2002 Progress Report: Investigation of the Use of Pulse Amplitude Modulated (PAM) Fluorometry as an Indicator of Submerged Aquatic Vegetation Health in Mobile Bay

EPA Grant Number: R827072C033
Subproject: this is subproject number 033 , established and managed by the Center Director under grant R827072
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: Alabama Center For Estuarine Studies (ACES)
Center Director: Shipp, Robert L.
Title: Investigation of the Use of Pulse Amplitude Modulated (PAM) Fluorometry as an Indicator of Submerged Aquatic Vegetation Health in Mobile Bay
Investigators: Sherman, Timothy
Institution: University of South Alabama
EPA Project Officer: Packard, Benjamin H
Project Period: June 1, 1999 through December 31, 2001
Project Period Covered by this Report: June 1, 2001 through December 31, 2002
RFA: Alabama Center For Estuarine Studies (ACES) (1999) RFA Text |  Recipients Lists
Research Category: Targeted Research


Beds of submerged aquatic vegetation (SAV) are an important component of estuarine environments, providing habitat for small and juvenile organisms, refuge from predators, and food for estuarine species and migratory waterfowl. The physical structure of SAV serves to remove and trap particulates from the water column and stabilize unconsolidated sediments. Additionally, biological activity and physiological processes of the plants result in improved water quality through the removal and recycling of nutrients, toxins, and other pollutants. Therefore, maintenance of environmental conditions suitable for SAV survival and growth within estuaries is a management goal (Duke and Kruckzynski, 1992).

The objective of this research project focuses on the response of SAV photosynthesis to environmental conditions. This physiological parameter is tightly coupled not only to light conditions, but also to nutrient availability (i.e., dissolved inorganic carbon and nitrogen availability), stress (temperature, ultraviolet-B radiation, etc.), and toxins. In this work, measurements of photosynthetic response were conducted both in the laboratory and in the field using intact tissues.

Progress Summary:

An attempt was made to determine the utility of pulsed amplitude modulated (PAM) fluorometry to ascertain the physiological state and to evaluate environmental conditions that maximize photosynthetic efficiency of two native SAVs (Tapegrass [Vallisneria americana] and Coontail [Ceratophyllum demersum]) and two commonly introduced species (Eurasian water milfoil [Myriophyllum spicatum] and Hydrilla [Hydrilla verticilata]) under field conditions. This work will produce baseline data on photosynthetic parameters for aquatic SAV found in the Mobile-Tensaw River and other southeastern waterways.

Specific accomplishments include:

(1) PAM measurements were compared with those generated by polarigraphic measurements (using an analytical Clark-type oxygen electrode) under field conditions.

(2) Measurements taken in the field were compared to those taken on similar tissues transported back to the laboratory using conditions that have been utilized in previous reports.

(3) PAM, oxygen electrode data from different tissues of the same plants (e.g., young versus old leaves, young versus old parts of the same leaf), and similar tissues during the course of the growing season were compared.

(4) The effects of salinity and dissolved nutrient concentrations also were examined.


Data collected indicate that PAM fluorometry and polarigraphic measurements of photosynthetic oxygen production yield comparable results in the field and in the laboratory. The relationship between electron transport rate (measured by PAM) and oxygen evolution (corrected for dark respiration) was linear in Hydrilla but not in Vallisneria, suggesting possible photorespiratory activity in the latter species. Measured photosynthetic capacity markedly changed when tissues were transported back to the laboratory prior to assay, indicating that measurements made in the field may be more relevant for judging competitive differences between species.

In all species examined, photosynthetic capacity, measured as oxygen evolution or PAM fluorescence, showed a great deal of variability on different areas of the leaf, between leaves of different ages, and between different plants. Often, highest activity was found in the youngest, fully expanded tissue, with slightly lower activity in the youngest tissue, and lowest activity in the older portions. This trend also was true for individual leaves of V. americana, with lowest activity found toward the leaf tips. This trend has been reported for the marine SAV Thalassia testudinum, which has similar morphology (Durako and Kunzelman, 2002). The youngest, fully mature leaves are probably the best candidates for analyses. A dark adaptation period of 5 minutes was sufficient to open all photosystem (PS) reaction centers with all species examined and was used to determine all maximum quantum yields.

Tissues assayed in the field, measured with both techniques, had photosynthetic capacities that varied during the course of the day, with peak activities occurring early in the day and decreased activities occuring in the early afternoon. This is consistent with recent work (Beer and Bork, 2000: Durako, et al., 2002). Photosynthetic capacity of a given species was generally constant until late in the growing season, when tissues began to senesce, or at higher temperatures during the warmest months. Hydrilla tolerated higher light intensities and higher temperatures than did Vallisneria.

