2002 Progress Report: Influence of Invasive Plant Species in Determining Diversity of Aquatic Vegetation in the Mobile-Tensaw Delta

EPA Grant Number: R827072C034
Subproject: this is subproject number 034 , 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: Influence of Invasive Plant Species in Determining Diversity of Aquatic Vegetation in the Mobile-Tensaw Delta
Investigators: Sherman, Timothy , Boettcher, Anne
Institution: University of South Alabama
EPA Project Officer: Packard, Benjamin H
Project Period: August 1, 2001 through December 31, 2002
Project Period Covered by this Report: August 1, 2001 through December 31, 2002
RFA: Alabama Center For Estuarine Studies (ACES) (1999) RFA Text |  Recipients Lists
Research Category: Targeted Research


Introduction of nonindigenous species (NIS) is recognized as one of the leading causes of loss in biodiversity, second only to habitat loss (Walker and Steffen, 1997; Wilcove, et al., 1998). However, the identification of factors that lead to the establishment and persistence of these invaders has remained elusive (Lodge, et al., 1998). The Mobile-Tensaw River Delta, an area rich in species diversity, has not escaped the advance of invasive species. Previous studies have shown that, in certain areas, nonindigenous aquatic plants can dominate in terms of both frequency and biomass (Nelson, 1999). However, the impacts of these species on native plant assemblages and on plant-animal interactions in this system have not previously been examined. The current study and a companion study entitled, "Role of Invasive Species in Shaping Plant-Animal Interactions in the Mobile Delta" were designed to evaluate the role of introduced plant species in shaping plant-animal interactions and plant-plant interactions to elucidate the environmental impacts that NIS may have on the Delta system. The studies focus on NIS currently present in the system, with study sites located in waters surrounding Gravine Island, Baldwin County, AL. The objectives of this research project are to: (1) develop a bioinventory of native and aquatic plant NIS in the waters surrounding Gravine Island; (2) develop a bioinventory of the most common macroinvertebrates found on and around dominant native and introduced aquatic plants in the waters surrounding Gravine Island; and (3) gather data on physiological and growth parameters of dominant native and introduced aquatic plants.

Progress Summary:


The data for the aquatic plant and macroinvertebrate bioinventories have been collected, and the majority of experiments examining plant physiological parameters, including nutrient uptake and photosynthetic capacity, have been conducted. Analyses for plant and animal abundance, diversity, and distribution currently are underway. Preliminary analyses of plant distribution and abundance reveal several patterns. As expected, plant abundance follows seasonal changes in temperature, with peak abundance occurring during the summer season, decreasing with decreasing temperatures. During the first year of sampling, the most common NIS were Alternanthera philoxeroides (alligator weed), Eichhornia crassipes (water hyacinth), and Hydrilla verticillata (Hydrilla). Interestingly, during the second year and third summer of sampling, H. verticillata was the dominant NIS and E. crassipes rarely was detected. There were similar shifts in native species abundance. During the first year, Zizaniopsis miliacea (cut grass), Potamogeton nodosus (longleaf pondweed), and Najas guadalupensis (bushy pondweed) were dominant species at specific sites, but there was no common pattern across sites. However, during the second year and third summer, the dominant natives across sites were Z. miliacea, N. guadalupensis, and Ceratophyllum demersum (coontail).

Preliminary analyses of macroinvertebrate assemblages indicate that gammarid amphipods, small portunid crabs, bivalves in the family Dreissenidae; gastropods in the families Neritinidae, Lymnaeidae, and Planorbidae; damselfly larvae in the family Coenagrionidae; caddisfly larvae in the family Polycentropodidae; and adult coleopteran beetles are common. The results suggest that both invasive and native plant species serve primarily and equally well as habitat for these macroinvertebrates. However, there are differences in the macroinvertebrate distributions among sites. Based on the presence of indicator organisms, including members of the orders Ephemeroptera, Plecoptera, and Trichoptera (otherwise known as EPT), the differences in distribution are thought to be associated with differences in water chemistry.

Analysis of plant growth parameters to date indicates that there are no clear-cut reasons for competitive advantages in NIS. Nutrient uptake experiments indicate that ammonium is the preferred source of the nitrogen by all aquatic species tested. Nitrate, although much more abundant in the water column, is taken up at very low rates, and activity for the first enzyme in the metabolic pathway (nitrate reductase) is very low in all species tested. Although the literature contains a number of references to enhanced growth of invasives such as Hydrilla in nitrate-rich environments, our data do not support this. Uptake rates are slightly higher in the morning than later in the day in a number of species. This appears to be related to diurnal trends in photosynthetic activity. Temperature tolerance may be a more important factor in the success of some species, with both an increase in photosynthetic activity and nutrient uptake at above 30°C. It is likely that success of NIS is related to subtle difference in, or relationships between, physiological parameters. We will be conducting additional experiments and statistical analysis of the data during the duration of the grant to examine these relationships.


