Smooth Cordgrass (Spartina alterniflora) Thomas Pham Fish 423 Aquatic Invasion Ecology Final Report: Fall 2011 Diagnostic information Scientific name Order: Poales Family: Poaceae Genus: Spartina Species: alterniflora Common names: Smooth cordgrass, saltmarsh cordgrass, saltwater cordgrass, Atlantic cordgrass, oystergrass Basic identification key Using the Key to West Coast Spartina Species’ dichotomous key one can properly identify Spartina alterniflora among the other Spartina species. According to the key S. Figure 1. Spartina alterniflora at a salt marsh in East alterniflora has leaf blades when fresh, Sandwich, Massachusetts. Nelson DeBarros @ internodes that are fleshy, a leaf width that is at USDA-NRCS PLANTS Database most 25mm, reddish streaks or red pigment often present at the base of young and healthy Life-history and basic ecology shoots. Additionally, the USDA Natural Resources Conservation service describes S. Life cycle, environmental optima and tolerances alterniflora as a grass with long hollow Spartina alterniflora is a perennial rhizomatous rhizomes. It ranges from 2 to 7 feet tall and has grass that grows in intertidal zones (Subudhi et leaf blades that are around 12-20 inches long. al. 2009). In specific it grows in salt marsh, mud Lastly, during the months of September and flat, and sand flat habitats. It prefers habitats October, seedheads are present that are around with low or moderate wave action. Furthermore, 12 inches in length and can carry spikes that this plant is highly adapted to grow in very high carry 12-15 spikelet seeds. salinity concentrations and can grow in water salinities up to 60‰ (Bertness 1991). It can grow in a variety of substrates including: sand, silt, cobble, clay, and gravel. S. alterniflora is a spikelets which hold seeds that generally develop in July through October. Pollination is achieved by wind and seeds are dispersed primarily dispersed by water which can carry the seeds long distances due to tides and currents. Vegetative fragmentation is the process in which segments of the plant break off and form a new Figure 2. An inundated Spartina alterniflora marsh plant but is genetically identical to the original. particularly persistent species that tolerate a Lastly, S. alterniflora can also spread clonally varying degree of abiotic conditions. It can by rhizomes. When pieces of rhizome root break survive in complete submersion of water for up off, they can sometimes regrow into a new plant to 12 hours and in water with pH levels ranging that is also a genetic clone to the original. from 4.5 to 8.5 (Landin 1991). Nutrient supply is a limiting factor for S. alterniflora. Bursesh et Current geographic distribution al. (1980) found that nitrogen is an important determining factor for growth and productivity Distribution in the United States for S. alterniflora in Louisiana salt marshes. According to the United States Additionally, they observed a greater influence Department of Agriculture Natural Resources of nitrogen added to inland meadows compared Conservation Service Spartina alterniflora to streamside meadow. currently resides among 21 different states including: Alabama, California, Connecticut, Reproductive strategies Delaware, Florida, Georgia, Louisiana, Spartina alterniflora has three methods Massachusetts, Maryland, Maine, Mississippi, of reproduction that involve both sexual and North Carolina, New Hampshire, New Jersey, clonal processes. It reproduces by seed, rhizome, New York, Oregon, Rhode Island, South or vegetative fragmentation (Daehler and Strong Carolina, Texas, Virginia, and Washington. 1994). It produces inflorescences containing Figure 3. Current distribution of Spartina alterniflora across the United States (USGS) Spartina alterniflora is non-native to the state of History of invasiveness Washington. There are three main regions of Washington State that S. alterniflora has Spartina alterniflora is a rhizomatous established populations: Puget Sound, Grays grass native to the Atlantic and Gulf coast Harbor, and Willapa Bay. It is believed that it marshes of North America (Xiao et al. 2011). It was introduced by accident into Willapa Bay dominates the marshes in its native range. S. around the late nineteenth century as a alterniflora has been introduced to new regions hitchhiker with oysters shipped from the both intentionally and unintentionally. It has Atlantic coast (Dennis et al. 2011). Seeds of S. been introduced to the west coast of the United alterniflora likely were inadvertently brought States, Great Britain, the Atlantic coast of into the same barrels that the oysters were being Europe, and New Zealand (Marchant et al 1970; shipped in. Furthermore, Stiller and Denton Partridge et al 1987; Hitchcock et al. 1969). (1995) performed