 |
|
|
||||
| NAS - Nonindigenous Aquatic Species |
Translate this page with 
Common Name: giant salvinia
Synonyms and Other Names: Kariba weed, African pyle, aquarium watermoss, koi kandy
Taxonomy: available through 
Identification: Floating, rootless aquatic fern. Consists of horizontal stems that float just below the water surface, and produce at each node, a pair of floating or emergent leaves. Floating and emergent leaves are green in color and ovate to oblong in shape. Plants bear a third leaf that is brown, highly divided and dangles underwater. Submersed leaves are commonly mistaken as roots. They may grow to great lengths, and by creating drag, act to stabilize the plant.
Upper surfaces of green leaves are covered with rows of white, bristly hairs. The stalks of each divide into four thin branches that soon rejoin at the tips to form a cage. The resulting structures resemble tiny eggbeaters. Cage-like hairs may be damaged on mature leaves, thereby not appearing true to this description. Young, unfolding leaves will, however, reveal intact structures. These specialized hairs create a water repellent, protective covering.
Salvinia molesta belongs to a group of closely related Neotropical species that share the feature of eggbeater type hairs. Named the “Salvinia auriculata complex”, the members include S. auriculata Aublet, S. biloba Raddi, S. herzogii de la Sota, and S. molesta. Although subtle differences have been found among the members of the group, sporocarps are generally needed to tell these species apart.
Sporocarps develop in elongated chains among the submersed leaves. Salvinia molesta is known for it’s of egg-shaped sporocarps that end in a slender point. Mature plants can produce large quantities of sporocarps, which are actually outer sacs that contain numerous sporangia. However, the sporangial sacs are usually empty of microscopic spores or with only a few deformed remnants. Being a pentaploid species, S. molesta demonstrates irregularities during meiosis that prevent spore formation and result in functionally sterile plants (Loyal and Grewal 1966).
Three growth forms have been described where individual leaves can range from a few millimeters to 4 centimeters in length. During early colonization small leafed, thin plants lie flat on the water surface. As populations expand, leaves curl at the edges in response to self-competition. Later a vertical leaf position is attained as mature plants press into tight chains to form mats of innumerable floating plants (Mitchell and Thomas 1972; Mitchell and Tur 1975).
Native Range:
South America
Nonindigenous Occurrences: Salvinia molesta (giant salvinia) has been recorded, since 1995, from over 150 locations in 69 freshwater drainage basins of Alabama, Arizona, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, North Carolina, Puerto Rico, South Carolina, Texas, and Virginia.
Distribution summaries, highlights, and updates follow:
South Carolina: In 1995, the first occurrence of Salvinia molesta growing outside cultivation was recorded in the Broad-St. Helena Drainage (Johnson 1995). The 1.5 acre infestation at a private pond, originating from a contaminated shipment of water garden plants from California, was chemically treated the same year it was found and is considered eradicated (SC AISMP 2008). In 2004, approximately two acres of giant salvinia were found infesting two private plantation ponds and their associated canals in Jasper County. Plants escaped from a nearby ornamental water garden after being purchased from a Savannah nursery. This is the second record of Salvinia molesta in the state and the second occurrence in the Broad-St. Helena drainage. This population was successfully eradicated by 2006 using repeated herbicide treatments (SC AISMP 2008).Texas: Salvinia molesta first collected in May of 1998 at a schoolyard demonstration pond in Houston [Ronald Jones s.n. (TAES)]. That same year it was also confirmed in Toledo Bend Reservoir (J. Hyde, pers. comm.); the Lower Sabine River (just downstream of the Toledo Bend dam) (C. D'Arbonne, pers. comm.); canals serving an energy plant near Bridge City, Coon Bayou, Swinney Lake and numerous private ponds near Tomball, Garawood, Hemphill, the Brazos River, and Sandy Creek. (K. McDowell, pers. comm.)
During 1999, S. molesta was recorded in an old fish hatchery pond at Sheldon Lake State Park, impounded creeks and private stock ponds near Flower Mound (C. Owens, pers. comm.) and near Houston, Lovelady, Franklin, Friendswood, Alvin and Mont Belvieu. In Mont Belvieu twin reservoirs with approximately 50 infested acres flooded into nearby rice irrigation canals, which themselves drain into Cedar Bayou (R. Helton, pers. comm.). By late August, S. molesta was discovered at Lake Texana, a 11,000 acre impoundment of the Navidad River (L. Hartmann, pers. comm.). The source was traced to a private pond two miles upstream, that had flooded into Sandy Creek, a tributary of the reservoir.
