Salvinia molesta - Mitchell
Giant Salvinia
Other English Common Names: African Pyle, Aquarium Watermoss, Kariba-weed, Koi Kandy, Water Fern, Water Velvet
Other Common Names: kariba-weed
Taxonomic Status: Accepted
Related ITIS Name(s): Salvinia molesta Mitchell (TSN 181823)
Unique Identifier: ELEMENT_GLOBAL.2.144289
Element Code: PPSAL01030
Informal Taxonomy: Plants, Vascular - Ferns and relatives
 
Kingdom Phylum Class Order Family Genus
Plantae Filicinophyta Filicopsida Salviniales Salviniaceae Salvinia
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Salvinia molesta
Taxonomic Comments: Considered exotic in North America (23 Mar 94)
Conservation Status
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NatureServe Status

Global Status: GNR
Global Status Last Reviewed: 11Sep2002
Global Status Last Changed: 11Sep2002
Rounded Global Status: GNR - Not Yet Ranked
Nation: United States
National Status: NNA

U.S. & Canada State/Province Status
United States Alabama (SNA), Florida (SNA), Georgia (SNA), Louisiana (SNA), North Carolina (SNA), Texas (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Escaped as an exotic in the U.S. in Texas, Louisiana, Alabama, Florida (Kartesz 1999), and Georgia (Georgia Natural Heritage Program, July 2000).

Other NatureServe Conservation Status Information

Distribution
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Global Range: Escaped as an exotic in the U.S. in Texas, Louisiana, Alabama, Florida (Kartesz 1999), and Georgia (Georgia Natural Heritage Program, July 2000).

U.S. States and Canadian Provinces
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States ALexotic, FLexotic, GAexotic, LAexotic, NCexotic, TXexotic

Range Map
No map available.

Ecology & Life History
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Habitat Comments: Aquatic.
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank)
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Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: Medium
Rounded I-Rank: Medium
I-Rank Reasons Summary: This free-floating aquatic fern is a sterile hybrid that spreads solely by vegetative growth and fragmentation. It's rapid growth and tolerance to environmental stress makes it an aggressive, competitive species known to impact aquatic environments. It currently is established in at least six states across the US, but is expected to expand its range. Management of this species can be achieved through biocontrol using the weevil, Cyrtobagous salviniae.
Subrank I - Ecological Impact: Medium
Subrank II - Current Distribution/Abundance: Medium
Subrank III - Trend in Distribution/Abundance: High
Subrank IV - Management Difficulty: Unknown
I-Rank Review Date: 14Apr2004
Evaluator: Lu, S.
Native anywhere in the U.S?
Native Range: Native to southeastern Brazil, between latitudes of 24 and 32 degrees S, especially abundant along coastal Brazil, extending inland to elevations of 900 m (Jacono, no date).

Download "An Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity". (PDF, 1.03MB)
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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: This species is a non-native that is established outside of cultivation (Kartesz 1999).

S-2. Present in conservation areas or other native species habitat? Yes
Comments: Poses a serious threat to lakes, ponds, streams, rivers and other freshwater wetlands, and cultivated rice fields in the US(Swearingen et al. 2002).

Subrank I - Ecological Impact: Medium

1. Impact on Ecosystem Processes and System-wide Parameters:Moderate significance
Comments: Forms dense mats that may competely cover the water surface and become up to 1 m thick and subsequently affect the water flow, reduce oxygen levels (Weber 2003), and reduce system-wide light availability to other plants. Dead plants release large amounts of nutrients into the water, and increases eutrophication (Weber 2003). Resulting dense surface cover prevents light and atmospheric oxygen from entering the water. Decomposing material drops to the bottom and greatly consumes dissolved oxygen needed by fish and other aquatic life. (Jacono 2003)

2. Impact on Ecological Community Structure:High significance
Comments: Forms dense mats of tightly packed leaves as large as 96 square miles in area and up to 3 feet deep and eliminates all submerged native vegetation that is so important to the fish. (USACE, no date)

3. Impact on Ecological Community Composition:High significance
Comments: Forms dense mat that shade and overcrowd native aquatic plants (Jackman 2003). Degrades water quality for fish and other aquatic organisms (Swearingen et al. 2002). Eliminates all submerged native vegetation that is so important to the fish (USACE, no date).

4. Impact on Individual Native Plant or Animal Species:Insignificant
Comments: No reported impacts.

5. Conservation Significance of the Communities and Native Species Threatened:Insignificant
Comments: No reported impacts.

Subrank II. Current Distribution and Abundance: Medium

6. Current Range Size in Nation:Low significance
Comments: Established in waterbodies in freshwater drainages of Texas and Louisiana, Alabama, Georgia, Florida, Mississippi, Arizona, California, and Hawaii (Jacono, no date). However Kartesz (1999) only acknowledges the establishment of this species in six states, including Alabama, Florida, Hawaii, Louisiana, South Carolina, and Texas. He says that it is extirpated in South Carolina.

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:High significance
Comments: Waterbodies in freshwater drainages of Texas and Louisiana, Alabama, Georgia, Florida, Mississippi, Arizona, California, and Hawaii (Jacono, no date).

8. Proportion of Nation's Biogeographic Units Invaded:Low significance
Comments: Established in approximately 11 TNC ecoregions (Inference using data from Kartesz 1999 and TNC Ecoregion 2001 map).

