Grantee Research Project Results

Final Report: Wetlands Restoration

EPA Grant Number: R825433C013
Subproject: this is subproject number 013 , 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: UC Davis Center for Children's Environmental Health and Disease Prevention
Center Director: Van de Water, Judith
Title: Wetlands Restoration
Investigators: Rejmankova, Eliska
Institution: University of California - Davis
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1996 through September 30, 2000
RFA: Exploratory Environmental Research Centers (1992) RFA Text |  Recipients Lists
Research Category: Center for Ecological Health Research , Targeted Research

Objective:

The overall objective of this research project at Clear Lake and marshes surrounding the lake was to investigate the effects of wetlands on the lake's water quality. The specific objectives of this research project were to examine: (1) how wetland plant species can affect nutrient budgets; (2) how much of the nutrients can be retained in wetland sediment before getting into the lake; and (3) the change in the sedimentation rate of soil and nutrients since watershed modification by humans. Our research project increased understanding of the role of wetlands in the Clear Lake Watershed, and provided important guidelines for ongoing restoration projects and wetland management.

Summary/Accomplishments (Outputs/Outcomes):

Initially, we addressed the selection of suitable plant species for use in wetlands restoration. We conducted a set of experiments on the combination of emergent macrophyte with an aquatic, nitrogen-fixing fern and the effect of an aquatic fern on the nutrient budget of emergent macrophytes. These experiments and other surveys resulted in the recommendation of the following species as suitable candidates for restoration in the Clear Lake region: (1) emergent macrophytes: Scirpus acutus, Scirpus californicus, Typha latifolia, Zizzania aquatica, Ludwigia peploides; and (2) floating macrophytes: Azolla spp. In addition to herbaceous species, we recommend willow shrubs (Salix spp.) for riparian wetland restoration, and we have suggested appropriate cultivation procedures.

A large wetland on the northwest side of the Clear Lake has been diked, drained, and used for agriculture for many years, but Anderson Marsh on the southeast side of Clear Lake has been impacted only minimally by agricultural activities. These changes around Rodman Slough led to an increase of water current and, as a result, a decrease in the sedimentation of small particles in the marsh and on the slough bottom. However, nutrient input, such as N and P, has increased from the use of fertilizers in surrounding agricultural land. To assess the response of Clear Lake wetland sediments to environmental changes caused by watershed modification since European settlement in the early 1800s, we compared physical and chemical properties of sediment cores at the inlet (Rodman Slough) and outlet (Anderson Marsh). We found that the sediment in Rodman Slough is allochthonous (sand) and has very little organic matter. In contrast, the sediment in Anderson Marsh is autochthonous (peat) and has high organic content. Concentrations of C, N, P, Ca, K, and Na in Rodman Slough sediment were lower than those of Anderson Marsh sediment. Accumulation rates of P, Ca, and K were much higher in Rodman Slough than in Anderson Marsh, and accumulation rates of C, N, and Na were similar at both locations. Water and sediment analyses showed that the excess P and N, originating from agricultural activities, reach Clear Lake through Rodman Slough. Major cations (Ca, Mg, K, and Na) were concentrated in the lake through evaporation and transpiration. ²¹⁰Pb dating showed an increase in the sedimentation rate for Anderson Marsh since the 1930s.

The following activities were accomplished:

• Our wetland plant surveys and mesocosm experiments indicate several wetland species as suitable candidates for wetland restoration at Clear Lake. The following emergent macrophytes would be good candidates for restoration: S. acutus, S. californicus, T. latifolia, Z. aquatica, L. peploides. Azolla spp. (a floating macrophyte) and willow shrubs (Salix spp.) also would be suitable candidates. We suggested appropriate cultivation procedures for restoring willow shrubs. Identifying these candidates was an important component of the restoration efforts because they have the highest potential to be most effectively restored, giving the entire wetlands restoration project a better chance at success.

• Sediment core analyses show increased sedimentation rates and increased P input into the lake. 210Pb dating showed increases in the sedimentation rate for Anderson Marsh (the lake’s inlet) in the 1930s and 1980s. The accumulation rates of P, Ca, Mg, K, and Pb were slightly higher in Rodman Slough (outlet) than in Anderson Marsh. Sediment analyses showed that the excess P originating from agricultural activities reaches Clear Lake through Rodman Slough. Because the sedimentation rates are higher at the inlet than at the outlet, the lake is “cleansing” itself of extra sediment (in a sense). Restoration managers working at Clear Lake can use this information in further assessing sedimentation problems.

• Previous studies were focused on wetland plants because wetlands function as "nutrient sinks"; their presence can act to lessen the load of nutrients from agricultural usage to the lake. In contrast, our study stressed the importance of monitoring the change in sediment characteristics that results from the restoration project and other environmental changes. Based on our results and future monitoring, restoration managers can evaluate and modify the direction of the restoration project.

• Our research project gives restoration managers an increased understanding of the role of wetlands in the Clear Lake Watershed, and provides important guidelines for ongoing restoration projects and wetland management.

Supplemental Keywords:

ecosystem, ecosystem protection, environmental exposure and risk, geographic area, international cooperation, water, terrestrial ecosystems, aquatic ecosystem, aquatic ecosystem restoration, aquatic ecosystems and estuarine research, biochemistry, ecological effects, ecological indicators, ecological monitoring, ecology and ecosystems, environmental chemistry, restoration, state, water and watershed, watershed, watershed development, watershed land use, watershed management, watershed modeling, watershed restoration, watershed sustainability, agricultural watershed, exploratory research environmental biology, California, CA, Clear Lake, Lake Tahoe, anthropogenic effects, aquatic habitat, biogeochemical cycling, ecological assessment, ecology assessment models, ecosystem monitoring, ecosystem response, ecosystem stress, environmental stress, environmental stress indicators, fish habitat, hydrologic modeling, hydrology, integrated watershed model, lake ecosystems, lakes, land use, nutrient dynamics, nutrient flux, water management options, water quality, wetlands., RFA, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, INTERNATIONAL COOPERATION, Water, ECOSYSTEMS, Aquatic Ecosystem, Restoration, Aquatic Ecosystems & Estuarine Research, Terrestrial Ecosystems, Aquatic Ecosystem Restoration, Watersheds, Environmental Microbiology, Biochemistry, Water & Watershed, Ecology and Ecosystems, Environmental Monitoring, contaminant exposure, lake ecosysyems, nutrient flux, marine biogeochemistry, marine biology, watershed management, wetland plant species, restoration planning, water quality, biodiversity, ecological impact, restoration strategies, watershed restoration, fish habitat, ecosystem stress, environmental stress, wetland restoration, integrated watershed model, aquatic habitat protection , ecological research, Clear Lake watershed, agricultural watershed, aquatic ecosystems, nutrient transport, anthropogenic stress, nutrients, mercury

Relevant Websites:

http://ice.ucdavis.edu/cehr/ Exit

Progress and Final Reports:

Original Abstract

1997

1998

1999

Main Center Abstract and Reports:

R825433    UC Davis Center for Children's Environmental Health and Disease Prevention

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