1996 Progress Report: Mercury Uptake by Fish

EPA Grant Number: R825433C010
Subproject: this is subproject number 010 , established and managed by the Center Director under grant R825433
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EERC - Center for Ecological Health Research (Cal Davis)
Center Director: Rolston, Dennis E.
Title: Mercury Uptake by Fish
Investigators: Cech, Joseph
Institution: University of California - Davis
EPA Project Officer: Packard, Benjamin H
Project Period: June 30, 1995 through June 30, 1998
Project Period Covered by this Report: June 30, 1995 through June 30, 1996
RFA: Exploratory Environmental Research Centers (1992) RFA Text |  Recipients Lists
Research Category: Center for Ecological Health Research , Targeted Research


Fish are abundant in Clear Lake and, thus, are important components of the lake's food web. The nineteen fish species which inhabit Clear Lake ingest various invertebrates (e.g. insects, crustaceans, zooplankton), fish, and green algae as prey.

Progress Summary:

Mercury concentrations found in Clear Lake fishes are highest in piscivorous species such as the largemouth bass (Micropterus salmoides). Sacramento blackfish (Orthodon microlepidotus), which filter zooplankton and algae from large volumes of water pumped over their gill rakers, carry only half of the mercury body burden as bass. Many of the fishes are preyed upon by birds (e.g. western grebe, bald eagle) and mammals, including humans. A public health advisory was issued in 1986 concerning consumption of piscivorous gamefish and is still maintained today. Our research plan is to describe the routes and rates of mercury uptake and transport through two fish species in the Clear Lake food web. Current studies are emphasizing mercury uptake from water (across the gills) in laboratory experiments on Sacramento blackfish under various temperature, dissolved oxygen and humic substance concentration conditions. For example, we recently measured a 74% decrease in methyl mercury uptake rate across the gills of blackish when 2 mg dissolved organic carbon (DOC)/L (humic substances) is present in the water. Apparently the DOC complexes the methyl mercury, limiting its bioavailability.

Future Activities:

Our objective in the next phase is to determine mercury uptake rates from dietary sources. Using intact largemouth bass and Sacramento blackfish (and, possibly, sections of intestinal wall), uptake rates of mercury-containing and control food items will be determined. Net flux rates will be determined by samples of fish and water taken through the experimental time period. Seasonal changes in uptake and depuration rates will be determined by altering experimental temperature and photoperiods. Fish health and population effects will be estimated by measuring food consumption, growth and survival rates in the experimental groups. The effect of fish intestinal microflora on methylation mercury will be determined by experimental administration of antibiotic compounds. Field samples of these fish from the Oaks and (adjacent) Lower Arms will assess population effects including mercury acclimatization. Statistic comparisons (e.g., ANOVA) will be made among the experimental groups to ascertain significance of environmental effects on mercury uptake and depuration rates. Models describing the relationships between uptake rates and these effects.

Supplemental Keywords:

fish, uptake, mercury, contamination, diet., RFA, Scientific Discipline, Toxics, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, mercury transport, Aquatic Ecosystem, Microbiology, Environmental Microbiology, Biochemistry, Environmental Monitoring, Biology, 33/50, mercury uptake, metabolic chamber study, food chain, fish consumption, Clear Lake, aquatic ecosystems, mercury & mercury compounds, mercury contamination in fish, metabolic chamber studies, heavy metals, lake ecosystems

Progress and Final Reports:

Original Abstract
  • 1995
  • Final

  • Main Center Abstract and Reports:

