2002 Progress Report: Pacific Estuarine Ecosystem Indicator Research (PEEIR) Consortium: Biogeochemistry and Bioavailability Component

EPA Grant Number: R828676C003
Subproject: this is subproject number 003 , established and managed by the Center Director under grant R828676
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Pacific Estuarine Ecosystem Indicator Research (PEEIR) Consortium
Center Director: Anderson, Susan L.
Title: Pacific Estuarine Ecosystem Indicator Research (PEEIR) Consortium: Biogeochemistry and Bioavailability Component
Investigators: Higashi, Richard M. , Fan, Teresa W-M. , Holden, Patricia , Kuivila, Katherine , Nelson, Douglas , Scow, Kate
Current Investigators: Higashi, Richard M. , Cao, Yiping , Collins, Joshua N , Córdova-Kreylos, Analucis , Fan, Teresa W-M. , Green, Peter , Green, Sarah , Hechinger, Ryan , Holden, Patricia , Hollibaugh, James T. , Huspeni, Todd , LaMontagne, Michael , Lafferty, Kevin , Lay, Mui , Li, Lin , Melack, John , Myers, Monique , Page, Henry M. , Rosso, Pablo , Scow, Kate , Ustin, Susan L. , VanDeWerfhorst, Laurie
Institution: University of California - Davis , U.S. Geological Survey , University of California - Santa Barbara
Current Institution: University of California - Davis , San Francisco Estuary Institute , U.S. Geological Survey , University of California - Santa Barbara , University of Georgia
EPA Project Officer: Hiscock, Michael
Project Period: March 1, 2001 through February 28, 2005
Project Period Covered by this Report: March 1, 2001 through February 28, 2002
RFA: Environmental Indicators in the Estuarine Environment Research Program (2000) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Water , Ecosystems


The overall objective of this research project is to develop field indicators and the knowledge base to help assess the consequences of changes in chemical form of pollutants in tidal marshes. Most organic and inorganic pollutants relentlessly change chemical form due to biogeochemical processes. Different forms in turn define both toxicity and bioavailability. Our general objective is founded on two principles that involve biogeochemistry and bioavailability. Knowledge of factors involved in modifying chemical form and bioavailability is critical for accurately assessing and predicting organismal exposure and higher order ecotoxicological effects.

This research project's particular emphasis is on the assessment of metals and organic pollutant bioavailability in relation to sedimentary lower trophic-level biomarkers. This emphasis on rooted plants and sediment microbes is because they often are the entry point of pollutants into the food chain and are major drivers of the biogeochemistry of the tidal marsh. The specific objective of this research project is to uncover the chemical, biochemical, and biotic markers that herald the bioavailability, transport, and/or biotransformation of selected metal and organic pollutants. These markers, in appropriate concert with others generated by PEEIR, can comprise indicators of pollutant stress on marsh ecosystems.

Progress Summary:

Plant Indicators. The development of plant stress and indicators at multiple spatial scales is an important objective of the PEEIR Consortium. In the PEEIR group sampling effort during summer 2002, Spartina and Salicornia shoots and roots were obtained from Stege, Carpinteria, and Walker marshes at stations established for all investigators within PEEIR. The tissues were cleaned and preserved onsite by immersion in liquid nitrogen. Metabolite profiling by nuclear magnetic resonance and gas chromatography/mass spectrometry yielded patterns of more than 40 metabolites that can be compared with other PEEIR data from these same stations. For example, relatively decreased sucrose stores were observed in plants at the same Carpinteria station (station "B") that exhibited considerable toxicity to sea urchin gametes, the unusual and strong response of exogastrulation (see Biological Responses to Contaminants [BRC] Report), and highest levels of phthalates. As stated below, these highest phthalate stations also strongly correlated with certain peaks in the Terminal Restriction Fragment Length Polymorphism (T-RFLP) microbial community profiles (Holden project). In addition, suites of metals were analyzed in the plant samples in collaboration with Dr. Peter Green. Interestingly, the tissue metals did not correspond to the leaf exudates metals, indicating that the transpiration stream for metal exudation interacted little with the plant cells. Manganese content of Salicornia woody and green stems related to microbial diversity (Holden project). Lastly, growth-chamber studies with Spartina and Cd exposure was initiated, and the first range-finding experiment was completed. The laboratory studies are an important aspect of our synthetic efforts to develop plant indicators at multiple scales.

