Description

Phragmites australis is a complex species, varying greatly over its worldwide range, and locally, in chromosome number, in individual alleles, and in morphology (Gervais et al. 1993; Haslam 1972; Hauber et al. 1991; Tucker 1990; Ward et al. 2010; Guo et al. 2013). As a species, P. australis is native to North America, but rapidly expanding, invasive populations in the eastern United States have long been suspected as possible introduced genotypes. Analysis of chloroplast DNA sequences of living plants has confirmed this suspicion. According to this analysis, at least 11 haplotypes of P. australis are native to North America (Saltonstall 2002a), and at least 5 are native to Northeastern North America (Saltonstall 2002b). Native North Amewrican forms are now recognized as P. australis spp. americanus (Saltonstall et al. 2004). tHowever, Haplotype M, the dominant type in Eurasia and North Africa, appears to have been introduced to North America in the 19th century, and now dominates populations of P. australis from Nova Scotia to South Carolina (Saltonstall 2002a). In recent samples from the Atlantic Coast between ME and SC, native haplotypes (F and Z) were found at many scattered locations (Saltonstall et al. 2002; Meadows and Saltonstall 2007). Eleven Chesapeake Bay samples, from locations ranging from the upper Bay to the mouth and adjacent Atlantic, were haplotype M (Saltonstall 2002b). This introduced haplotype is now the predominant form of P. australis in the Chesapeake Bay region. Preliminary observations indicate that native and introduced haplotypes can be distinguished visually. However, these distinctions have not yet been developed for all the North American haplotypes (Blossey 2002).

Additonal introduced forms of P. australis have been found in North America. Meyerson et al. (2013) identified stands of Haplotype L, from northern Europe, in Quebec, and populations on the Gulf Coast have recognized as Haplotype I, or 'Med', introduced from the Mediterranean and Africa (Saltonstall et al. 2002; Lambertinit et al. 2006; Guo et al. 2013).

Species Names - The first valid species description was from Australia- the name Phragmites australis took precedence over the widely used name Phragmites communis. Some of the many genetic forms of P, australis show the characterisitcs of separate species, including differences in chromosome numbers, and low rates or an absence of hybridization (Saltonstall et al. 2004; Meyerson et al. 2010; Ward 2010;). It is likely that many of these forms will be given full species status in the future.

Potentially Misidentified Species - Arundo donax (Giant Reed) is introduced and local in uplands and nontidal wetlands, Saccharum giganteum (=Erianthus giganteus, Giant Plumegrass, Sugarcane Plumegrass) is native, in nontidal wetlands and uplands.

Taxonomy

Kingdom	Phylum	Class	Order	Family	Genus
Plantae	Magnoliophyta	Liliopsida	Cyperales	Poaceae	Phragmites

Synonyms

Phragmites communis; Phragmites vulgaris; Phragmites phragmites; Phragmites berlanderi; Arundo phragmites; Arundo panicula laxa

Invasion History

Chesapeake Bay Status

First Record	Population	Range	Introduction	Residency	Source Region	Native Region	Vectors
1881	Established	Expanding	Introduced	Regular Resident	Europe	Eurasia	Shipping(Dry Ballast), Agriculture(Agricultural Weed; Packing Material), Natural Dispersal(Natural Dispersal)

History of Spread

Phragmites australis (Common Reed, Phragmites), appears to have native populations on every continent except Antarctica (Haslam 1972). It has probably been so affected by human transport and habitat disturbance that its original range is unknown (Holm et al. 1977; Cook 1985). As a species, it is native to North America, and has been found in 3,000 year-old peat in CT, and 1,400-1,100 year old woven artifacts in CO (Marks et al. 1994). Phragmites australis is listed here because of its apparently recent appearance (1910-1950) in many parts of the Chesapeake Bay and surrounding region, and a widespread suspicion that a dramatic increase in its abundance and invasiveness on the Atlantic Coast is due to introduction of a new genotype to eastern North America (Marks et al. 1993; Metzler and Rozas 1987; Tucker 1990; Chambers et al. 1999). Recent genetic research has confirmed this suspicion (Saltonstall 2002a).