    R825433    EERC - Center for Ecological Health Research (Cal Davis)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R825433C001 Potential for Long-Term Degradation of Wetland Water Quality Due to Natural Discharge of Polluted Groundwater
    R825433C002 Sacramento River Watershed
    R825433C003 Endocrine Disruption in Fish and Birds
    R825433C004 Biomarkers of Exposure and Deleterious Effect: A Laboratory and Field Investigation
    R825433C005 Fish Developmental Toxicity/Recruitment
    R825433C006 Resolving Multiple Stressors by Biochemical Indicator Patterns and their Linkages to Adverse Effects on Benthic Invertebrate Patterns
    R825433C007 Environmental Chemistry of Bioavailability in Sediments and Water Column
    R825433C008 Reproduction of Birds and mammals in a terrestrial-aquatic interface
    R825433C009 Modeling Ecosystems Under Combined Stress
    R825433C010 Mercury Uptake by Fish
    R825433C011 Clear Lake Watershed
    R825433C012 The Role of Fishes as Transporters of Mercury
    R825433C013 Wetlands Restoration
    R825433C014 Wildlife Bioaccumulation and Effects
    R825433C015 Microbiology of Mercury Methylation in Sediments
    R825433C016 Hg and Fe Biogeochemistry
    R825433C017 Water Motions and Material Transport
    R825433C018 Economic Impacts of Multiple Stresses
    R825433C019 The History of Anthropogenic Effects
    R825433C020 Wetland Restoration
    R825433C021 Sierra Nevada Watershed Project
    R825433C022 Regional Transport of Air Pollutants and Exposure of Sierra Nevada Forests to Ozone
    R825433C023 Biomarkers of Ozone Damage to Sierra Nevada Vegetation
    R825433C024 Effects of Air Pollution on Water Quality: Emission of MTBE and Other Pollutants From Motorized Watercraft
    R825433C025 Regional Movement of Toxics
    R825433C026 Effect of Photochemical Reactions in Fog Drops and Aerosol Particles on the Fate of Atmospheric Chemicals in the Central Valley
    R825433C027 Source Load Modeling for Sediment in Mountainous Watersheds
    R825433C028 Stress of Increased Sediment Loading on Lake and Stream Function
    R825433C029 Watershed Response to Natural and Anthropogenic Stress: Lake Tahoe Nutrient Budget
    R825433C030 Mercury Distribution and Cycling in Sierra Nevada Waterbodies
    R825433C031 Pre-contact Forest Structure
    R825433C032 Identification and distribution of pest complexes in relation to late seral/old growth forest structure in the Lake Tahoe watershed
    R825433C033 Subalpine Marsh Plant Communities as Early Indicators of Ecosystem Stress
    R825433C034 Regional Hydrogeology and Contaminant Transport in a Sierra Nevada Ecosystem
    R825433C035 Border Rivers Watershed
    R825433C036 Toxicity Studies
    R825433C037 Watershed Assessment
    R825433C038 Microbiological Processes in Sediments
    R825433C039 Analytical and Biomarkers Core
    R825433C040 Organic Analysis
    R825433C041 Inorganic Analysis
    R825433C042 Immunoassay and Serum Markers
    R825433C043 Sensitive Biomarkers to Detect Biochemical Changes Indicating Multiple Stresses Including Chemically Induced Stresses
    R825433C044 Molecular, Cellular and Animal Biomarkers of Exposure and Effect
    R825433C045 Microbial Community Assays
    R825433C046 Cumulative and Integrative Biochemical Indicators
    R825433C047 Mercury and Iron Biogeochemistry
    R825433C048 Transport and Fate Core
    R825433C049 Role of Hydrogeologic Processes in Alpine Ecosystem Health
    R825433C050 Regional Hydrologic Modeling With Emphasis on Watershed-Scale Environmental Stresses
    R825433C051 Development of Pollutant Fate and Transport Models for Use in Terrestrial Ecosystem Exposure Assessment
    R825433C052 Pesticide Transport in Subsurface and Surface Water Systems
    R825433C053 Currents in Clear Lake
    R825433C054 Data Integration and Decision Support Core
    R825433C055 Spatial Patterns and Biodiversity
    R825433C056 Modeling Transport in Aquatic Systems
    R825433C057 Spatial and Temporal Trends in Water Quality
    R825433C058 Time Series Analysis and Modeling Ecological Risk
    R825433C059 WWW/Outreach
    R825433C060 Economic Effects of Multiple Stresses
    R825433C061 Effects of Nutrients on Algal Growth
    R825433C062 Nutrient Loading
    R825433C063 Subalpine Wetlands as Early Indicators of Ecosystem Stress
    R825433C064 Chlorinated Hydrocarbons
    R825433C065 Sierra Ozone Studies
    R825433C066 Assessment of Multiple Stresses on Soil Microbial Communities
    R825433C067 Terrestrial - Agriculture
    R825433C069 Molecular Epidemiology Core
    R825433C070 Serum Markers of Environmental Stress
    R825433C071 Development of Sensitive Biomarkers Based on Chemically Induced Changes in Expressions of Oncogenes
    R825433C072 Molecular Monitoring of Microbial Populations
    R825433C073 Aquatic - Rivers and Estuaries
    R825433C074 Border Rivers - Toxicity Studies