In 2000, infestations were confirmed in Lake Conroe (a 21,000 acre impoundment on the West Fork San Jacinto River), the Sheldon Reservoir and Champion Lake. By 2001, a new occurrence at a private pond in Splendora filled the distribution gap in the salvinia hotspot of southeast Texas. A now contiguous block comprises eleven separate drainage units hosting S. molesta populations. Later this year, four public reservoirs, six rivers or streams and twenty-five ponds were confirmed with S. molesta in Texas. Populations on Toledo Bend and other public reservoirs were significantly smaller, but still required herbicide treatment.
Between 2002 and 2005, S. molesta infestations had dispersed to Smithers Lake, a SE Jackson County reservoir, a man-made pond at a Leauge City school, plus another eleven ponds on private property. Of these, Smithers Lake, which serves as a cooling reservoir for a local power plant, and a private six-acre pond near Center, Texas, were targeted for herbicide treatments (H. Elder, pers. comm.) (R. Jones, pers. comm.).
In 2006, Texas Parks and Wildlife confirmed new infestations at Lake Center, where S. molesta had probably been present for one to two years, at the Pinkston Reservoir where a small population was found, treated, and possibly eradicated, and at Caddo Lake in September (H. Elder, pers. comm.). Caddo Lake at nearly 27,000 acres is the largest natural lake of fresh water in the south, straddling the Texas-Louisiana border and is a Ramsar Wetland of International Importance.
An infestation at B.A. Steinhagen Lake, in the Lower Neches drainage, was found in 2007. Most recently in 2008, two localized infestations have been found: one near Coleman Creek area on Sam Rayburn Reservoir and another in the Kickapoo arm of Lake Palestine (H. Elder and R. Ott, pers. comm.). Containment and treatment plans are underway in both sites and full surveys of the water bodies will be conducted.
Louisiana: The first introduction into Louisiana was just a handful of plants collected in 1998 at Bayou Teche in Breaux Bridge; they are suspected to have been carried in on a boat trailer launched at the Breaux Bridge ramp [M. Griffis (NWRC) # 2830]. Although the plants were mature, bearing sporocarps and of the mat-forming stage, surveys and repeated visits failed to locate more Salvinia molesta in Bayou Teche; thus, the species is not considered as established there (C. Dugas, pers. comm.). Also found in September 1998 on the Louisiana side of Toledo Bend Reservoir, a 186,000 acre impoundment of the Sabine River on the Texas-Louisiana border.
Between 1999 and 2005, S. molesta was found in canals adjacent to a small diked swamp near Houma (Terrebonne Parish.), near the Cameron Canal and adjacent marsh ponds (Cameron Parish) and in private ponds near Duson (Lafayette Parish.). Despite continued herbicide efforts the Houma infestation spread by Dec. 2001 to drainage ditches and a crawfish pond on the neighboring wet pasture (C. Dugas, pers. comm.). Winter storms in 2003 caused extremely high flood conditions that washed S. molesta out of the Cameron Canal and into an extensive marsh system that could easily affect hundreds of acres. Giant salvinia was confirmed in the Jefferson Davis Parish in late 2004 after an alert landowner reported it in his farm ponds in Fenton. In 2005, a canal south of Lake Salvador in Lafourche Parish was found infested.
Since 2006, giant salvinia has spread to over eight new waterbodies, including Caddo Lake (Jeem’s Bayou), Cross Lake, and Black Bayou at Hosston in Caddo Parish; Lake Bistineau in Webster, Bienville and Bossier Parishes; Grand Bayou Reservoir in Red River Parish; Smithport-Clear Lake in DeSoto Parish; Wallace Lake in DeSoto and Caddo Parishes; and Red River Pool 5 in Bossier and Caddo Parishes. It’s also spread to the Atchafalaya Basin in St. Martin, Iberia and St. Mary Parishes and in the Intracoastal Canal in Terrebonne Parish in south Louisiana (C. Dugas, pers. comm.).
Florida: First positively identified occurrence in the state was in February 1999 a Naples canal following months of chemically treating a population believed to be Salvinia minima [Jacqueline Smith s.n. (FLAS)]. Salvinia molesta is suspected to have been occurring in the Airport Rd. canal for approximately three years. In September 2000, heavily infested retention and irrigation ponds draining the canal were discovered to be the source of reoccurring plants (J. Smith, pers. comm.).