Plants were grown and exposed to diuron in a growth-chamber study of the uptake and metabolism of diuron by wetland plants. Diuron is a widely used herbicide that inhibits photosynthesis; thus, it impacts major functioning of plants that may be visible by remote sensing. Although frequently detected in water, diuron also sorbs to sediments; thus sediments may provide a continuous source of the pesticide to plants and aquatic organisms in wetlands. In conjunction with the Fan project, a series of laboratory studies measured the uptake and metabolism of diuron by native Spartina and Salicornia. The effects of diuron were estimated by measuring resulting changes in plant pigments and photosynthesis stress. The research with diuron also will help to validate metabolic indicators and their relationship to integrated responses of the plants.

Site Characterization. Analytical activity continued with the "Stressor Core" group including Gary Cherr (BRC) and Dr. Peter Green. The principal objective is to characterize contaminant organics, metals, and embryonic toxicity along gradients at PEEIR-wide established marsh stations. Sediment elutriates were analyzed from Stege, Carpinteria, Walker, and Mugu marshes that correspond to samples being analyzed by Holden, Scow, and Cherr (BRC) groups, and were in close proximity to plants collected by the Fan project, shoot metal exudates by Dr. Green, and invertebrate survey cores (Ecosystem Indicators Component [EIC] projects of Grosholz, Morgan, and Lafferty). One example of a preliminary relationship was high elutrate Cu at Stege marsh stations that exhibited high gamete toxicity (BRC project of Cherr). Also at Stege marsh, station "C" with the highest Cd leaf exudates also posted by far the lowest Streblospio and highest Enchytraeidae abundances (EIC projects of Grosholz and Morgan). Other examples of the Stressor Core findings and connections to other PEEIR research results are found in several descriptions above and below, as well as in the BRC section's annual report.

Microbial Responses. Microbial community composition and diversity in sediments, as assessed by high-throughput T-RFLP analysis, was determined on sediment samples collected over 2 years of sampling. Interestingly, relationships with plant biochemical markers and contaminants were discerned; for example, certain T-RFLP peaks (identity currently unknown) associated strongly with dibutylphthalate in elutriates (Higashi project), which in turn were highest at Carpinteria marsh stations that exhibited the highly unusual exogastrulation of embryos (BRC project of Cherr) and low plant sucrose stores (Fan project). As mentioned above, Salicornia woody/green relationships of Mn (Fan/Williams project) also related to microbial diversity as estimated by T-RFLP. Relationships to Phospholipid Fatty Acid (PLFA) data (Scow project) are being explored.

Our focus continued to be on methods to assess inorganic mercury methylation in estuarine sediments and to develop potential indicators of mercury exposure for the Walker Creek site. Pure cultures of another type of anaerobic bacteria (iron reducers) that are surprisingly active methylators have been isolated, in addition to the sulfate reducers of current dogma. This provides a second target for the assessment of the dominant methylators in the estuarine environments. Key analytical tools were added including the ability to obtain very high-quality denaturing gradient gel electrophoresis (DGGE) gels from anoxic sediments, with sequencing of the resultant rRNA bands for phylogenetic and physiological perspectives on the dominant microbes. One major new analytical tool was obtained very recently using PEEIR funds: the Milestone DMA-80, which analyzes for total mercury via EPA 7473 ("Thermal Decomposition Amalgamation with Atomic Absorption Spectrophotometry"). This is an automated instrument that requires little to no sample preparation for tissues and sediments and is capable of single-digit ppb analyses of total mercury. Currently undergoing calibration and tests in the laboratory, this instrument is expected to support extensive surveys of marsh sediment and organism loads of mercury for PEEIR researchers, and together with (DGGE, will enable a better understanding of estuarine mercury methylation by microbial communities.

PLFA analysis was performed on sediment cores to examine the microbial communities. The fingerprinting was performed for sites at Stege, Carpinteria, Mugu, and Walker marshes. Cores were taken at different sampling stations along the main channel, and at each station, three elevations were sampled: low (bottom of the channel), med (slope), and high (vegetated area on top of channel). Sampling was performed by pooling six to eight cores in a sterile glass jar. From this pooled sample, one core was retrieved for PLFA fingerprinting and other cores were retrieved for T-RFLP and elutriate water analysis by other members of the Biogeochemistry and Bioavailability Component (BBC) (Higashi project, BRC project of Cherr). The preliminary statistical analysis of the data was performed in CONOCO and Sigma Plot software.