At least 11 chloroplast DNA haplotypes of P. australis are native and unique to North America. They are now recognized as P. ausralis ssp. americanus (Saltonstall et al. 2004). The form prevailing on the Gulf Coast and Atlantic coast of FL, haplotype I or Med, is shared with South America, southern Europe, Asia, and Africa, but its introduction status is uncertain (Saltonstall 2002a; Lambertini et al. 2006; Guo et al. 2013). At least 5 haplotypes are native to northeastern North America (Saltonstall 2002b), but the invasive form now predominating in this region, haplotype M, appears to be native to Eurasia, and introduced to North America in the 19th century (Saltonstall 2002a). Dry ballast or garden varieties are possible sources for supposed exotic invasive genotypes (Marks et al. 1993). Several cultivated ornamental varieties have been introduced (Metzler and Rozas 1987).

The first collections of P. australis in North America are from the Chesapeake region. An herbarium specimen of this plant from MD, collected by William Krieg before 1698, is in the British Museum (Mountford 1997), although P. australis is not listed among MD specimens collected by Krieg and others in British herbaria by Brown et al. (1987). John Clayton (Clerk of the Court for Gloucester County) collected this plant in VA in the 1730's, [as 'Arundo panicula laxa' in Gronovius' 'Flora Virginica' (Gronovius 1739; Reveal 1983)]. Pursh also found it in southeast VA when he collected there, while headquartered at a plantation in Southampton County (located inland, south of the James River) in 1806 (Pursh 1814; Harvill et al. 1992). However, there are no further reports of this plant from the Chesapeake Bay region until the early 20th century (Kearney 1901; Shreve et al. 1910; Hitchcock and Standley 1919).

The genetic identity of the early (1697-1806) specimens is not known. Two native genotypes have been found in recent collections in Chesapeake Bay, in Allens Fresh MD (along the Wicomico River, a Potomac River tributary), and along the Rappahannock River in VA (Saltonstall 2002b). Records ofP. australis in a 1901 survey of the Norfolk-Virginia Beach area ( Kearney (1901), could represent a native population:' Phragmites communis is not uncommon near the heads of bayous, but rarely makes a dense stand to the exclusion of other species' (Kearney 1901). Most of the early records of P. australis probably represent P. australis ssp. americanus
(Saltonstall 2004).

19th century floras suggest that the distribution of P. australis was centered along the northeastern coast in the early 19th century, with a range expansion southward. Some examples are listed below:

Canada-ME-VA (1814-1848)- Pursh (1814) lists P. australis as 'On the banks of rivers and in large salt-marshes, Canada to Virginia, common. Gray described its distribution as 'Edges of ponds and swamps, common northwards' (Gray 1848). Saltonstall did not examine specimens from this period, but the early populations are presumed to have consisted largely or wholly of native genotypes. In recent (1997-2001) collections from the northeast Atlantic Coast and Great Lakes regions, native haplotypes were found in Nova Scotia, New Brunswick, Ontario, and 2 Chesapeake Bay locations. Altogether 14 specimens represented native haplotypes, versus 105 for the introduced haplotype M (Saltonstall 2002b).

Boston MA and vicinity- Phragmites australis 'resembles a field of standing corn' (Bigelow 1814). Native haplotypes were collected as late as 1926 on Martha's Vineyard. The introduced haplotype M was collected in 1915 in South Boston. Haplotype M is the only form found in recent collections near Boston and on Cape Cod (Saltonstall 2002b).

CT- The latest specimen of a native haplotype was collected in 1935, on Fishers Island NY, off the CT coast in Long Island Sound. Specimens of haplotype M were collected in Madison and New Haven CT in 1875 and 1885 respectively. Haplotype M is the only form found in recent collections (33 samples) in CT (Saltonstall 2002b).

New York City area- Phragmites australis was 'common in the Newark meadows...also in Pennsylvania and Delaware' (Torrey 1823). Haplotype M was the only form found in 5 collections from Long Island and northern NJ (Saltonstall 2002b).

Philadelphia, and adjacent NJ-DE-- Phragmites australis was not mentioned in Barton (1818), but was listed as rare by Darlington (1853). Near Wilmington DE, P. australis was found on 'Muddy shores of Christiana Creek, near the lighthouse' (Tatnall 1860). Phragmites australis was abundant on dry ballast piles at Philadelphia. The form present there thought to be a distinct and unusual variety (Martindale 1875; Burk 1878). A specimen of haplotype M was collected from ballast grounds at Camden NJ in 1877 (Saltonstall 2002b).

