AMRAT 2004
Alabama - Mississippi Rapid Assessment Team

Survey of Problem Aquatic Plant Species

Mississippi Coastal Waters "Most-Wanted" Aquatic Plant Species

Section Scientific Name Common Name

  1. Alternanthera philoxeroides Alligator Weed
    This nuisance aquatic plant can clog waterways and interfere with navigation and water flow. Alligator weed was introduced from South America in association with shipping (possibly ballast water) through the Port of Mobile, AL, in 1897.
  2. Colocasia esculenta Wild Taro
    A food plant in the Pacific islands, taro can be toxic to animals. Cooking or fermentation removes the toxin, calcium oxalate, which irritates the skin. Introduced through horticultural trade, it can shade aquatics and displace native wetland margin plants.
  3. Eichhornia crassipes Water Hyacinth
    This Amazonian native from Brazil , introduced in New Orleans as a decorative pond plant in 1884, chokes waterways, shades native aquatics, and reduces water quality. It can interfere with the normal feeding patterns of waterfowl and water dependent wildlife.
  4. Egeria densa Brazilian Elodea
    Introduced from Brazil through the aquarium trade, this submersed plant was first documented in U.S. waters in 1893, and has since naturalized throughout most states. Concerns include habitat alteration and interference with boating activities.
  5. Hydrilla verticillata Hydrilla; Water-thyme
    This African aquatic plant, introduced through the aquarium trade in 1960, replaces native aquatic plants and provides excellent habitat for mosquitoes. It is one of the most aggressive aquatic invasive plants.
  6. Hygrophila polysperma Hygrophila; Indian Swampweed
    An aquarium plant imported from the East Indies in 1945, this plant was first collected in the wild near Tampa , FL , in 1965, and has spread as far north as the Florida panhandle. It is also reported to occur in Texas and Virginia . Replacement of native submerged vegetation is the primary concern with this species, along with decreased water quality.
  7. Limnophila sessiliflora Limnophila; Asian Marshweed; Ambulia
    Native to India and southeast Asia, this aquatic plant was introduced through the aquarium trade in 1961 near Tampa , and shortly thereafter in Texas and Georgia . It has become established in those states, and is officially listed as a noxious aquatic weed or prohibited from importation. It replaces native submerged aquatic plants.
  8. Lythrum salicaria Purple Loosestrife
    This perennial ornamental plant was introduced from Europe and Asia to Canada and the northeastern U.S. in the early 1800s for medicinal uses. It was once prized as a treatment for dysentery and diarrhea. It can rapidly replace native wetland vegetation.
  9. Myriophyllum aquaticum Parrot Feather
    An aquarium trade introduction from the Amazon, this submerged aquatic plant was documented as an introduced species during the late 1800s in the Washington , D.C. area, and has spread throughout U.S. coastal states. It replaces native aquatics, alters habitat, and degrades water quality.
  10. Myriophyllum spicatum Eurasian Watermilfoil
    Introduced in the early 1900s via aquarium and pond plant trades in the vicinity of Washington , D.C. and Chesapeake Bay , this native of Europe , Africa , and east Asia shades out native aquatics. It also interferes with boating and swimming, provides prime mosquito habitat, and can clog water intakes.
  11. Najas marina Spinyleaf or Spiny Naiad; Holly-leaf Naiad
    This potential nuisance species, native to parts of Texas and Florida , can interfere with boating and swimming. It could replace more desirable local native aquatic plants, altering habitat and species distributions of fish and invertebrates.
  12. Nasturtium officinale Watercress
    (Rorippa nasturtium aquaticum)
    Introduced in the 1700s to bog habitats from water gardens, this European plant has naturalized in most U.S. states. It is used as a culinary herb and in folk medicine for treatment of stomach aches and sore throats. It chokes streams, and is considered an exotic aquatic pest, particularly in areas where native animals can not eat it as a food.
  13. Nelumbo nucifera Sacred Lotus
    Native to south Asia and Australia , and referenced in Homer’s Odyssey, this pond plant is cultivated as an ornamental pond plant and for Chinese medicinal uses. In areas of the southeastern U.S. where it has escaped, it can replace native water lilies and other submerged aquatic vegetation, altering habitat and water quality, plus changing the types of animals found in surrounding water and sediment.
  14. Panicum repens Torpedo Grass
    Reportedly introduced from Australia , this rapidly growing, aggressive grass occurs along the borders of the Gulf of Mexico and chokes out other native species, particularly dune plants. It can interfere with water movement in ditches and canals, and limit recreational use of beach and shoreline areas.
  15. Pistia stratiotes Water Lettuce
    Possibly introduced from the ballast water of explorer’s ships, this floating plant was documented as a pest plant in 1774, clogging portions of waterways in Florida . It blocks sunlight, displaces other aquatic plants, and negatively affects habitat and water quality.
  16. Potamogeton crispus Curlyleaf Pondweed
    This aquatic plant, native to Europe and Asia , was introduced along U.S. coastlines in the mid 1800s. It has spread throughout the U.S. , possibly in water used to transport fish. It restricts water flow and recreational water access, and alters habitat and water quality.
  17. Salvinia molesta Giant Salvinia
    Extremely prolific and invasive, this floating plant can double its numbers in 2-10 days. Imported through pond and aquarium trade from southeastern Brazil , this plant is now illegal to possess or sell. First documented in the wild in 1995 in South Carolina , where it was eradicated; it has appeared in the wild in a number of locations, most recently in July 2004 in coastal waters of Texas .
  18. Stratiotes aloides Water Aloe
    This noxious aquatic weed, also referred to as “water-soldier” or “crab’s claw”, is native to Europe . A floating aquatic plant, it can quickly spread, shade, and replace native aquatic vegetation. Left uncontrolled, it may become the next “water hyacinth”.