A summary table of the PLFA information available to date is available upon request. Another way of looking at the PLFA data is to compare the mass of specific lipid biomarkers that are indicators of particular groups of microorganisms. The biomarkers obtained for some major groups of organisms in soil, as well as the average number of lipids and the total PLFA extracted, include the proportion of branched (Gram positive bacteria marker), cyclopropyl (aerobic bacteria markers), and linoleic acid (18:2omega6c: fungal biomarker) for subgroups of the samples. However, the biomarker data needs to be interpreted with caution; not all biomarkers are exclusive to a particular group and it is possible that some members of a particular group may not have that biomarker. Currently, we are working with other PEEIR researchers to explore the data for correlations between pollutant gradients (Higashi project, BRC project of Cherr) and PLFA fingerprints. Further results of this study will be presented at the Estuarine Research Foundation Conference in Seattle, WA (September 14-18, 2003).

Future Activities:

The BBC investigators have expended intense effort to provide analytical data and collaborations on chemistry research with the EIC and BRC components. Several examples of this are given above and many more instances are expected to emerge as the current data are cross examined with that from other PEEIR sections. The cross-sectional Stressor Core activities will be brought to some sort of "closure" in 2003-2004, although present plans call for a temporary increase in activity to support the animal transplant experiments planned for summer of 2003 by BRC and EIC.

A new organic chemistry component is being added to provide improved characterization of toxic compounds at our key sites. As field work is completed this year, further integration activities will include participation in working teams to forward recommendations on plant indicators at multiple spatial scales, as well as to develop indicators for model animals that related chemistry to stressor measurements and ultimately to changes in populations. Furthermore, methodologies useful to the U.S. Environmental Protection Agency will be detailed and technology transfer possibilities will be discussed. For example, Dr. Green already has participated in the Environmental Monitoring and Assessment Program-West monitoring of wetland sites. His method of analysis of salt excretions in wetland plants as an indicator of toxic metal bioavailability may soon be ready for broader application.

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Other subproject views: All 45 publications 14 publications in selected types All 13 journal articles
Other center views: All 139 publications 42 publications in selected types All 40 journal articles
Type Citation Sub Project Document Sources
Journal Article Steets BM, Holden PA. A mechanistic model of runoff-associated fecal coliform fate and transport through a coastal lagoon. Water Research 2003;37(3):589-608. R828676 (Final)
R828676C003 (2002)
R828676C003 (Final)
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  • Supplemental Keywords:

    bioavailability, transformations, biogeochemistry, selenium, mercury, pesticides, watersheds, estuary, ecological effects, ecosystem indicators, aquatic, integrated assessment, EPA Region 9., RFA, ENVIRONMENTAL MANAGEMENT, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, estuarine research, exploratory research environmental biology, Ecosystem/Assessment/Indicators, Ecosystem Protection, Ecological Effects - Environmental Exposure & Risk, Aquatic Ecosystems, Terrestrial Ecosystems, Ecological Monitoring, Ecological Indicators, Risk Assessment, anthropogenic stresses, ecological risk assessment, wetlands, aquatic ecosystem, bioindicator, anthropogenic stress, biomarkers, ecosystem assessment, estuaries, wetland ecosystem, bioavailability, nutrients, trophic effects, ecosystem indicators, environmental indicators, water quality, coastal ecosystems, ecosystem restoration, aquatic ecology, biogeochemistry

    Progress and Final Reports:

    Original Abstract
  • 2001
  • 2003 Progress Report
  • Final Report

  • Main Center Abstract and Reports:

    R828676    Pacific Estuarine Ecosystem Indicator Research (PEEIR) Consortium

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R828676C000 Pacific Estuarine Ecosystem Indicator Research (PEEIR) Consortium: Administration and Integration Component
    R828676C001 Pacific Estuarine Ecosystem Indicator Research (PEEIR) Consortium: Ecosystem Indicators Component
    R828676C002 Pacific Estuarine Ecosystem Indicator Research (PEEIR) Consortium: Biological Responses to Contaminants Component: Biomarkers of Exposure, Effect, and Reproductive Impairment
    R828676C003 Pacific Estuarine Ecosystem Indicator Research (PEEIR) Consortium: Biogeochemistry and Bioavailability Component