Baltimore MD and Washington DC - Phragmites australis was apparently absent in the 1800's, and was first recorded by Shreve et al. (1910) near Baltimore, and by Hitchcock and Stanley (1919) for DC. However, Herbarium specimens were collected within 40 km of the two cities in 1883-1902 (US National Herbarium collections). One of these early specimens, from 1905, was identified as haplotype M (Saltonstall 2002b). (Details of the Chesapeake invasion are given below).

NC-SC-GA - Phragmites australis was not mentioned by Walter (1788) , Elliott (1824) or Curtis (1867). Hitchcock's (1935) range map shows no records in the southeastern states from VA to GA. The first record from the Carolinas or GA was in 1973 by Stalter (1975) for SC. By 1991, this species had become a dominant species in portions of brackish marshes on the SC coast (Stalter and Baden 1994). Recent specimens from NC and SC were haplotype M (Saltonstall 2002b).

FL and Gulf States - Phragmites australis was present in southern LA (Langlois 1887) and Chapman (1860) gives the habitat and range as 'deep river marshes near the coast, Florida and northward.' Four herbarium (1905-1910) and 9 recent specimens examined by Saltonstall from FL, AL, LA, and TX were the cryptogenic haplotype I. Three specimens from Plaquemines Parish LA, on the Mississippi River, were the introduced haplotype M (Saltonstall 2002b).

Populations of the invasive haplotype M now appear to be scattered across North America, with some occurring on the Pacfic coast. However, occurrences are most frequent in the northeast and Great Lakes regions (Saltonstall 2002a).

Chesapeake Bay records after 1814 are summarized below:

Phragmites australis was found in a survey of the Norfolk-Virginia Beach area by Kearney (1901), not too far from Clayton and Pursh's collecting area. 'Phragmites communis is not uncommon near the heads of bayous, but rarely makes a dense stand to the exclusion of other species' (Kearney 1901).

Phragmites australis was not listed for Baltimore by Aikin (1837), Sollers (1888), or the District of Columbia by Brereton (1831), Potomac Side Naturalists Club (1876), Ward (1881), or additions to Ward's flora (1885-1901). However, herbarium specimens were collected in Anne Arundel County MD in 1883, and in adjacent Chesapeake Beach (Calvert County) in 1905, 1912 and 1919. This reed was also collected along the Bush River (Harford County) in 1902 (US National Herbarium collections). The 1905 Chesapeake Beach specimen was sampled by Saltonstall and identified as haplotype M (Saltonstall 2002b).

The first published report of Phragmites australis from MD was by Shreve et al. (1910), with two specific locations mentioned, (Patapsco River above, and the Nanticoke River, Vienna, Wicomico County, MD) and treated overall as 'frequent' in marshes. The first report from the District of Columbia was by Hitchcock and Standley (1919), along Potomac ('near the steel plant'). Phragmites australis may have been somewhat local in the early 20th century. It was absent from two local floras, one for the vicinity of Williamsburg VA (Erlanson 1924) and another for Worcester Co. MD (Redmond 1932). However, it was reported from another outlying location; Pocomoke Swamp, MD-VA (Beaven and Oosting 1939), and was considered 'Common... as far south as Sussex (DE) and Dorchester (MD) Counties' by Tatnall (1946).

Phragmites australis was reported in 9 of 17 local studies of Chesapeake marsh and shore vegetation conducted from 1966-1994. Interviews with local botanists (Silberhorne 1995, Sipple 1995; Humaira Khan 1996 ) indicate that the abundance of P. australis around Chesapeake Bay has increased drastically in the last 20-30 years. Studies of 6 Chesapeake Bay marshes (4 on the Patuxent River, 2 on the Eastern Shore) using aerial photography and GIS indicated that the area of P. australis colonies increased by 0.4-12.2% per year, with fastest spread in oligohaline marshes, and in the most recently formed colonies (Rice and Stevenson 1996). The local rate of spread of P. australis is correlated with development and shoreline hardening (McCormick et al. 2011)

Twelve of 15 recent specimens tested from the Chesapeake Bay region were the introduced haplotype M (Saltonstall 2002b). In Chesapeake Bay, based on Saltonstall's surveys (Saltonstall 2002a; Saltonstall 2002b; Meadows and Saltonstall 2007) and the historical data presented here, native populations can be assumed to be rare and localized.