Increasing salinity had a negative effect on all plants, but at levels normally experienced by these plants, little adverse effect was noted.


Several undergraduates (Matthew Dawson, Anna Penton, Stanislaus Arbaczauskas, and Savvas Michaelades) have been involved in this research project. This has provided these students with hands-on research experience in both the laboratory and in the field. Anna Penton, one of the undergraduates supported in the first year of funding, joined us as a graduate student. Although her research focuses on the factors influencing the macroinvertebrate distributions, she has assisted with all components of the research. A second student, Stan Arabaczauskas, is using the research skills he gained on this project in his work as an environmental consultant.


Duke T, Kruczynski WL. Status and trends of emergent and submerged vegetated habitats, Gulf of Mexico, USA. Report of the U.S. Environmental Protection Agency Gulf of Mexico Program Habitat Degradation Subcommittee. U.S. Environmental Protection Agency, Office of Water, EPA 800-R-92-003, 1992, p. 161.

Durako MJ, Kunzelman JI. Photosynthetic characteristics of Thalassia testudinum measured in situ by pulse-amplitude modulated (PAM) fluorometry: methodological and scale-based considerations. Aquatic Botany 2002;73(2):173-185.

Beer S, Björk M. Measuring rates of photosynthesis of two tropical seagrasses by pulse amplitude modulated (PAM) fluorometry. Aquatic Botany 2000;66(1):69-76.

Future Activities:

Future activities are planned for the spring of 2003. Some additional experiments will be performed and analyses will be completed. This data will be paired with data on environmental parameters, including light, nutrient levels, nutrient uptake capacity, and temperature to better understand different patterns seen for native and nonindigenous species (NIS). Data from this work will be interpreted within the context of other Alabama Center for Estuarine Studies exploratory research projects being conducted in our laboratory. The results of these Small Grants for Exploratory Research will serve as a foundation for a larger-scale research project comparing physiological responses in native and NIS aquatic plants.

Supplemental Keywords:

submerged aquatic vegetation, SAV, photosynthesis, Pulsed Amplitude Modulated, PAM, tapegrass, Vallisneria americana, coontail, Ceratophyllum demersum, Eurasian water milfoil, Myriophyllum spicatum, Hydrilla, Hydrilla verticilata, photosynthetic oxygen, electron transport rate, oxygen evolution, Thalassia testudinum, ecosystem, ecosystem protection, ecology, ecological effects, ecological indicators, environmental exposure, geographic area, water, aquatic ecosystem, coastal ecosystem, coastal environments, estuary, estuaries, estuarine research, estuarine waters, environmental chemistry, chemistry, risk, assessment, indicators, Alabama, AL, human modifications, fishery sampling., RFA, Scientific Discipline, ECOSYSTEMS, Water, Ecosystem Protection/Environmental Exposure & Risk, Aquatic Ecosystems & Estuarine Research, Ecology, estuarine research, Ecosystem/Assessment/Indicators, Ecosystem Protection, exploratory research environmental biology, Restoration, Aquatic Ecosystem, Aquatic Ecosystems, Terrestrial Ecosystems, Ecological Monitoring, Ecology and Ecosystems, Ecological Risk Assessment, Aquatic Ecosystem Restoration, coastal ecosystem, eutrophication, nursery habitats, water use, estuaries, watersheds, pulsed amplitude modulated fluorometry, nutrients, biomass, fisheries, submerged aquatic vegetation, ecosystem, environmental indicators, estuarine waters, water quality, human modifications

Relevant Websites:

http://www.southalabama.edu/aces/ Exit
http://www.invasivespecies.gov/ Exit

Progress and Final Reports:

Original Abstract
  • 1999
  • 2000
  • Final

  • Main Center Abstract and Reports:

