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.

alterniflora has leaf blades when fresh,

internodes that are fleshy, a leaf width that is at

most 25mm, reddish streaks or red pigment

often present at the base of young and healthy

shoots. Additionally, the USDA Natural

Resources Conservation service describes S.

alterniflora as a grass with long hollow

rhizomes. It ranges from 2 to 7 feet tall and has

leaf blades that are around 12-20 inches long.

Lastly, during the months of September and

October, seedheads are present that are around

12 inches in length and can carry spikes that

carry 12-15 spikelet seeds.

Life-history and basic ecology

Life cycle, environmental optima and tolerances

Spartina alterniflora is a perennial rhizomatous

grass that grows in intertidal zones (Subudhi et

al. 2009). In specific it grows in salt marsh, mud

flat, and sand flat habitats. It prefers habitats

with low or moderate wave action. Furthermore,

this plant is highly adapted to grow in very high

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

Figure 1. Spartina alterniflora at a salt marsh in East

Sandwich, Massachusetts. Nelson DeBarros @

USDA-NRCS PLANTS Database

particularly persistent species that tolerate a

varying degree of abiotic conditions. It can

survive in complete submersion of water for up

to 12 hours and in water with pH levels ranging

from 4.5 to 8.5 (Landin 1991). Nutrient supply

is a limiting factor for S. alterniflora. Bursesh et

al. (1980) found that nitrogen is an important

determining factor for growth and productivity

for S. alterniflora in Louisiana salt marshes.

Additionally, they observed a greater influence

of nitrogen added to inland meadows compared

to streamside meadow.

Reproductive strategies

Spartina alterniflora has three methods

of reproduction that involve both sexual and

clonal processes. It reproduces by seed, rhizome,

or vegetative fragmentation (Daehler and Strong

1994). It produces inflorescences containing

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

plant but is genetically

identical to the original.

Lastly, S. alterniflora can also spread clonally

by rhizomes. When pieces of rhizome root break

off, they can sometimes regrow into a new plant

that is also a genetic clone to the original.

Current geographic distribution

Distribution in the United States

According to the United States

Department of Agriculture Natural Resources

Conservation Service Spartina alterniflora

currently resides among 21 different states

including: Alabama, California, Connecticut,

Delaware, Florida, Georgia, Louisiana,

Massachusetts, Maryland, Maine, Mississippi,

North Carolina, New Hampshire, New Jersey,

New York, Oregon, Rhode Island, South

Carolina, Texas, Virginia, and Washington.

Figure 2. An inundated Spartina alterniflora marsh

Figure 3. Current distribution of Spartina alterniflora across the United States (USGS)

History of invasiveness

Spartina alterniflora is a rhizomatous

grass native to the Atlantic and Gulf coast

marshes of North America (Xiao et al. 2011). It

dominates the marshes in its native range. S.

alterniflora has been introduced to new regions

both intentionally and unintentionally. It has

been introduced to the west coast of the United

States, Great Britain, the Atlantic coast of

Europe, and New Zealand (Marchant et al 1970;

Partridge et al 1987; Hitchcock et al. 1969).

Distribution in Washington State

Spartina alterniflora is non-native to the state of

Washington. There are three main regions of

Washington State that S. alterniflora has

established populations: Puget Sound, Grays

Harbor, and Willapa Bay. It is believed that it

was introduced by accident into Willapa Bay

around the late nineteenth century as a

hitchhiker with oysters shipped from the

Atlantic coast (Dennis et al. 2011). Seeds of S.

alterniflora likely were inadvertently brought

into the same barrels that the oysters were being

shipped in. Furthermore, Stiller and Denton

(1995) performed random amplified

polymorphic DNA (RAPD) analysis to

determine the genetic history of the S.

alterniflora populations in Willapa. Their data

suggests that the entire S. alterniflora population

inhabiting the Willapa Bay region descended

from a single introduced clonal colony. The

establishment of this population was spread

primarily by seed dispersal. Rhizome and

vegetative fragmentation contributed little to the

spread in this region (Civille et al. 2005). S.

alterniflora was recognized as a pest weed in

Willapa Bay and was placed on Washington

State’s noxious weed list in 1989. The

Washington State Noxious Weed Control Board

defines a noxious weed as “the traditional, legal

term for any invasive, non-native plant that

threatens agricultural crops, local ecosystems of

fish and wildlife habitat”. It is currently

classified as a Class A noxious weed meaning

that eradication of this plant is required by law.

Unlike the populations in Willapa Bay, S.

alterniflora was intentionally introduced into

Puget Sound by landowners. It was introduced

into Padilla Bay sometime between 1940 and

1946 by the Dike Island Gun Club in order to

stabilize the land that the gun club was on

(Parker and Aberle 1979). A hybrid species

Spartina anglica is able to hybridize with S.

alterniflora and was introduced to Puget Sound

in 1961 (Hacker et al. 2001).