History References - Aikin 1837; Barton 1818; Beaven and Oosting 1939; Bigelow 1814; Brereton 1831; Brown et al. 1987; Burk 1878; Chambers et al. 1998; Chapman 1860; Curtis 1867; Darlington 1853; Elliott 1824; Erlanson 1924; Gray 1848; Gronovius 1739; Hitchcock and Standley 1919; Hitchcock 1935; Holm et al. 1977; Langlois 1887; Marks et al. 1994; Martindale 1875; Metzler and Rozas 1987; Mountford 1997; Potomac-Side Naturalists Club 1867; Pursh 1814; Redmond 1932; Reveal 1983; Rice and Stevenson 1996; Saltonstall 2002a; Saltonstall 2002b; Shreve et al. 1910; Sollers 1888; Tatnall 1860; Torrey 1823; Tucker 1990; Walter 1788; Ward 1881.

Invasion Comments

First Record- Phragmites australis was present in Chesapeake Bay, at least as early as the late 17th century (Moutford 1997 personal communication). It is not known whether the early populations were native or introduced. We consider the 1883 collection from Chesapeake Beach MD to mark the beginning of the drastic range expansion of P. australis in the Bay.

Ecology

Environmental Tolerances

	For Survival		For Reproduction
	Minimum	Maximum	Minimum	Maximum
Temperature (ºC)			10.0	30.0
Salinity (‰)	0.0	40.0	0.0	20.0
Oxygen	hypoxic
pH	3.9000000000	8.6000000000
	Salinity Range	fresh-poly

Age and Growth

	Male	Female
Minimum Adult Size (mm)	2000.0	2000.0
Typical Adult Size (mm)	3000.0	3000.0
Maximum Adult Size (mm)	4000.0	4000.0
Maximum Longevity (yrs)	6.0	6.0
Typical Longevity (yrs	4.5	4.5

Reproduction

	Start	Peak	End
Reproductive Season
Typical Number of Young Per Reproductive Event
Sexuality Mode(s)
Mode(s) of Asexual Reproduction
Fertilization Type(s)
More than One Reproduction Event per Year
Reproductive Startegy
Egg/Seed Form

Impacts

Economic Impacts in Chesapeake Bay

Economic Impacts Outside of Chesapeake Bay

Invasive populations of Phragmites australis (Common Reed) are known from ME to SC, inland in the Great Lakes region,and along the Gulf Coast (Hauber et al. 1992, Marks et al. 1994; Stalter 1994). Reported economic impacts througout this range are similar to those listed for Chesapeake Bay. Quantitative studies of the impacts of P. australis on wetland functions are just beginning, and may result in a re-assessment of the generally negative view of this plant in Eastern North America (Chambers et al. 1999).

Phragmites australis has historically been an important species in many human cultures, as building and roofing material, for matting, and as fodder for animals. It is used in Europe for paper and cellulose production, and is grown as an agricultural crop (Haslam 1972; Holm et al. 1977), but appears to have little positive economic importance in the United States. In Europe, and western North America where reed populations are stable, they are widely regarded as favorable to fisheries and wildilife, and their decline is viewed with alarm (Marks et al. 1994).

References - Chambers et al. 1999; Haslam 1972; Hauber et al. 1992, Holm et al. 1977; Marks et al. 1994; Stalter 1994

Ecological Impacts on Chesapeake Native Species

The rapid expansion of the range and abundance of Phragmites australis (Common Reed) in the Chesapeake Bay region in the late 20th century was cited by two local botanists as the single largest change in Chesapeake Bay wetland communities (Sipple 1995; Silberhorn 1995). Expansion of the area occupied by P. australis was noted in a comparison of aerial photographs of 7 Chesapeake Bay marshes, from the 1930s to the 1990s (Rice et al. 2000). While P. australis has long been regarded as having a negative impact on Atlantic wetlands, quantitative studies of the ecological attributes and function of P. australis marshes on the East Coast only began in the late 1990s. Both native and introduced populations of P. australis exist in the Chesapeake Bay region (Saltonstall 2002a). Invasive populations (haplotype M) have higher growth rates, including asexual reproduction, than native clones (haplotypes AC and F) in freshwater, and at salinities up to 23 ppt. Native clones are less tolerant of saline waters than the invasive forms (Vasquez et al. 2005). Native populations are presumed to be more stable and less characteristic of disturbed habitats than natives, but detailed comparative studies of the genotypes are limited.