    R827072    Alabama Center For Estuarine Studies (ACES)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R827072C001 Fluorescent Whitening Agents As Facile Pollution Markers In Shellfishing Waters
    R827072C002 Red Snapper Demographics on Artificial Reefs: The Effect of Nearest-Neighbor Dynamics
    R827072C003 Stabilization of Eroding Shorelines in Estuarine Wave Eliminates with Constructed Fringe Wetlands Incorporating Offshore Breakwaters
    R827072C004 Interaction Between Water Column Structure and Reproduction in Jellyfish Populations Of Mobile Bay (SGER)
    R827072C005 Effects of Variation in River Discharge and Wind-Driven Resuspension on Higher Trophic Levels in the Mobile Bay Ecosystem
    R827072C006 Results of Zooplankton Component
    R827072C007 Benthic Study Component
    R827072C008 A Preliminary Survey of Macroalgal and Aquatic Plant Distribution in the Mobile Tensaw Delta
    R827072C009 Fisheries-induced changes in the structure and function of shallow water "nursery habitats": an experimental assessment
    R827072C010 Effects Of Variation in River Discharge and Wind-Driven Resuspension on Lower Trophic Levels of the Mobile Bay Ecosystem
    R827072C011 Evaluation of Alabama Estuaries as Developmental Habitat for Juvenile Sea Turtles
    R827072C012 Effects of Salinity Stress on Natural and Anthropogenically-Derived Bacteria in Estuarine Environments
    R827072C013 The Role of Land-Use/Land-Cover and Sub-estuarine Ecosystem Nitrogen Cycling in the Regulation of Nitrogen Delivery to a River Dominated Estuary; Mobile Bay, Alabama
    R827072C014 Environmental Attitudes of Alabama Coastal Residents: Public Opinion Polls and Environmental Policy
    R827072C015 Synthesis and Characterization of an Electrochemical Peptide Nucleic Acid Probe
    R827072C016 Determinants of Small-Scale Variation in the Abundance of the Blue Crab Callinectes Sapidus
    R827072C017 Effects of Estrogen Pollution on the Reproductive Fitness of the Gulf Pipefish, Syngnathus scovelli
    R827072C019 A Model for Genetic Diversity Aquatic Insects of the Mobile/Tensaw River Delta
    R827072C020 Evaluating Trophic Processes as Indicators of Anthropogenic Eutrophication in Coastal Ecosystems: An Exploratory Analysis
    R827072C021 Effects of Anthropogenic Eutrophication on the Magnitude and Trophic Fate of Microphytobenthic Production in Estuaries
    R827072C022 Characteristics of Ship Waves and Wind Waves in Mobile Bay
    R827072C023 Methods Comparison Between Stripping Voltammetry and Plasma Emission Spectroscopy for Metals in Mobile Bay
    R827072C024 Changes in Water Conditions and Sedimentation Rates Associated With Construction of the Mobile Bay Causeway
    R827072C025 Cold-Induced Hibernation of Marine Vibrios in the Gulf of Mexico: A Study of Cell-Cell Communication and Dormancy in Vibrio vulnificus
    R827072C026 Holocene Sedimentary History of Weeks Bay, AL: Human and Natural Impacts on Deposition in a Gulf Coast Estuary
    R827072C027 Shelter Bottlenecks and Self-Regulation in Blue Crab Populations: Assessing the Roles of Nursery Habitats and Juvenile Interactions for Shelter Dependent Organisms
    R827072C028 Predicting Seagrass Survival in Nutrient Enriched Waters: Toward a New View of an Existing Paradigm
    R827072C029 DMSP and its Role as an Antioxidant in the Salt Marsh Macrophyte Spartina alterniflora
    R827072C030 A Preliminary Survey of Aerial and Ground-Dwelling Insects of the Mobile/Tensaw Delta
    R827072C031 Natural Biogeochemical Tags of Striped Mullet, Mugil cephalus, Estuarine Nursery Areas in the North Central Gulf of Mexico
    R827072C032 Resolution of Sedimentation Rates in Impacted Coastal Environments Using 137Cs and 210Pb Markers: Dog River and Fowl River Embayments
    R827072C033 Investigation of the Use of Pulse Amplitude Modulated (PAM) Fluorometry as an Indicator of Submerged Aquatic Vegetation Health in Mobile Bay
    R827072C034 Influence of Invasive Plant Species in Determining Diversity of Aquatic Vegetation in the Mobile-Tensaw Delta
    R827072C035 The Influence of Shallow Water Hydrodynamics on the Importance of Seagrass Detritus in Estuarine Food Webs
    R827072C036 Food Web Interactions, Spatial Subsidies and the Flow of Energy Between the Mobile Bay Delta and Offshore Waters: A SGER Proposal to the Alabama Center for Estuarine Studies
    R830651C001 Meteorological Modeling of Hurricanes and Coastal Interactions: A Stability Study For Vertical Pressure Levels
    R830651C002 Characterization of Glycoprotein Cues Used by the Parasitic Rhizocephalan Barnacle Loxothylacus texanus To Identify Its Blue Crab Host, Callinectes sapidus
    R830651C003 Survey of Diamondback Terrapin Populations in Alabama Estuaries
    R830651C004 An Assessment of Environmental Contaminant Levels in Water and Dragonfly Larvae Tissues from the Mobile/Tensaw Delta