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2000 Progress Report: Clear Lake Watershed
EPA Grant Number: R825433C011Subproject: this is subproject number 011 , 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: Clear Lake Watershed
Investigators: Suchanek, Thomas , Anderson, Daniel , Cech, Joseph , Goldman, Charles R. , Layton, David , Rejmankova, Eliska , Richerson, Peter , Schladow, S. G. , Wilen, James
Institution: University of California - Davis
EPA Project Officer: Levinson, Barbara
Project Period: October 1, 1996 through September 30, 2000
Project Period Covered by this Report: October 1, 1999 through September 30, 2000
RFA: Exploratory Environmental Research Centers (1992)
Research Category: Center for Ecological Health Research , Targeted Research
Description:
Objective:The goal of the research is to test new analytical methods and hypotheses on how multiple stresses interact to affect target organisms and management endpoints of interest. We wish to demonstrate how technical information can be brought to managers to solve practical problems.
Clear Lake and its watershed constitute a complex ecosystem with multiple management objectives and several major stressors at work. The lake is a large (second largest in California), shallow, eutrophic system heavily used for recreation and water supply. It is an important habitat for waterfowl and fish-eating birds and mammals. Human uses conflict among themselves and with biodiversity values. It is an excellent laboratory ecosystem for the testing of concepts and methods for the management of multiple stresses. Clear Lake contrasts sharply in trophic state and other parameters with Lake Tahoe, making comparative studies particularly interesting, especially since both lakes have good long-term records.
Our investigations of the problem of mercury ecotoxicology in Clear Lake are among the most thorough ever conducted on one ecosystem. We have the data and methods in hand to understand the movement of Hg through this system from mine to grebe and osprey from mass-balance first principles. We have made progress even on some of the most difficult questions such as rates of mercury methylation and demethylation, mechanisms of fish uptake of Hg, and the relative role of Clear Lake in generating exposures of migratory birds. Our investigations of the role of habitat disturbance (stream channel damage, road building, wetland loss) in the eutrophication of the lake led to the hypothesis that the advent of powered earthmoving machinery in the 1920s caused a pervasive pattern of watershed disturbance. Our recent core data, show a dramatic increase in mercury loading, sediment influx and many other changes in the last few decades, consistent with the hypothesis. The advent of European settlement in the mid 19th Century is much less dramatic. We have made good progress in reconstructing the joint exposure of birds to mercury and chlorinated hydrocarbons in the 1950s, when a grebe population collapse occurred, attributed to DDD food chain accumulation in a classic investigation, recounted by Rachel Carson in Silent Spring. Mercury was unstudied at the time, but the availability of feathers and other tissues in museum collections, plus the information on exposures derived from the cores, will allow us to test the hypothesis that multiple exposures to the two stressors occurred.
Figure B-1 shows the major stresses affecting the system on the left hand side and the major management objectives on the right. The recreational, aesthetic, and wildlife conservation values at risk from stresses are the same scale of complexity and type as in many other aquatic ecosystems. The focus of our investigations are the complex ecosystem processes that link stresses to management problems.
Figure B-1. Multiple Stresses and Management Objectives at Clear Lake
In our research we are making three contributions to applied ecology. First, we are developing a very good case study of a multiply-stressed ecosystem. In the end, much of our ability to understand and manage such systems will come from the comparative analysis of many such cases. Second, we are investigating ecotoxicological processes and their interactions with other ecosystem processes. Our focal chemical is mercury. The Sulphur Bank Mercury Mine (a Superfund site) contaminates the lake to levels that trigger health warnings for human consumption of fish. The movement of mercury from inorganic pools into the food chain of Clear Lake is affected by a myriad of ecological processes, including other anthropogenic stresses. For example, eutrophication due to watershed disturbances favors the growth of large toxic scum forming cyanobacteria which are little grazed by zooplankton but are mineralized disproportionately by sediment microbes. The sediment microbial community is probably responsible for the lion's share of the inorganic mercury converted to methylmercury, the form which contaminates the food chain leading to fish, humans, and fish-eating birds and mammals. Third, we are investigating methods for understanding multiply stressed ecosystems using the concept of a "sufficiently comprehensive investigation." Applied ecologists will never have sufficient resources to study all of the complex matter, energy, and population processes symbolized by the tangle in the center of Figure B-1. What is necessary is to select the most important management objectives and trace backwards through the ecological processes to understand the most important links between stresses and objectives. The result is a working hypothesis about the operation of the system from a practical point of view. Our current view is illustrated in Figure B-2.