Competition - Descriptions of invasions of Phragmites australis from the eastern US presumably refer to the introduced Eurasian haplotype M: (e.g.) 'Phragmites is typically the dominant species in areas that it occupies...and often forms dense monospecific stands' (Marks et al. 1994). The buildup of litter and dense mat of rhizomes and roots discourages competitors; as does shading from the tall shoots. P. australis colonies are well known to invade adjacent plant communities, including Spartina (Cordgrass) spp. marshes, stands of Typha spp., (Cattails), and adjacent upland communities (Flowers 1993; Marks et al. 1994; Fofonoff personal observation). The invasive haplotype has probably replaced native genotypes over much of the Atlantic Coast of North America (Saltonstall 2002a). Greenhouse studies indicate that the invasive form has higher growth rates than native genotypes in fresh- and brackish water conditions (Vasquez et al. 2005).

Disturbed wetlands, including ditched, diked and constructed marshes, appear to be especially prone to invasion by P. australis. Restriction of tidal flow in CT marshes resulted in the replacement of the dominant grasses Spartina spp. by P. australis, restoration of normal tidal flow resulted in reduced P. australis growth and the return of Spartina spp. (Roman et al. 1984). Eleven of 15 constructed wetlands in southeastern VA (all but 1 in or near tidal waters) were colonized by P. australis within 12 years of construction, and are expected to be eventually dominated by this plant (Havens et al. 1997). Along the tidal Patuxent River, colonies of P. australis formed in areas disturbed by rapid siltation from farm runoff and by railroad construction (Rice and Stevenson 1996). Ditching of marshes in the Hackensack Meadowlands NJ has facilitated P. australis invasions into Spartina-dominated regions by decreasing soil hydrogen sulfide content (Bart and Hartman 2000). However, expansion of P. australis has been seen in less disturbed wetlands as well (Marks et al. 1994; Rice and Stevenson 1996; Stalter et al. 1994). In Hog Island Marsh, Smithsonian Environmental Research Center, Edgewater MD, a comparison of present distribution with a vegetation map made in 1973 (Williamson 1974) indicates that P. australis has gone from ~5% of the marsh area to ~20-25% (Fofonoff 1997 personal observation) in 24 years. McCormick et al. (2010) estimated that the area domindated by P. australis, in the Rhode River, has increased about 25X since 1972.

Removal of P. australis from nontidal wetlands, adjacent to the Bay, through burning and herbicides led to increases in plant diversity. However, P. australis began to recolonize the wetlands several years after treatment (Ailstock et al 2001). Removal experiments (using hand cutting, mechanical mowing, and herbicides alone and in combination) in Connecticut River tidal fresh (non-tidal) marshes similarly resulted in a rapid increase in plant diversity, followed by gradual regrowth of P. australis (Farnsworth and Meyerson 1999).

This species is listed as highly invasive in DE, MD, and VA (Cooley 1993; Delaware Natural Heritage Program 1998; Virginia Department of Conservation and Recreation 1999).

Food/Prey - Phragmites australis is eaten or ingested by a variety of fungi, insects, and vertebrates, but in North America, animal grazing is insufficient for biological control (Marks et al. 1994). Haslam (1972) gives a long list of insects and fungi which feed on P. australis in Europe. This reed appears to be not be a preferred food as a living plant, and its detritus is also refractory (Marks et al. 1994). However, while stems break down slowly, leaves break down faster, entering the food chain before the start of the next growing season in CT tidal marshes. (Fell et al. 1998). Species composition of invertebrates found in bags of plant litter in Spartina-dominated and Phragmites-dominated marshes differed both between marshes and with the type of plant litter used. Gammarus tigrinus was more abundant in the 'Spartina' marsh while the polychaete Hobsonia florida was more common in the Phragmites marsh. Chironomid larvae in both marshes were 3 times more abundant on Spartina litter than on Phragmites (Fell et al. 1998). Abundance and diversity of soil invertebrates in nontidal wetlands adjacent to the Bay, were not affected by removal of P. australis (Ailstock et al. 2001).

Replacement of Spartina spp. and other endemic plants by P. australis is thought to decrease the foraging value of a marsh to fishes (Havens et al. 1997; Roman et al. 1984), but we have not found experimental evidence of this hypothesis. One field study in the Connecticut River estuary (CT) found few differences in macroinvertebrate abundance and little difference in the gut contents of Fundulus heteroclitus (Mummichogs) between marshes dominated by Spartina alterniflora (Smooth Cordgrass) and those dominated by P. australis (Fell et al. 1998). Other studies indicate differences of 10-25% in invertebrate density and species richness between Phragmites and Spartina spp. (NJ- Angradi et al. 2001), no differences in overall nekton (fish and shrimp) biomass or species richness (Chesapeake Bay- Meyer et al. 2001), no differences in adult nekton, but fewer larvae in Phragmites (NJ- Able and Hagan 2000). Observed differences in animal abundance reflect habitat as well as food quality. Available information so far suggests that foodweb differences between P. australis and other marsh communities are small (Chambers et al. 1999).