In 2000, a few plants were found in a a 5 acre subdivision pond, also in Naples, just days after being placed there by a resident. No plants were observed in Naples during 2001, following chemical control measures at each site, but in early 2002 and 2003, heavy growth of S. molesta reappeared at the Airport Rd. canal in Naples. Plants were found several miles north of previous occurrences but below the junction with the Immokalee Rd. canal (M. Brodie and V. Vandiver, pers. comm.). Plants the size of a silver dollar grew snagged in alligatorweed (Alternanthera philoxeroides) ¼ mile north of previous occurrences (V. Vandiver, pers. comm.). During this time frame, plants were also found in nurseries or retention ponds near nurseries in Collier, Dade and Volusia counties.
In 2004, Salvinia molesta was discovered in the Golden Gate Canal, Naples (M. Brodie, pers. comm.). This new location is separate from, but just a few miles south of the Airport Road canal, a site where plants have both flourished and diminished for at least five years. Also found in Fort Lauderdale (Broward County) and near a residential subdivision of Gainsville (Alachua Co.). Most recent infestations have been in Blue Lake near Oklawaha (2006) and in Lake Laurie, NW of Quincy (2007); both of these have been subject to chemical and/or biological control (R. Kipker and J. Van Dyke, pers. comm).
Alabama: Identified in March of 1999 in a seven acre golf course pond in Auburn in March of 1999 [William Bryant s.n. (UNA)], but is suspected to have been there since 1997 (M. Masser, pers. comm.). Flooding in July 1999 dispersed plants from this golf course to two impounded tributaries of Sougahatchee Creek. Also recorded this same year in a private 3.8 acre pond north of Seale in August and in December just upslope in a neighboring pond,probably transported by animals such as raccoons or turtles (J. Zolcynski, pers. comm.).
In 2000, the plants found the previous year were treated with systemic herbicides and thought eradicated. In October, 2000 an infestation in a pond near Montgomery was found and chemically treated the following day (J. Jernigan, pers. comm.). In February2001 S. molesta confirmed at an Auburn University pond, again in the Sougahatchee drainage, where plants survived the coldest winter in eight years (W. Moore Jr., pers. comm.). As of November 2002, the plants at previously reported, chemically treated ponds in the eastern portion of the state have not returned. However, giant salvinia remains following herbicide treatment and scouring rains at the Auburn University pond (J. Jernigan, pers. comm.).
Hawaii:1999 April A rapidly expanding infestation of Salvinia molesta at Enchanted Lake , Kailua, on the island of Oahu (Robert Bourke, Oceanit Laboratories), was feared to threaten the nesting habitat of three endangered water birds, the Hawaiian coot (Fulica alai), the Hawaiian gallinule (Gallinula chloropus sandvicensis) and the Hawaiian stilt (Himantopus mexicanus knudseni). Repeated volunteer efforts to mechanically remove Salvinia molesta from Enchanted Lake appear to have abated the infestation in the freshwater portion of this oligohaline lagoon. By December 2000 the population was substantially reduced.
April Small (<1 acre) infestations also found in 1999 at taro patches and at Lake Wilson, Oahu (Fred Kraus, pers. comm.).
2001
March New occurrences of Salvinia molesta found at streams on Oahu Island. Inaole Stream at Bellow's Airforce Base hosts a population 30 ft. wide and 500 ft. long (M. Anderson, pers. comm.).
August Left untreated, giant salvinia at Lake Wilson, a public reservoir in Wahiawa, has increased substantially to form dense mats extending several meters off the shoreline and rafts in open water.
2003
February A small patch of Salvinia molesta was discovered a few years ago in Lake Wilson and today it completely covers the 300-acre lake. A city-state-federal task force decided this month to try to remove the noxious weed using an amphibious excavator, but so far little progress has been made. Now, the State Department of Agriculture has decided to aid the excavation efforts by applying the herbicide Rodeotm. The herbicide application has begun as officials look for new areas on the lake to continue their excavation efforts. (courtesy of Michael Smart, pers. comm. and photos courtesy Army Corps of Engineers)
May Salvinia molesta continues to cause problems for Hawaii. It has been found in two new locations on the Oahu Island, where Oahu populations are apparently spreading. New localities exist at Kawainui Marsh in Kailua and around a flood control dam at Ho'omaluhia Botanical Garden in Kaneohe. More importantly, giant salvinia has recently been introduced to the big island of Hawaii island where it now occurs at Waiakea Pond in Hilo (M. Wilkinson, pers. comm.).