Figure B-2. Clear Lake Research Plan Indicating the Topics Covered by Watershed Projects (solid line) and Core Affiliates (dashed line)
Under Center auspices the Clear Lake watershed is developing into an excellent laboratory ecosystem for pursuing these three goals. Although the aggregate support from non-Center sources considerably exceeds Center funding, none of the other contributing projects allows an integration of all projects to give a systemic view of the watershed and its problems. We target Center funds on essential projects for integration, such as the economic analysis of the relative importance of the different management problems conducted by Drs. Wilen and Layton and their students. We use Center funds to support pilot projects, such as our environmental history/coring project, which should eventually attract substantial external funding. We benefit from having access to Core projects. For example, a hydrodynamic model of Clear Lake was developed, partly with support from the Data Integration and Decision Support Core.
The Center is also a forum for comparative discussions of watershed scale problems. The Clear Lake history/coring project is closely modeled on a similar project at Tahoe, partly because we can take advantage of expertise developed by Tahoe workers, but also because the comparisons of the stresses affecting these two watersheds, contrasting sharply in some dimensions (trophic state), but similar in others (summer arid climate), will be illuminating.
As noted above, the Center-funded research at Clear Lake is closely coordinated with management agencies and their objectives. There is a great deal of synergy generated by the interaction of the Center investigations of Hg ecotoxicology and the Superfund Ecological Assessment and Remediation Investigation of Sulphur Bank Mercury Mine. On the one hand, the Superfund project supports a much more detailed descriptive analysis of the Hg contamination of the lake than any applied science program could afford. On the other, the Center can support research issues that Superfund is forbidden from funding, even if they have a considerable bearing on management issues at Sulphur Bank. Our work on the algal bloom/eutrophication problem, initially funded by the EPA Clean Lakes program and the County resulted in recommendations, which in turn have been used by the County to secure several hundred thousand dollars in habitat restoration grants. For example, on the basis of recommendations based upon preliminary results of this study and other considerations, the County has secured funds for a design study with the Army Corps of Engineers to plan the restoration of 750 acres of agricultural land for use as a wetland settling basin in the Rodman Slough Area. The County will be applying for funds to purchase the land once this design study is completed, and the results of our investigation should receive a large-scale test. We collaborate with County Flood Control and Lakebed Management staff on algal bloom, habitat restoration, and nutrient cycling projects. Lake County is the lead management agency for many aspects of the watershed, and, in collaboration with the major Federal, State, and local stakeholders, participates in a Clear Lake Basin Integrated Resource Management Committee. Drs. Richerson and Suchanek represent UCD as regular voting participants in the Clear Lake Advisory Subcommittee of the Basin Committee. Our researchers have provided personal technical counsel to County supervisors, the County Air Quality, Mosquito Abatement, and Flood Control and Lakebed Management agencies, members of the Regional Water Quality Control Board, newspaper reporters, and private citizens. Center Investigators are working with the Indian Programs Team at EPA and University Extension to develop an environmental training program specifically aimed at issues which directly affect the Big Valley Pomo Indian Tribe. Our investigators have also served on committees advising the City of Sacramento, Yolo County, and the University of Nevada-Reno based upon participation in the Clear Lake Watershed investigations.
Supplemental Keywords:Ecosystem Protection/Environmental Exposure & Risk, Water, INTERNATIONAL COOPERATION, Scientific Discipline, RFA, ECOSYSTEMS, Water & Watershed, Restoration, Aquatic Ecosystem Restoration, Aquatic Ecosystems & Estuarine Research, Mercury, Terrestrial Ecosystems, Aquatic Ecosystem, Biochemistry, Environmental Microbiology, mercury transport, Watersheds, Ecology and Ecosystems, Environmental Monitoring, ecological impact, watershed management, watershed restoration, mercury uptake, Clear Lake, ecological research, fish-eating birds, lake ecosystems, agricultural watersheds, contaminant exposure, agricultural watershed, aquatic ecosystems, environmental stress, marine biogeochemistry, watershed influences, anthropogenic stress, restoration strategies, ecosystem stress, Clear Lake watershed, biodiversity
Progress and Final Reports:
Original Abstract
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