One important salt marsh herbivore, Littoraria irrorata feeds less on P. australis than on Spartina alterniflora, both because of the tougher leaves of Phragmites, and because of a deterrent chemical compound (Hendricks et al. 2011).

However, further field and experimental studies in a variety of tidal wetland environments will be needed to assess the effect of P. australis invasions on estuarine foodwebs.

Habitat Change - Phragmites australis stands have been traditionally viewed as less diverse in fauna than other marsh types (Marks et al. 1998). However, several studies have found few differences in animal abundance and diversity between P. australis marshes and other wetland communities:

1.Soil invertebrates, nontidal Chesapeake bay fresh (non-tidal) marshes, P. australis vs. diverse plant community (Ailstock et al. 1998).

2. Benthic invertebrates and nekton, Connecticut River estuary, P. australis vs. Spartina spp. (Fell et al. 1998).

3. Adult fishes, Mullica River NJ, P. australis vs. Spartina spp. (Able and Hagan 2000).

4. Nekton (fishes and shrimps), upper Chesapeake Bay, P. australis vs. Spartina spp. (Meyer et al. 2001).

5. Blue Crabs (Callinectes sapidus) did not differ in abundance between Spartina and Phragmites marshes (Long et al. 2011).

In all the above cases, few or no significant differences were found in abundance or species composition between P. australis and uninvaded plant communities.

In choice experiments, Uca pugnax (Fiddler Crabs), Palaemonetes pugio (Grass Shrimp), and Fundulus heteroclitus (Mummichogs) showed no consistent preferences for P. australis vs. Spartina. Predation rates of F. heteroclitus on P.pugio did not differ between the two plant types (Weis and Weis 2000).

However, Angradi et al. (2001) found differences in invertebrate community composition between Spartina spp. and P. australis marshes in the Mullica River NJ, with higher abundance and species richness in the Spartina spp. marshes, which they suggested was due to the greater frequency of standing water pools at low tide and greater stem density (more high-tide refugia). Numbers of larval and juvenile fishes were also lower in the Mullica Rivers P. australis marshes (Able and Hagan 2000), possibly also because of reduced surface water. Weinstein and Balletto (1999) argue that P. australis raises marsh levels and smooths microtopography, reducing nekton access to the marsh surface, reducing tidal exchange, fragmenting stands of Spartina spp. and other marsh vegetation, and potentially reducing marsh biodiversity. They note that comparative estimate of fish populations in marshes should take into account not just density per unit of water area, but also the amount of usable water in different marsh types. Hunter et al. (2006) found decreased abundance of F. heteroclitus and F. luciae in mature Phragmites marshes in the Mid-Atlntic region, as did Osgood et al.(2003) in CT marshes.

Phragmites australis marshes have long been assumed to have reduced mammal and bird diversity. A study in CT tidal marshes did find reduced numbers of several bird species [Ammodramus maritimus (Seaside Sparrow), Egretta thula (Snowy Egret), Butorides striatu (Green-backed Heron), Anas platyrhynchos, A. rubripes (Mallard and Black Ducks), Rallus limicola (Virginia Rail), Catoptrophorus semipalmatus (Willet) and other sandpipers) in Phragmites marshes compared with Spartina spp. (Benoit et al. 1999). Another study in northern MA tidal marshes found little effect of P. australis on bird abundance (Holt and Buschbaum 2000). One occasionally troublesome native species which uses P. australis stands extensively for cover and roosting is Agaleius phoeniceus (Red-Winged Blackbird) (Marks et al. 1994). Phragmites australis does provide cover and limited food for a variety of animals, but it is traditionally regarded as inferior to brackish Spartina marshes, or diverse freshwater marshes as wildlife habitat. In areas where P. australis populations have been stable (Western North America; Europe), reed stands are considered desirable wildlife habitats, and their decline is viewed with alarm (Marks et al. 1994).