Mississippi: 1999
April Giant salvinia recorded near Moselle [Milton Henderson s.n. (IBE)] at a 1/4 acre spring fed pond and escaped in the ditch below the pond. The water surface had been covered since 1998, a population developing from four plants released by the owner (P. Butler, pers. comm.). The pond has received extensive herbicide treatment.
2003
July MDWFP Fisheries Biologist Tom Holman finds no sign of Salvinia molesta after repeat annual surveys of the pond near Moselle. The site was chemically treated in 1999 and the population is believed to have been eradicated (D. Riecke, pers. comm.).
2004
August Salvinia molesta discovered in Petal, MS, where mature plants are abundant in a 40 + acre marshy bottomland lake system. The area is precariously close to the lower Leaf River and its associated oxbow lakes. Lake system, early 2004 Lake system, summer 2004
California/Arizona: 1999 August Salvinia molesta was first observed on the Lower Colorado River at Imperial National Wildlife Refuge, bordering Arizona and California. Thousands of free floating plants were estimated in the river, an occurrence suspected as resulting from water release from a nearby canal (A. Velasco, USFWS memos, 6 & 16 Aug. 1999). A multi-agency survey of the Colorado River and associated backwaters and canals (ranging from Parker Dam to Imperial Dam) delineated the infestation as originating on the California side of the Colorado River, in the Palo Verde Irrigation District Drain (PVID). The PVID system flows into the Old Colorado River channel before entering the Colorado River. The survey found giant salvinia in the Colorado River from the PVID outflow downstream to Imperial Dam (C. Minckley, pers. comm.; Map: Salvinia molesta Survey Results, Bureau of Reclamation, Aug. 1999).
September Public information campaigns proved successful when a resident reports Salvinia molesta from the San Diego River. An 8 ft. diameter patch of giant salvinia was found in a ponded portion of the San Diego River, San Diego County. This infestation was outside of the flow of the seasonal river and was eliminated with herbicides before contaminating the main stream (R. O'Connell, pers. comm.).
2001
November Repetitive herbicide application (as much as 16 times per year) in the Palo Verde Irrigation District Drain in hand with the removal of salt cedar (Tamarix sp.) harboring Salvinia molesta in underbrush, has resulted in markedly decreased numbers of plants along regions of the California drain.
Federal refuges on the Colorado River below the drain have halted herbicide spraying this year. Mats and floating plants continue to persist there.
2003
February Salvinia molesta is continuing its southward spread in the Lower Colorado River. A local citizen and her son found plants this month along the muddy shoreline of the Colorado River near Yuma, AZ. The plants were scattered and occassional; however, they were especially large, fully mature and bore sporocarps.
Georgia: August 1999 Edie Creek, a tributary of the Upper Ocmulgee River, holds infestation first noticed at a small farm impoundment.
December Plants had spread downstream to a larger open-ended impoundment along the creek (F. Ellis, pers. comm.). Salvinia molesta found at subdivision ponds north east of Atlanta, also in the Upper Ocmulgee drainage. Below the ponds, a single plant was found in an unnamed tributary of the Yellow River (B. Mauldin, pers. comm.).
2001
November Salvinia molesta not found to persist in Georgia. Although some sites had received herbicide treatment in December 1999, cold winter temperatures are believed to be the real force in this apparent elimination (S. Robinson, pers. comm.).
2003
July Salvinia molesta discovered in the Lower Ogeechee drainage of eastern Georgia in a private pond in Bryan County. The small, spring fed pond was densely covered with a thick layer of plants. GA Department of Natural Resources has already begun to treat the infestation with herbicides. A few plants were also observed below the dam but none were found in a survey of the stream below the infested pond [R. Martin and T. Hendrickx, pers. comm.; Ramon Martin s.n. (FLAS, GA)].
2004
June Salvinia molesta discovered new to the Canoochee drainage, at a 9-acre private pond near Claxton. Georgia DNR believes the giant salvinia was unintentionally introduced with water hyacinth, Eichhornia crassipes, purchased from a Savannah store. The pond is now infested with an abundance of mature plants [T. Will and R. Martin, pers. comm.; T. Will s.n. (FLAS, GA)].
2005
March Giant salvinia, associated with water hyacinth, was found blanketing the surface of a 0.6 acre pond in Macon, Georgia. Georgia DNR found no plants downstream in a recent survey; however they are concerned because the pond drains into Lake Tobesofkee, a 1750 acre recreational reservoir (M. Gray, pers. comm.).
