Welcome to The State of Bay-Delta Science

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ABOUT

The State of Bay-Delta Science (SBDS) is an ongoing synthesis and communication effort intended to inform science and policy audiences about the “state of the science” for topics relevant to the management of the Bay-Delta system. Editions of SBDS consist of collections of scientific articles published in the peer-reviewed journal San Francisco Estuary and Watershed Science (SFEWS). While the first two editions of SBDS covered a broad range of topics, the 2022 and future editions contain smaller suites of articles focused on key issues identified by the SBDS Editorial Board.

The 2022 edition features seven articles exploring the theme of “ecosystem services and disservices of Bay-Delta primary producers: how plants and algae affect ecosystems and respond to management of the estuary and its watershed.” Articles are available in the February 2023 issue of SFEWS. More information about this edition is available in this information sheet and in the State of Bay-Delta Science 2022 Executive Summary.

The next edition of SBDS is currently in production and will feature a suite of articles exploring “extreme climatic and weather events and their impacts on the Bay-Delta.” Articles are anticipated to be released in 2024.

2022 EDITION TOPICS

Introduction

Ecosystem services and disservices of Bay-Delta primary producers: how plants and algae affect ecosystems and respond to management of the estuary and its watershed

Laurel G. Larsen, Samuel M. Bashevkin, Maggie Christman, J. Louise Conrad, Clifford N. Dahm, Janet Thompson

Article link: https://doi.org/10.15447/sfews.2023v20iss4art1

This themed edition of The State of Bay-Delta Science includes six topical chapters exploring the important contributions and impacts of plants and algae (i.e., primary producers) in the Bay-Delta system. Collectively, these articles address research priorities identified in the 2022-2026 Science Action Agenda and allows Delta scientists and managers to address questions such as “What is the relative value in investing in invasive aquatic weeds control for fish relative to promoting wetland restoration?” or “How might alternative strategies for wetland restoration impact Delta sediment and carbon balances, invasive aquatic vegetation coverage, and economic and recreation impacts on human communities?”

Primary production

Landscape transformation and variation in invasive species abundance drive change in primary production of aquatic vegetation in the Sacramento–San Joaquin Delta

Katharyn E. Boyer, Samuel M. Safran, Shruti Khanna, and Melissa V. Patten

Article link: https://doi.org/10.15447/sfews.2023v20iss4art2

Aquatic vegetation plays an important role in the flow of energy through ecosystems. Carbon that is assimilated through photosynthesis is released to food webs through herbivory and decomposition processes, and the net carbon provided by vegetation to ecosystems is quantified in a measurement of ‘net primary production.’ This chapter explores how changes in aquatic vegetation species, including new introductions of species and changes in the amount of invasive aquatic vegetation in the Delta, has affected net primary production and thus impacted food webs supporting native species.

Aquatic vegetation ecology

Ecology and ecosystem impacts of submerged and floating aquatic vegetation in the Sacramento-San Joaquin Delta

Maggie A Christman, Shruti Khanna, Judith Z Drexler, Matthew J Young

Article link: https://doi.org/10.15447/sfews.2023v20iss4art3

In the upper San Francisco Estuary, aquatic vegetation affects every aspect of the physical and biotic environment including ecosystem properties and processes. Impacts are constantly changing across space and time as species change in distribution, respond to environmental conditions, and new species are introduced. This chapter reviews the ecology of plant species found as submerged and floating aquatic vegetation communities in the modern Delta, including how environmental conditions drive changes in plant species and communities and how those species and communities in turn affect the physical and biotic environments in which they are found.

Aquatic vegetation control

Invasive Aquatic Vegetation in the Sacramento-San Joaquin Delta and Suisun Marsh: The History and Science of Control Efforts and Recommendations for the Path Forward

J. Louise Conrad, Madison Thomas, Karen Jetter, John Madsen, Paul Pratt, Patrick Moran, John Takekawa, Gina Skurka Darin, Lydia Kenison

Article link: https://doi.org/10.15447/sfews.2023v20iss4art4

Invasive aquatic vegetation is a major management challenge in the Sacramento-San Joaquin Delta and the Suisun Marsh due to its impacts on recreational and commercial boating, operation of critical water infrastructure, and numerous ecosystem impacts. Control efforts, including chemical, biological, mechanical, and physical approaches, have been a major resource investment for four decades, but the science of control efforts has only started in earnest in the early 2000s, with increased attention in just the last ten years. This chapter explores the history and supporting science of invasive aquatic vegetation control efforts in the Delta and Suisun Marsh in the context of control efforts used in other similar (e.g., flowing water) systems. The chapter concludes with a series of recommendations for continued advancement of science in support of adaptive management of invasive aquatic vegetation.