Populations of S. alterniflora also exist in Grays

Harbor. However, the pathway of introduction

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

Response Plan 2007). It is believed that

unintentional transplantation was the vector for

the introduction of it into Coos Bay.

Figure 4. Distribution of Spartina alterniflora sites in

Washington State 2010 (WSDA)

 

Finally, the third and most recent infestation of

S. alterniflora in Oregon was discovered in 2008

at Youngs Bay (ODA Plant Division Annual

Report 2010). However, early detection found

the patch to be only 800 square feet in size and

was dealt with quickly. As of 2010 no new

plants have been found in Youngs Bay.

Invasion process

Pathways, vectors and routes of introduction

Spartina alterniflora historically has

invaded the Pacific Northwest by both

intentional and unintentional introductions. The

initial pathway that has led to S. alterniflora’s

invasion into Washington has been through

aquaculture, in particular the stocking of oysters.

S. alterniflora was introduced into Willapa Bay

in the late nineteenth century as part of the

oyster cultivation efforts (Dennis et al. 2011). S.

alterniflora seeds hitchhiked along with oyster

shipments by train from Atlantic marshes where

its native region lay.

In addition to unintentional introductions, there

have also been intentional introductions of S.

alterniflora. In its native range, S. alterniflora is

valued for its ability to alleviate erosion

(Simenstad and Thom. 1995). The very same

properties have led to intentional introduction

into Washington and Oregon. Furthermore, it

has the ability to trap sediment very well. It has

been introduced into New Zealand because of

this property as a tool for estuary restoration

(Partridge 1987).

Factors influencing establishment and spread

There are a number of factors that influence the

establishment of Spartina alterniflora. One

factor that actually slowed the rate of invasion of

it into the Pacific Northwest was Allee effects

which is “a positive relationship between any

component of fitness of a species and density of

conspecifics” (Stephens et al. 1999). Davis et al.

(2004) conducted an experiment and discovered

that pollen limitations can cause an Allee effect

on S. alterniflora meaning that it can slow its

rate of colonization. Additionally, without Allee

effects S. alterniflora would have spread across

Willapa Bay at a much higher rate (Taylor et al.

2004) and likely would have covered the entire

bay a long time ago (Strong and Ayres 2009).

Potential ecological and/or economic impacts

Spartina alterniflora is an ecosystem

engineer. Jones et al. (1994) coined the term

ecosystem engineer and defined it as:

“organisms that directly or indirectly modulate

the availability of resources (other than

themselves) to other species, by causing physical

state changes in biotic or abiotic materials. In so

doing they modify, maintain and/or create

habitats”. S. alterniflora alters the ecosystem in

which it habitats by a number of different

means. It can change nutrient cycling,

hydrology, sediment deposition patterns, and

furthermore it can transform open intertidal

mudflats into elevated meadows filled with

nothing but S. alterniflora (Crooks 2002). These

impacts have led to significant change in the

landscape of estuaries and intertidal zones in the

Pacific Northwest. In the absence of S.

alterniflora estuaries in the Pacific Northwest

are generally gently sloped and shallow, bare

mudflats. However, the S. alterniflora can

transform them into steep and deep tidal

channels. Furthermore, the once bare mudflats

can become completely covered in meadows of

S. alterniflora. In addition, it has the ability to

increase sedimentation and decrease the effects

of wave action (Gleason et al. 1979) while also

causing increased flooding.

S. alterniflora not only affects the abiotic

structure of communities but can also have

impacts on native fauna and flora. It is a robust

invader and can out-compete other species such

as Zostera marina (eelgrass). Not only is this

detrimental to Z. marina but also to the species

that rely on it such various invertebrates

including juvenile Dungeness crab

(Metacarcinus magister) (McMillan et al. 1995).

The loss of Z. marina can also have negatively

cascading effects on Anas Americana (American

wigeon), Anas acuta (Northern Pintail), and

Branta bernicla (Brant) all of which rely on Z.

marina for forage (Oregon Response Plan 2007).

Furthermore, the large colonization of bare

mudflats of S. alterniflora greatly reduces the

open habitat for many different shorebirds and

waterfowl. It is currently listed as a threat to

birds by the American Bird Conservancy. The

disturbance that S. alterniflora can cause on its

habitat may even open up opportunities for other

invasive species. A study by Carr and Dumbauld

(2000) suggests that a non-native crab Carcinus

maenas are more concentrated in areas where

Spartina are found.

S. alterniflora also has the potential to cause

massive economic damage as well. Although it

has not occurred, it has the potential to cause

damage to oyster and commercial fisheries. If

they raise the elevation of the estuaries, they can

become unsuitable for oyster aquaculture.

