identification to Find Spring-run Salmon and More.” Earlier this month, DWR senior environmental scientist Sarah Brown was invited to Washington D.C. to participate in the 3rd National Workshop on Marine eDNA and to present DWR’s new eDNA Strategy (pdf).

    Environmental DNA, or eDNA, is the DNA that animals and plants leave behind as they pass through their environment. New genetic tools are allowing scientists to take basic water samples and scan it for DNA of specific species. The power of these new tools to rapidly obtain comprehensive information about biological communities in our fresh and marine waters is opening exciting new doors for natural resource management.

    Check out the DWR Updates pages at their website!
     
  • California Water Science Center
    Be sure to find what’s available at the USGS web site for the California Water Science Center Newsletters! Links to recent versions as well as to many more USGS science-related web and data content are available online.
  • Frontiers for Young Minds
    Where the river meets the ocean - Stories from San Francisco Estuary