Several undergraduates (Lonnie Driskell, Matthew Dawson, Darren Barrett, Anna Penton, Stanislaus Arbaczauskas, Heather Norman, Adrienne Berg, and Savvas Michaelades) have been supported by and/or have conducted research projects associated with this effort. This has provided these students hands-on research experience in both the laboratory and the field. One of the undergraduates supported in the first year of funding, Anna Penton, joined us as a graduate student. Her research focuses on the factors influencing the macroinvertebrate distributions, however, she has assisted with all components of the research. A second student, Stan Arabaczauskas, is using the research skills he gained in his job as an environmental consultant. Recently, a graduate student from the Department of Computer and Information Science, Richa Misra, began assisting with database management and analyses.


Walker B, Steffen W. An overview of the implications of global change for natural and managed terrestrial ecosystems. Conservation Ecology 1997;1(2):2 (http://www.consecol.org/vol1/iss2/art2 Exit ).

Wilcove DS, Rothstein D, Dubow J, Phillips A, Losos E. Quantifying threats to imperiled species in the United States. Bioscience 1998;48:607-615.

Lodge DM, Stein RA, Brown KM, Covich AP, Bronmark C, Garvey JE, Klosiewski SP. Predicting impact of freshwater exotic species on native biodiversity: challenges in spatial scaling. Australian Journal of Ecology 1998;23:53-67.

Nelson DH. Population ecology of the Alabama red belly turtle (Pseudemys alabamensis)—vegetation, diet, clutch size. Final report presented to the Department of Conservation and Natural Resources, December 1999.

Zolczynski J, Shearer R. Mobile Delta submersed aquatic vegetation survey 1994. Presented to the Department of Conservation and Natural Resources, January 1997.

Future Activities:

During the Spring of 2003, analyses for plant and animal abundance, diversity, and distribution will be completed. This data will be paired with data on environmental parameters including light, nutrient levels, and temperature to better understand differences in patterns seen for native and NIS species. Follow-up plant physiological experiments also will be run during the spring of 2003. The graduate student funded by the Small Grant for Exploratory Research (SGER), Anna Penton, is writing a National Aeronautics and Space Administration Graduate Student Research Program grant based on her work with the macroinvertebrates. This grant would fund the analysis and writing phase of her thesis work. The results of these SGERs will serve as a foundation for a larger scale research proposal comparing physiological responses in native and NIS aquatic plants.

Journal Articles:

No journal articles submitted with this report: View all 1 publications for this subproject

Supplemental Keywords:

non-indigenous species, NIS, Alternathera philoxeroides, alligator weed, Eichhornia crassippes, water hyacinth, Hydrilla verticillata, Hydrilla, Zizaniopsis miliacea, cut grass, Potamogeton nodosus, longleaf pondweed, Najas guadalupensis, bushy pondweed, Ceratophyllum demersum, coontail, Neritinidae, Lymnaeidae, Planorbidae, damselfly larvae, Coenagrionidae, caddisfly larvae, Ephemeroptera, Plecoptera, Trichoptera, EPT, coleopteran beetles, Polycentropodidae, ecosystem, ecosystem protection, ecology, ecological effects, ecological indicators, environmental exposure, geographic area, water, water use, aquatic ecosystem, coastal ecosystem, coastal environments, estuary, estuaries, estuarine research, estuarine waters, environmental chemistry, chemistry, risk, assessment, indicators, human health, Alabama, AL, human modifications., RFA, Scientific Discipline, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, estuarine research, Ecology, Aquatic Ecosystems & Estuarine Research, exploratory research environmental biology, Ecosystem/Assessment/Indicators, Ecosystem Protection, Restoration, Aquatic Ecosystem, Ecological Effects - Environmental Exposure & Risk, Aquatic Ecosystems, Terrestrial Ecosystems, Ecological Monitoring, Ecology and Ecosystems, Aquatic Ecosystem Restoration, Ecological Indicators, coastal ecosystem, eutrophication, water use, nursery habitats, estuaries, watersheds, nutrients, pulsed amplitude modulated fluorometry, biomass, fisheries, submerged aquatic vegetation, ecosystem, environmental indicators, water quality, estuarine waters

Relevant Websites:

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

Progress and Final Reports:

Original Abstract
  • 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).
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    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