2004 Progress Report: Environmental Indicators in the Estuarine Environment: Seagrass Photosynthetic Efficiency as an Indicator of Coastal Ecosystem Health

EPA Grant Number: R828677C004
Subproject: this is subproject number 004 , established and managed by the Center Director under grant R828677
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: EAGLES - Atlantic Coast Environmental Indicators Consortium
Center Director: Paerl, Hans
Title: Environmental Indicators in the Estuarine Environment: Seagrass Photosynthetic Efficiency as an Indicator of Coastal Ecosystem Health
Investigators: Kenworthy, Judson , Fonseca, Mark , Gallegos, Charles L. , Snyder, Richard , Thursby, G.
Current Investigators: Fonseca, Mark , Biber, Patrick , Field, Donald , Gallegos, Charles L. , Kenworthy, Judson , Thursby, G.
Institution: University of North Carolina at Chapel Hill
Current Institution: National Oceanic and Atmospheric Administration (NOAA) , University of North Carolina at Chapel Hill
EPA Project Officer: Hiscock, Michael
Project Period: March 1, 2001 through February 28, 2003
Project Period Covered by this Report: March 1, 2003 through February 28, 2004
RFA: Environmental Indicators in the Estuarine Environment Research Program (2000) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Water , Ecosystems


The objectives of this research project are to:

  1. evaluate indicators of seagrass health and their role in estuarine processes;
  2. examine physiological state of seagrass in response to environmental conditions (light, temperature, salinity) and correlate the plant’s physiological state with ambient conditions based on both in situ and remote sensed data sources;
  3. and evaluate techniques of scaling field assessments to remote sensed data sources.

Progress Summary:

Light availability to benthic seagrasses has been determined to be the major criterion limiting the distribution of seagrass in otherwise appropriate conditions. We initiated a monthly water-sampling program in North River, North Carolina, in September 2002, and this was completed with 2 years of data in September 2004. Water samples are analyzed for absorption and scattering properties, and these are related to components of attenuation: chlorophyll, turbidity, and color. Data continue to be analyzed in collaboration with C. Gallegos at the Smithsonian Environmental Research Center (SERC).

Ongoing sampling of water quality in both North River and Pamlico Sound occurred through September 2004 to parameterize the bio-optical model created by C. Gallegos. A total of 180 water samples were collected from 9 sites in the North River (Figure 1), around beds of the seagrass, Zostera marina, for the purpose of generalizing the bio-optical indicator model. Another 108 samples were collected from 9 stations in Pamlico Sound. Cooperative efforts between the Atlantic Slope Consortium (ASC) and the Atlantic Coast Environmental Indicators Consortium (ACE-INC) Estuarine and Great Lakes (EaGLes) projects are now being undertaken to develop a regionally extensive atlas of optical properties for broad geographic application of this indicator.

Figure 1. Selected Results From Monthly Water-Quality Monitoring Program in North River. Time-Space contour plots of temperature, salinity, chlorophyll-a (Chl-a) concentration, and turbidity (NTU) measured monthly from Sept 2002 to Apr 2004. Sites are numbered from downstream (1) to most upstream (9).

In support of the bio-optical indicator development, we determined the depth limits of three decade stable Zostera beds in North River, to test and refine predictions of the model. The depth measurements were made using the Differential GPS Phase-Carrier technique, which used a base station at Harkers Island on a geodetic benchmark and two roving GPS units in the field (Figure 2). Vertical precision was less than 5 cm. Depth of the deep-edges of the seagrass beds agreed to within 10 cm of the model predictions.

Figure 2. One of the Rover D-GPS Units at a Seagrass Bed in North River, September 2004

We continued testing and development of the RopeAssay Method for use in water-quality assessments for seagrass (SAV) suitability. Two deployments were completed for 2004, one in March/April using Zostera and a second in August/September using Halodule. Concurrent with both seagrass deployments, we collaborated with R. Snyder of the University of Western Florida to deploy his biofilm collectors (Figure 2). Dr. Snyder brought up two of his graduate students (Matt Wagner and Tanya Panteleimonova) to assist with these deployments and learn HPLC and other techniques at the Paerl laboratory.