9. Diversity of Habitats or Ecological Systems Invaded in Nation:Insignificant
Comments: Invades freshwater wetlands, ponds, and streams (Weber 2003). Poses a serious threat to lakes, ponds, streams, rivers and other freshwater wetlands, and cultivated rice fields (Swearingen et al. 2002). Inhabits still waters of man-made and natural lakes and ponds, oxbow lakes, ditches, stream margins, and wetlands. Expected to occupy habitats favorable to S. minima, yet predicted to extend into and colonize open water more aggressively. (Jackman 2003) Invades still or slowly moving fresh to slightly brackish waters in tropical, subtropica, and warm temperate regions (PIER 2003). Represents a significant danger to warm, slow-moving bodies of water (Rice 2002).

Subrank III. Trend in Distribution and Abundance: High

10. Current Trend in Total Range within Nation:High significance
Comments: Spreading at an alarming rate. Since 1997, this plant has been found in North Carolina, Hawaii, Alabama, Texas, Mississippi, South Carolina, Louisiana, and Florida (USACE, no date).

11. Proportion of Potential Range Currently Occupied:High significance
Comments: Expected US range includes the Atlantic coastal plain, from southeastern Virginia to southern Florida, the Gulf coast states, central and southern California, and southern Arizona. Expected to naturalize wherever water-hyacinth persists and in areas that experience frost but not in the formation of ice on freshwaters (Jacono, no date). Represents a significant danger to warm, slow-moving bodies of water (Rice 2002).

12. Long-distance Dispersal Potential within Nation:High significance
Comments: Spread into new water bodies by boats and fishing gear, and dumping of aquaria. Fragments are transported by water, humans, and wildlife. (Swearingen et al. 2002)

13. Local Range Expansion or Change in Abundance:High/Moderate significance
Comments: Can double its numbers every 2.2 days under ideal conditions (USACE, no date).

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Moderate significance
Comments: No major disturbance required to establish in slow-moving freshwater bodies, however these habitats usually have some ongoing minor natural disturbances.

15. Similar Habitats Invaded Elsewhere:High/Low significance
Comments: Invades Australia, New Zealand, tropical Asia, and tropical and southern Africa (Weber 2003). A serious weed in New Guinea, Australia, Mauritius, Africa, India, Sri Lanka, Ceylon, New Zealand, and elsewhere (Rice 2002).

16. Reproductive Characteristics:High significance
Comments: Spreads solely by vegetative growth and fragmentation, fast growing in nutrient rich waters, (Weber 2003). Not known to reproduce by spores (Jackman 2003). Can double its numbers in as little as 2-10 days, extremely small fragments are effective, viable propagules (Rice 2002). This plant fragments spontaneously as plants mature, new branches develop from apical and lateral buds and each node harbors up to five serial lateral buds. It does not reproduce by spores because it is a pentaploid species, and only creates sporangial sacs that are usually empty of microscopic spores or with only a few deformed remnants. It will withstand periods of stress, both low temperature and dewatering, through latent buds. Plant populations have been found to double in size every 2-4 days. A single plant has been described to cover fourty square miles in three months. (Jacono 2003)

Subrank IV. General Management Difficulty: Unknown

17. General Management Difficulty:Moderate significance
Comments: Large infestations can be mechanically harvested, but this method promotes fragmentation and spread of this plant (Weber 2003). Biological control using the weevil, Cyrtobagous salviniae, is the most effective way of removing salvinia. However, it requires high water temperatures in order to survive. (PIER 2003) Chemical treatment is also effective (Rice 2002).

18. Minimum Time Commitment:Not ranked

19. Impacts of Management on Native Species:Not ranked

20. Accessibility of Invaded Areas:Not ranked
Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 08Mar1991
NatureServe Conservation Status Factors Author: Broaddus, Lynn

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Jackman, J.A. 2003, last updated October 6. Biological control of weeds in Texas. Texas A&M University, Department of Entomology, College Station, TX. Available: http://bc4weeds.tamu.edu/index.html. (Accessed 2004).

  • Jacono, C.C. 2003. Identification of Salvinia molesta D.S. Mitchell. USGS. Available: http://salvinia.er.usgs.gov/html/identification.html. (Accessed 2004).

  • Jacono, C.C. No date. The biology of Salvinia sp. National Agricultural Pest Information System. Available: http://www.ceris.purdue.edu/napis/pests/gs/facts/bio.html. (Accessed 2004).

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • Pacific Island Ecosystems at Risk Project (PIER). 2003. Plant threats to Pacific ecosystems - species of environmental concern. Last updated 20 December 2003. Online. Available: http://www.hear.org/pier/threats.htm. (Accessed 2004).

  • Rice, B. 2002. Weed alert: Salvinia molesta. The Nature Conservancy. Available online at: http://tncweeds.ucdavis.edu/alert/alrtsalv.html. (Accessed 2004).

  • Swearingen, J., K. Reshetiloff, B. Slattery, and S. Zwicker. 2002. Plant Invaders of Mid-Atlantic Natural Areas. National Park Service and U.S. Fish & Wildlife Service, 82 pp.

  • The Nature Conservancy. 2001. Map: TNC Ecoregions of the United States. Modification of Bailey Ecoregions. Online . Accessed May 2003.

  • Thomas, P.A. and P.M. Room. 1986. Taxonomy and control of Salvinia molesta. Nature. 320(17):581-584.

  • U.S. Army Corps of Engineers, Aquatic Plant Control Section. No date. Salvinia molesta - possibly the world's worst weed. Jacksonville District, Florida. Available: http://www.saj.usace.army.mil/conops/apc/salvinia.pdf. (Accessed 2004).

  • Weber, E. 2003. Invasive plant species of the world: a reference guide to environmental weeds. CABI Publishing, Cambridge, Massachusetts. 548 pp.

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