Remote sensing methods

Remote sensing of primary producers in the Bay-Delta

Erin Hestir, Iryna Dronova2

Article link: https://doi.org/10.15447/sfews.2023v20iss4art5

Remote sensing methods include a variety of techniques of capturing information about organisms or the physical environment from a distance, such as imagery captured from aircrafts, satellites, or drones. Collectively these methods are an effective tool to support monitoring plants and algae in the Delta across the full environmental gradient from water channels to wetlands and terrestrial environments. This chapter reviews the breadth of applications, considerations, and resolutions for remote sensing to address major questions regarding primary producers (e.g., plants and algae) in the Delta with an emphasis on how remote sensing technologies have evolved in recent years and the resulting advancements in knowledge that have resulted from their application.

Harmful algal blooms (HABs)

Status, Trends, and Drivers of Harmful Algal Blooms Along the Freshwater to Marine Gradient in the San Francisco Bay Delta System

Raphael M. Kudela, Meredith D. A. Howard, Stephen Monismith, Hans W. Paerl

Article link: https://doi.org/10.15447/sfews.2023v20iss4art6

Harmful algal blooms, commonly referred to as HABs, are phenomena in which algae and other phytoplankton (e.g., microscopic plant-like organisms) grow explosively in certain conditions and create negative impacts to people and the environment. Examples of these impacts include production of toxins, reduction of oxygen levels in waterways, disruptions of food webs or nutrient cycles, and generally poor conditions. This chapter reviews the species and toxins that are involved with HABs in the San Francisco Estuary, environmental conditions which drive blooms, and the resulting impacts of these blooms and toxins to humans and the environment.

Carbon sequestration and subsidence reversal

Carbon sequestration and subsidence reversal in the Sacramento-San Joaquin Delta and Suisun Bay: management opportunities for climate mitigation and adaptation

Lisamarie Windham-Myers, Patty Oikawa, Steve Deverel, Dylan Chapple, Judith Z. Drexler, Dylan Stern

Article link: https://doi.org/10.15447/sfews.2023v20iss4art7

Over the last few centuries, changing landscapes and land uses in the Delta have resulted in loss of land elevation (subsidence), emission of greenhouse gases, and depletion of carbon from Delta soils. This chapter reviews the state of the science underlying the processes of carbon sequestration (i.e., capturing and storing carbon on the landscape) and subsidence reversal (i.e., reversing loss of land elevation) in the Delta and specifically explores how management interventions involving manipulating flows, vegetation, and nutrients, could slow or reverse carbon loss from Delta soils.

PREVIOUS EDITIONS

The first edition of SBDS, produced in 2008, provided a system-wide baseline for the state of scientific knowledge of the system and a reframing of the interaction between policy and science. For the 2016 edition, the Editorial Board (Michael Healey, University of British Columbia; Michael Dettinger, US Geological Survey; and Richard Norgaard, Emeritus, UC Berkeley) identified the most relevant science issues based on a survey of senior scientists and managers working in the Delta. The 15 peer-reviewed papers that form SBDS 2016 cover issues ranging from contaminants in the Delta to levee stability, and from Delta food webs to recent discoveries about salmon migration.

In order to distill key findings in SBDS 2016 for a policymaker audience, Michael Healey and Richard Norgaard prepared a summary for policymakers entitled “The Delta on Fast Forward: Thinking Beyond the Next Crisis.” This summary presented seven new perspectives based on SBDS 2016, described a suite of tools that are advancing Delta science, and suggested eight forward-thinking actions for conducting science in the Delta.

To request a copy of previous reports, please contact archives@deltacouncil.ca.gov.

Watch a short video about the 2016 SBDS editions.

Editorial Board

Selection of themes and topics to explore in SBDS is guided by an Editorial Board comprising distinguished scientists from academia and agencies in addition to the Delta Lead Scientist and Delta Science Program staff.

Current SBDS Editorial Board

Janet Thompson - US Geological Survey (retired)

Cliff Dahm - University of New Mexico (retired) & former Delta Lead Scientist

Jessica Rudnick - California Sea Grant & Delta Stewardship Council

Laurel Larsen - University of California, Berkeley & current Delta Lead Scientist

Denise Colombano - Delta Science Program

Maggie Christman - Delta Science Program

Lynn Takata - Delta Science Program

Previous SBDS Editorial Board members (& editions)

Michael Healey (2008, 2016)

Michael Dettinger (2008, 2016)

Richard Norgaard (2008, 2016)

Louise Conrad (2022)

Sam Bashevkin (2022)

State of the Bay Delta Science

The State of Bay Delta Science. A Synthesis of our Current Understanding of the Bay Delta System