Figure 3. Biofilm Collectors for Benthic and Surface Samples and YSI Deployment for Water Quality Data in March 2004

Two experiments in the National Oceanic and Atmospheric Administration (NOAA) greenhouse facility were conducted to determine the importance of timing and duration of light attenuation events (e.g., turbidity plumes/extreme phytoplankton blooms) on seagrass survival. These experiment compared the responses of Zostera seedlings (2-3 months old) against adults of the same species (> 1 year) in spring and against Halodule, a second ubiquitous seagrass species in the summer. Results indicate that stress:recovery time needs to be no less than 1:1 for seagrass survival.

Background. A healthy community of underwater plants known as seagrasses is essential for healthy estuarine ecosystems such as Pamlico Sound. These marine plant communities provide food for waterfowl and shelter for numerous important shellfish, invertebrates, and fish. Ecosystem services provided by seagrasses abound. Microscopic algae living on the grass blades are the base of a food chain that cascades up to shrimp, blue crabs, red drum, croaker, flounder, menhaden, and a myriad of other valuable fish species. Seagrass meadows help stabilize bottom sediments, provide a protective nursery for many aquatic organisms, and are a key food source for migratory waterfowl.

Ecological Indicator. Seagrasses are a sensitive indicator of declining water quality because of their high light requirements. Researchers at University of North Carolina-Chapel Hill (UNC-CH) and NOAA-Beaufort Laboratory, in collaboration with SERC (ASC), have tested and applied a bio-optical model based on total suspended solids and algal chlorophyll for monitoring the optical properties of the water column in Pamlico Sound. These procedures have produced a diagnostic tool for setting water quality targets for seagrass protection in North Carolina. In addition, this research has suggested new ideas on the mechanisms by which increasing eutrophication may be altering water column optical properties to the detriment of aquatic organisms.

Ecological Effect/Impact. Seagrasses need relatively high amounts of light. Decreased light penetration limits the growth and distribution of seagrasses. Turbidity, chlorophyll, and color are natural contributors to decreased light penetration with increasing depth; however, increases in sediment from development on the land and increases in nutrients (eutrophication) in the water lead to coatings on the seagrass leaves and to algal blooms, which both block light and can ultimately kill the plants.

Environmental Application. State and federal watershed managers in North Carolina are using this tool to make management decisions on reducing suspended solids and chlorophyll as part of the new Coastal Habitat Protection Plan designed, in part, to protect seagrasses in North Carolina estuaries. Ongoing development and implementation of real-time operational indicators of water quality with relevance to seagrasses will further create tools for management agencies. These are software-based implementations of an expert-system that relies on the knowledge developed in this project and will be a tool that is available to resource managers to assist in the setting of relevant total maximum daily loads to protect SAV resources.

Training and Educational Development

Two interns were mentored over the past year. Teresa P. Denault of Eastern Carteret High School was working at the Institute of Marine Sciences (IMS) for the summer. She returned for this additional internship after interning in fall 2003. She is going to college to major in biological sciences at UNC-CH. Napoleon Paxton of Elizabeth City State University (ECSU) interned for the summer at the NOAA-Beaufort Laboratory. He worked on GIS-related activities to create maps of the water quality data from North River and animations for data analysis. In addition, he started on a project to create a mapping tool for identifying thresholds in water quality (i.e., making the optical model spatially and temporally dynamic). He presented the results of this research at the IEEE Geoscience and Remote Sensing Distinguished Lecture Series at ECSU.

Outreach Activities

Dr. Biber commenced the monitoring of SAV before the impacts in a local coastal construction project at Carteret Community College. This included a subcontract to a local small business (Geodynamics, Inc.) for high resolution mapping of the bathymetry at the site using multibeam sonar.

Drs. Kenworthy and Biber successfully obtained an memorandum of agreement between NOAA-Beaufort Laboratory and Massachusetts Department of Environmental Protection (DEP) to undertake an assessment of water-quality issues causing declines of seagrasses in Massachusetts. This project will make extensive use of the bio-optical modeling framework developed under ACE-INC. A workshop will be held March 30-31, 2005, in Falmouth, Massachusetts, with about 30 participants from DEP and 6 invited guest speakers.

