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Status of selenium in south San Francisco Bay—A basis for modeling potential guidelines to meet National tissue criteria for fish and a proposed wildlife criterion for birds

Open-File Report 2018-1105

Prepared in cooperation with the U.S. Environmental Protection Agency
By:
ORCID iD and ORCID iD
https://doi.org/10.3133/ofr20181105

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Abstract

The U.S. Environmental Protection Agency (EPA) proposed Aquatic Life and AquaticDependent Wildlife Criteria for Selenium (Se) in California’s San Francisco Bay and Delta (Bay-Delta) in June 2016. Here we apply the same modeling methodology—Ecosystem-Scale Selenium Modeling— to an assessment of conditions and documentation of food webs of south San Francisco Bay (South Bay) as an exploratory framework in support of site-specific Se criteria development. Long-term datasets contribute to the basis for modeling, especially the 21-year collection of the clam Macoma petalum from a mudflat at the lower end of South Bay (Lower South Bay). As such, this is a working document that may serve as a basis to establish an understanding of the specifics of Se biodynamics within the estuary and reduce uncertainties about how to protect it. This approach brings together the main factors involved in toxicity: likelihood of high exposure, inherent species sensitivity, and the behavioral ecology (for example, demographics and life history) of an organism in terms of susceptibility to a reproductive toxicant. Species sensitivity is represented here by use of the EPA’s current national tissue Se criterion for fish or that proposed to protect the eggs of aquatic birds for the Bay-Delta (U.S. Environmental Protection Agency, 2016a, 2016b, 2016c). This report also strives to bring together findings and field data across a body of literature for South Bay to provide an integrative assessment.

We find an assemblage of site-specific conditions that could affect modeling:
associated urban processes such as discharges from municipal wastewater treatment plants and drainage from mercury (Hg) mining and limestone extraction are sources of Se that characterize the Lower South Bay as the location of interest for Se exposure; • hydrodynamics are lagoon-like (that is, less flushing), which sustains elevated nutrients and phytoplankton blooms; • managed freshwater sources are a major hydrodynamic component; • birds, in addition to fish, are prominent predators in South Bay; • wetland restoration has recently intervened to play a significant role in ecosystem function that may include uptake of both Hg and Se; • the dietary food web of surficial-sediment to M. petalum is important because of the dominance of this clam species and its elevated Se bioaccumulation potential compared to other local food webs; and 2 • maximal Se concentrations may be limited by transitory or annually renewed food webs (for example, migratory shorebirds and decimation of clams from marshes). We also find that the constructed mechanistic model: • spatially connects to the Palo Alto mudflat site because of data availability; • accurately predicts average observed Se concentrations in M. petalum and in predator species of fish and birds; and • is able to bracket a range of potential protective water-column Se concentrations specific to predator species based on the EPA’s national Se criterion for whole-body fish tissue and a proposed site-specific criterion for bird eggs in the Bay-Delta.

Suggested Citation

Luoma, S.N., and Presser, T.S., 2018, Status of selenium in south San Francisco Bay—A basis for modeling potential guidelines to meet National tissue criteria for fish and a proposed wildlife criterion for birds: U.S. Geological Survey Open-File Report 2018–1105, 75 p., https://doi.org/10.3133/ofr20181105.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Abstract
  • Introduction
  • Regulatory Actions and Policies
  • South San Francisco Bay Ecosystem
  • Influence of Ecosystem Characteristics on Selenium
  • Sources of Selenium in South Bay
  • Selenium Concentrations in South Bay Waters
  • Selenium Concentrations in South Bay Sediments
  • Selenium Concentrations in South Bay Invertebrates
  • Selenium Concentrations in South Bay Fish
  • Selenium Concentrations in South Bay Birds
  • Presser-Luoma Ecosystem-Scale Selenium Model
  • Transformation Coefficients (Kds)
  • Trophic Transfer Factors (TTFs)
  • Model Validation
  • Calibration of TTFs for M. petalum
  • Water-Column Selenium Guidelines
  • Exceedances
  • Conclusions
  • References Cited
  • Supplementary References
  • Appendix

Additional publication details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Status of selenium in south San Francisco Bay—A basis for modeling potential guidelines to meet National tissue criteria for fish and a proposed wildlife criterion for birds
Series title:
Open-File Report
Series number:
2018-1105
DOI:
10.3133/ofr20181105
Year Published:
2018
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
National Research Program - Western Branch
Description:
v, 75 p.
Country:
United States
State:
California
Other Geospatial:
San Francisco Bay
Online Only (Y/N):
Y