Phragmites australis potentially can alter the physical profile and chemical functions of marshes by depositing litter, restricting water exchange, absorbing nutrients, and oxygenating sediments (Bart and Hartman 2000; Chambers et al. 1999). Rhizome connections permit plants on the edge of the colonies to spread into anoxic sulfide-rich sediments, and gradually oxygenate these sediments, permitting further expansion of the colony (Bart and Hartman 2000). Phragmites australis' litter deposition raises marsh levels, decreasing water cover, and possibly decreasing access by nekton (Weinstein and Balletto 1999), but also potentially protecting marshes and shorelines against sea-level rise. Short-term and storm sediment deposition rates in Chesapeake Bay marshes (MD Eastern Shore) were much higher (1.6-1.9X) in P. australis than in Spartina spp. marshes. In addition, below-ground accumulation, due to rhizome growth, was 2.5X higher in the P. australis marshes (Rooth and Stevenson 2000).

Control methods used in parks and refuges, including herbicides, cutting, flooding, burning are likely to have adverse short-term effects on resident native biota (Ailstock et al. 2001; Marks et al. 1994).

Hybridization- Limited hybridization between native and introduced genotypes of P. australis has been observed in brackish York River tributaries (Wu et al. 2015).

References - Able and Hagan 2000; Ailstock et al. 2001; Angradi et al. 2001; Bart and Hartman 2000; Chambers et al. 1999; Cooley 1993; Delaware Natural Heritage Program 1998; Fell et al. 1998; Flowers 1993; Haslam 1972; Havens et al. 1997; Holt and Buschbaum 2000; Marks et al. 1994; Meyer et al. 2001; Rice and Stevenson 1996; Roman et al. 1984; Rooth and Stevenson 2000; Stalter et al. 1994; Virginia Department of Conservation and Recreation 1999; Weinstein and Balletto 1999; Weis and Weis 2000; Williamson 1974

Ecological Impacts on Other Chesapeake Non-Native Species

The rapid late-20th-century increase in abundance and range of Phragmites australis (Common Reed) in Chesapeake Bay and along most of the East Coast potentially affects introduced species as well as native ones.

Competition, Habitat change - A local plant biomass dominant and competitor, Typha angustifolia (Narrow-Leaved Cattail), is probably introduced to North America (Stuckey and Salamon 1987). Typha sp. (native T. latifolia and T. angusitfolia). like P. australis, was found to invade newly constructed wetlands, but was found in only 5 of 15 wetlands in VA (Havens et al. 1997). Typha spp. tend to grow in deeper water, and closer to the water edge of marshes than P. australis (Haslam 1972). However, replacement of a stand of T. angustifolia by P. australis has been occurring since 1999 in Hog Island Marsh, Smithsonian Environmental Research Center (Fofonoff, personal observations). Dense stands of P. australis in marsh and shore areas may have displaced other introduced plants as well as native ones.

Food/Prey - Larvae of a Eurasian noctuid moth, Rhizedra lutosa (Greater Wainscot Moth); recently recorded from Chesapeake and Delaware Bay; feed on P. australis (Mikkola and LaFontaine 1994; Tipping 1997 personal communication), but only on rhizomes and stems in dry soil (Bretherton et al. 1983; Van den Toorn and Mook 1982). At least 5 additonal exotic Phragmites feeding insects (Chaetococcus phragmitis; Lasioptera hungarica; Lipara rufitarus; Sclerocona acutella; Tetramesa phragmitis) have been collected in Chesapeake Bay tidal wetlands (Blossey and Weber 2000; Wagner et al. 2003), and 13 additional recently introduced Phragmites feeders have been found in the northeastern U.S. (Tewksbury et al. 2002). The introduced Myocastor coypus (Nutria) sometimes eats substantial quantities of P. australis, which comprised as much as 33% of the diet (~6% annual average) (Willner et al. 1979).

The refractory nature of P. australis' detritus, which has been supposed to adversely affect marsh foodwebs (Marks et al. 1994) could affect introduced fishes and invertebrates in fresh-oligohaline tidal marshes, as well as native ones.

References- Blossey and Weber 2000; Bretherton et al. 1983; Fofonoff, personal observations; Haslam 1972; Havens et al. 1997; Marks et al. 1994; Mikkola and LaFontaine 1994; Stuckey and Salamon 1987; Tewksbury et al. 2002; Tipping 1997 personal communication; Van den Toorn and Mook 1982; Wagner et al. 2003Willner et al. 1979

References

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