Dr. Biber successfully completed his post-doctoral activities in November 2004 and started a tenure-track position as assistant professor at the University of Southern Mississippi’s Gulf Coast Research Laboratory in the Department of Coastal Sciences, where he is now the head of the marine botany section.


Bio-optical Modeling Pamphlet – distributed at numerous State Agency and National meetings.

Seagrass CriteriaBase software Beta v1.0. This runs as an add-in under Microsoft Windows.

Future Activities:

We will conduct a pilot project to assess PAR (Photosynthetically Available Radiation) versus PUR (Photosynthetically Usable Radiation) along a latitudinal gradient in water quality from Chesapeake Bay to Belize. This is a collaboration with C.L. Gallegos at SERC. The Belize portion of this project was completed in January 2005.

We will further refine leaf reflectance data as a non-invasive, non-destructive measure of chlorophyll content. This will provide the first data on this approach for both Zostera and Halodule species. Dr. Biber will be traveling to University of Rhode Island to discuss methods to analyze this data with Dr. Mike Traber in April 2005.

Journal Articles on this Report : 4 Displayed | Download in RIS Format

Other subproject views: All 37 publications 7 publications in selected types All 6 journal articles
Other center views: All 383 publications 99 publications in selected types All 88 journal articles
Type Citation Sub Project Document Sources
Journal Article Biber PD, Snedaker SC. Measuring the effects of salinity stress in the Red Mangrove, Rhizophora Mangle L. Journal of Experimental Marine Biology and Ecology (submitted, 2005). R828677C004 (2004)
not available
Journal Article Biber PD. Hydroponic versus rooted growth of Zostera marina L. (Eelgrass). Hydrobiologia 2006;568(1):489-492. R828677 (Final)
R828677C004 (2004)
  • Abstract: SpringerLink-Abstract
  • Journal Article Gallegos CL, Biber PD. Diagnostic tool help set water quality targets for restoring submerged aquatic vegetation in Chesapeake Bay. Ecological Restoration 2004;22(4):1441-1451 R828677C004 (2004)
    R828684C002 (2004)
    not available
    Journal Article Irlandi EA, Orlando BA, Biber PD. Drift algae-epiphyte-seagrass interactions in a subtropical Thalassia testudinum meadow. Marine Ecology-Progress Series 2004;279:81-91. R828677C004 (2004)
    R828677C004 (Final)
    not available

    Supplemental Keywords:

    seagrass, bio-optics, nutrients, bioindicators, conservation, environmental assets, scaling, aquatic, habitat, estuary, coastal, regionalization, integrated assessment, restoration, water quality and habitat management, remote sensing,, RFA, Scientific Discipline, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, RESEARCH, estuarine research, Ecosystem/Assessment/Indicators, Ecosystem Protection, Ecological Effects - Environmental Exposure & Risk, Monitoring, Environmental Monitoring, Ecological Monitoring, Ecological Risk Assessment, Ecology and Ecosystems, Ecological Indicators, bioassessment, bioindicator, ecoindicator, remote sensing, aquatic biota , indicator plants, diagnostic indicators, ecosystem indicators, estuarine ecoindicator, estuarine ecosystems, aquatic ecosystems, environmental indicators, estuarine waters, seagrass photosynthesis, water quality, biogeochemistry, bio-optics, environmental stress indicators

    Relevant Websites:

    http://www.aceinc.org Exit
    http://www.usm.edu/gcrl/research/seagrass_indicators.php Exit

    Progress and Final Reports:

    Original Abstract
  • 2001
  • Final Report

  • Main Center Abstract and Reports:

    R828677    EAGLES - Atlantic Coast Environmental Indicators Consortium

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R828677C001 Phytoplankton Community Structure as an Indicator of Coastal Ecosystem Health
    R828677C002 Trophic Indicators of Ecosystem Health in Chesapeake Bay
    R828677C003 Coastal Wetland Indicators
    R828677C004 Environmental Indicators in the Estuarine Environment: Seagrass Photosynthetic Efficiency as an Indicator of Coastal Ecosystem Health