North Carolina: September 2000 Salvinia molesta discovered at independent sites in three drainage basins of southeastern North Carolina. Infestations reported by Stratford Kay:
1. Northeast of Burgaw, in a swamp slough located 100 yards (30m) from the Northeast Cape Fear River. Flooding from hurricanes in 1999 left plants stranded in trees 12 ft. (3.6m) above ground at this site.
2. Jacksonville, scattered in bottomland woods near a creek draining the New River, after heavy rain washed plants from a resident's pond.
3. Wilmington, blanketing golf course ponds on the Cape Fear peninsula.
2001
October Populations over wintering and surviving well (D. Patterson, pers. comm.).
2002
May Preparation of voucher specimens by S. Kay documented Salvinia molesta persisting at all three sites in North Carolina (Kay s.n. NCSC; FLAS).
July New site, a private pond in Hubert, Onslow Co., was confirmed and chemically treated.
August Late summer finds Salvinia molesta suddenly spreading well beyond the original slough site and deeper into the swamp near Burgaw, on the Northeast Cape Fear River drainage, Pender Co. (D. Horkavy and S. Kay, pers. comm.).
2003
July A new population of Salvinia molesta was found in a marshy area just 2 miles south of the golf course on the Cape Fear peninsula where plants have been persisting since 2000. North Carolina has decided to tackle all their populations of S. molesta with extensive herbicide treatments. Progress is being made, but NC officials know that this is not going to be an easy task (W. Batten, pers. comm.).
2004
July Salvinia molesta makes its sixth appearance in North Carolina, this time in Sampson County. This discovery marks a new drainage in North Carolina lying adjacent to previous drainages with Salvinia molesta infestations. Plants were found in a small, private pond near Delway where the landowners had placed them after purchasing them from a local garden center a few years back. Giant salvinia now covers almost 25% of the pond and North Carolina officials are working on its eradication (W. Batten, pers. comm.).
Virginia: Salvinia molesta is first found August 2004 at a private pond in Shenandoah County, near the town of Strasburg. The small, (0.3 acre) spring fed pond is blanketed with Myriophyllum aquaticum (parrot feather) and giant salvinia. Surrounding streams were surveyed for plants that may have escaped the pond, but no plants were found. VA DCR and local volunteers will try to manually remove the plants before resorting to chemical treatment (C. Hutto, pers. comm.).
Ecology: Reproduction: Salvinia molesta effectively reproduces through vegetative means. Stems fragment spontaneously as plants mature. New branches develop from apical and lateral buds. Each node harbors up to five serial lateral buds (Lemon and Posluszny 1997), adding to the high potential for growth and dormancy. Salvinia molesta will withstand periods of stress, both low temperature and dewatering, through latent buds.
Habitat: Quiet water of lakes and ponds, oxbows, ditches; slow flowing streams and rivers, backwater swamps, marshes and rice fields.
Means of Introduction: Human transport will spread giant salvinia locally. Copious hairs on leaf surfaces and deeply embedded lateral buds are two features that provide protection against desiccation. Plants easily adhere to and can be carried overland on anything entering infested waters. Boats, trailers, vehicular wheels, engine intakes, fishing and recreational gear, even boots can host and carry hitchhiking plants. Trails of plants are common along boat ramps and roads leading from Toledo Bend Reservoir. Toledo Bend is a famous fishing spot within a days drive from many favorite fishing lakes. Lakes Sam Rayburn, Steinhagen and Livingston are at considerable risk as they host thousands of boats that are commonly trailered back and forth. These large Texas reservoirs have thousands of acres of quite backwaters and drain into sensitive natural areas downstream (R. Jones pers. comm.).
Spread will continue through natural drainage and flow in river and stream systems. In lakes and large water-bodies upright well buoyed leaves are effectively dispersed by wind and currents to infest new coves.
Status:
Impact of Introduction:
Remarks:
References
Other Resources:
Description
Time Series Map
United States Distribution
Cultivated U.S. Distribution
Predicted U.S. Range
Alert Flyer (Adobe Acrobat PDF)
Line Drawings
Visual guide for distinguishing three salvinia species: Salvinia molesta, Salvinia minima and Salvinia oblongifolia
Author: V. Howard
Revision Date: 2/12/2008 Citation for this information:
V. Howard. 2009. Salvinia molesta. USGS Nonindigenous Aquatic Species Database, Gainesville, FL.
<http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=298> Revision Date: 2/12/2008
| AccessibilityFOIAPrivacyPolicies and Notices | |
  |
|