random amplified Distribution in Washington State polymorphic DNA (RAPD) analysis to determine the genetic history of the S. fish and wildlife habitat”. It is currently alterniflora populations in Willapa. Their data classified as a Class A noxious weed meaning suggests that the entire S. alterniflora population that eradication of this plant is required by law. inhabiting the Willapa Bay region descended Unlike the populations in Willapa Bay, S. from a single introduced clonal colony. The alterniflora was intentionally introduced into establishment of this population was spread Puget Sound by landowners. It was introduced primarily by seed dispersal. Rhizome and into Padilla Bay sometime between 1940 and vegetative fragmentation contributed little to the 1946 by the Dike Island Gun Club in order to spread in this region (Civille et al. 2005). S. stabilize the land that the gun club was on alterniflora was recognized as a pest weed in (Parker and Aberle 1979). A hybrid species Willapa Bay and was placed on Washington Spartina anglica is able to hybridize with S. State’s noxious weed list in 1989. The alterniflora and was introduced to Puget Sound Washington State Noxious Weed Control Board in 1961 (Hacker et al. 2001). defines a noxious weed as “the traditional, legal Populations of S. alterniflora also exist in Grays term for any invasive, non-native plant that Harbor. However, the pathway of introduction threatens agricultural crops, local ecosystems of of it is not known for this particular region. In addition to S. alterniflora, Spartina densiflora is also found here. Distribution in Oregon S. alterniflora is also present in the State of Oregon, although at much lower densities than observed in Washington State. As of now three infestations of S. alterniflora have been observed in Oregon. One of the colonization’s took place in the Siuslaw River in Florence, Oregon. It was intentionally planted around the 1970’s at the Port of Siuslaw (Frenkel 1990, Strong and Ayres 2009). S. alterniflora was also detected in Coos Bay in 2005 at a dredge material disposal site (Oregon Figure 4. Distribution of Spartina alterniflora sites in Response Plan 2007). It is believed that Washington State 2010 (WSDA) unintentional transplantation was the vector for the introduction of it into Coos Bay. Finally, the third and most recent infestation of Factors influencing establishment and spread S. alterniflora in Oregon was discovered in 2008 There are a number of factors that influence the at Youngs Bay (ODA Plant Division Annual establishment of Spartina alterniflora. One Report 2010). However, early detection found factor that actually slowed the rate of invasion of the patch to be only 800 square feet in size and it into the Pacific Northwest was Allee effects was dealt with quickly. As of 2010 no new which is “a positive relationship between any plants have been found in Youngs Bay. component of fitness of a species and density of conspecifics” (Stephens et al. 1999). Davis et al. Invasion process (2004) conducted an experiment and discovered that pollen limitations can cause an Allee effect Pathways, vectors and routes of introduction on S. alterniflora meaning that it can slow its Spartina alterniflora historically has rate of colonization. Additionally, without Allee invaded the Pacific Northwest by both effects S. alterniflora would have spread across intentional and unintentional introductions. The Willapa Bay at a much higher rate (Taylor et al. initial pathway that has led to S. alterniflora’s 2004) and likely would have covered the entire invasion into Washington has been through bay a long time ago (Strong and Ayres 2009). aquaculture, in particular the stocking of oysters. S. alterniflora was introduced into Willapa Bay Potential ecological and/or economic impacts in the late nineteenth century as part of the Spartina alterniflora is an ecosystem oyster cultivation efforts (Dennis et al. 2011). S. engineer. Jones et al. (1994) coined the term alterniflora seeds hitchhiked along with oyster ecosystem engineer and defined it as: shipments by train from Atlantic marshes where “organisms that directly or indirectly modulate its native region lay. the availability of resources (other than In addition to unintentional introductions, there themselves) to other species, by causing physical have also been intentional introductions of S. state changes in biotic or abiotic materials. In so alterniflora. In its native range, S. alterniflora is doing they modify, maintain and/or create valued for its ability to alleviate erosion habitats”. S. alterniflora alters the ecosystem in (Simenstad and Thom. 1995). The very same which it habitats by a number of different properties have led to intentional introduction means. It can change