“Terrestrial” Aquatic Iinvasive Plants

These species grow at wetland and waterway margins and alter/convert habitat from wetlands and savannahs to uplands. They also out-compete and replace native plant species.

  1. Imperata cylindrica Cogon grass
    Introduced through the Port of Mobile in 1912 as packing material used in shipping, this salt tolerant east Asian grass spreads rapidly in disturbed areas, and replaces native grasses and plants in habitats ranging from sand dunes to pine savannahs and swamps. It is extremely difficult to eradicate once established.
  2. Triadica sebifera (Sapium sebiferum) Chinese tallow tree
    Originating in China , where it was used for seed oil production, this prolific tree has spread to all coastal states since its 1772 introduction as an ornamental in Charleston , SC reportedly by Benjamin Franklin. It replaces native wild plants, degrading water quality by producing more leaf litter and seeds than the native plant species it replaces.
  3. Lonicera japonica Japanese honeysuckle
    This East Asian plant, naturalized in the eastern and central U.S. , was introduced in 1864 as a horticultural cultivar. It shades native plant species, alters habitat, and can topple trees from its weight in areas of dense growth, blocking waterways.

Sampling Protocol

Botanical components of AMRAT

Both indigenous and nonindigenous plants and macroalgae will be documented at selected sites in marine and estuarine areas of Mississippi Sound . The field survey component of the rapid assessment will use three replicate samples from each site, with species identified to the lowest taxonomic level and recorded as either absent or present, along with an index of abundance (rare, common, abundant or dominant). Any unknown taxa will be collected for later identification by plant experts. Samples of abundant species may also be collected for future use in identification/verification if there are questions regarding taxonomy, or if the species is believed to be under-represented in existing plant collections (i.e., herbaria).

Targeted sampling locations consist of locations where the potential for introduction of invasive species is high; examples would be port areas, high boat traffic areas, sites with potential for contamination or introduction of species through ballast water releases, and mouths of bayous and rivers or embayments (species introductions via surface waters). Areas of concern that may also be a focus for sampling are wildlife management areas where invasive species could potentially become a major problem if not detected. The Alabama sampling event (September 2003) included roughly 50 plant sampling stations:

(1) phytoplankton samples from the waters around two offshore oil rigs and the Mobile Bay Light, collected in duplicate; samples consisted of 10 liters of surface water passed through a 10 micron mesh plankton net, which were checked in the laboratory for presence or absence of harmful algae;

(2) shorelines from just north of I-10 (tidal fresh) to coastal bays and locations to the east and west of the mouth of Mobile Bay , plus waterways and heavy use boat launches were assessed by recording the presence/absence of native vascular flora and invasive species.

Sampling stations were defined as the area within a 3-meter arc from the GPS position of the sampling vessel for the 2003 event; this allowed both wetlands/terrestrial margins and submerged aquatic habitats to be included in the assessment. Hard substrates adjacent to stations were also sampled to allow macroalgae to be included in the overall assessment.

Water quality data were collected at all sampling locations. Parameters measured at the water surface, mid-depth and bottom included depth, temperature, salinity, and dissolved oxygen. Other information recorded included station number, sample collectors, date, time, gear, sea state, cloud cover, wind speed and direction, and latitude and longitude.

Similar sampling plans are anticipated for use in assessing Mississippi Sound and adjacent waters.

Equivalent water quality data should also be collected. There are a series of MDEQ water quality sampling stations that have existing data sets which may be available for reference purposes.

Potential Sampling Locations - AMRAT Mississippi


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West Mississippi Sound ( Hancock County )

Central Mississippi Sound ( Harrison County )

East Mississippi Sound ( Jackson County )

This is a preliminary suggested list; please add (or remove) sampling locations. Bear in mind that our primary goal is to document the resident and introduced flora in any areas where the presence of invasive species is likely, and that our focus in on aquatic and wetland habitats.

Note: A fauna oriented sampling crew plans to target the western portion of Mississippi Sound (west of Gulfport Ship Channel) prior to the scheduled sampling period from 30 Aug-3 Sept.

Source: Cynthia Moncrieff, Gulf Coast Research Lab, Univ. of South Mississippi