Oyster farming is a large industry for both

Washington and Oregon State and S. alterniflora

has the potential to cause damage to these

markets by land alterations. Furthermore they

can reduce the prey resources for Oncorhynchus

keta (Chum) in its juvenile stage as well as

Parophrys vetulus (English sole) both of which

are important commercial fish for Washington

and Oregon (Noxious Weed Control Board). In

addition S. alterniflora can also can economic

damage by altering beaches which are important

to the tourism markets for Washington and

Oregon (Oregon Response Plan 2007).

Management strategies and control methods

A large amount of time, money, and

effort has been put into the control and

eradication of Spartina alterniflora in the Pacific

Northwest. In Washington State, management of

S. alterniflora began in the 1990’s (Hedge et al.

2003). In 1995, the WSDA was put in control of

its management. In 2003, the Portland State

University Center for Lakes and Reservoirs

created the Oregon Spartina Response Plan with

the goal of “prevent(ing) the establishment and

spread of any Spartina species in Oregon

estuaries and coastal wetlands”. A number of

different strategies have been used to control S.

alterniflora. Removal by hand has been used but

is limited in a number of ways. It is highly time

consuming to remove because care must be

taken to remove the entire plant. If residual

rhizomes are left behind, they have the potential

to grow back. This strategy has more

effectiveness in controlling younger infestations

than mature (Hedge et al. 2003). Another

method that has been used is mowing. Once

again however, this strategy is also limited. It

was found to be neither effective nor cheap as

sites had to be mowed multiple times to

effectively eliminate it. In addition, herbicides

have also been used. The only authorized

herbicide for control of S. alterniflora by the

Washington Aquatic Plant Management

Program Environmental Impact Statement is

Rodeo whose main active ingredient is

glyphosate. There have been large variations in

its effectiveness ranging from no effect to

complete elimination. The most effective

method of control in Washington has been a

combination of mowing followed up by Rodeo

application after it has regrown to 30-45cm,

although it has been found to be highly costly

(Hedge et al. 2003). One last control method that

has been used is a biological control with the

species Prokelisia marginata (Homopteran plant

hopper). This particular species feeds on

Spartina species, specifically its vascular fluids.

However, Gustafson et al. (2006) tested the

effects of P. marginata grazing on Spartina

biomass and found that it is does not exert strong

top-down control on S. alterniflora.

Literature Cited

Bertness MD (1991). Zonation of Spartina

Patens and Spartina Alterniflora in New

England Salt Marsh. Ecology 72: 138-148.

Buresh RJ, Delaune RD, Patrick WH (1980).

Nitrogen and Phosphorus Distribution and

Utilization by Spartina alterniflora in a

Louisiana Gulf Coast Marsh. Estuaries 3:

111-121.

Carr EM, Dumbauld BR (2000). Status of the

European green crab invasion in

Washington coastal estuaries: can

expansion be prevented? Journal of

Shellfish Research 19 : 629-630.

Civille JC, Sayce K, Smith SD, Strong DR

(2005). Reconstructing a century of

Spartina alterniflora invasion with historical

records and contemporary remote sensing.

Ecoscience 12: 330-338.

Crooks (2002). Characterizing Ecosystem-Level

Consequences of Biological Invasions: The

Role of Ecosystem Engineers. OIKOS 97:

153-166.

Daehler CC, Strong DR (1994). Variable

Reproductive Output Among Clones of

Spartina alterniflora (Poaceae) Invading

San Francisco Bay, California: The

Influence of Herbivory, Pollination, and

Establishment Site. American Journal of

Botany 81: 307-313.

Davis HG, Taylor CM, Lambrinos LG, Strong

DR, Mooney HA (2004). Pollen

Limitations Causes an Allee Effect in a

Wind-Pollinated Invasive Grass (Spartina

alterniflora). PNAS: 101: 13804-13807.

Dennis B, Civille JC, Strong DR (2011). Lateral

spread of invasive Spartina alterniflora in

uncrowded environments. Biological

Invasions 13: 401-411.

Gleason ML, Elmer DA, Pien NC, Fisher JS

(1979). Effects of Stem Density upon

Sediment Retention by Salt Marsh Cord

Grass, Spartina alterniflora Loisel.

Estuaries 2: 271-273.

Gustafson DJ, Kilheffer J, Silliman BR (2006).

Relative Effects of Littoraria irrorata and

Prokelisia marginata on Spartina

alterniflora. Estuaries and Coasts 29: 639-

644.

Hedge P, Kriwoken LK, Patten K (2003). A

Review of Spartina Management in

Washington State, US. Journal of Aquatic

Plant Management 41: 82-90.

Hitchcock CL, Cronquist A, Ownbey M (1969)

Vascular Plants of the Pacific Northwest.

Part 1: Vascular Cryptogams,

Gymnosperms, and Monocotyledons.

University of Washington Press, Seattle,

Washington

Jones CG, Lawton JH, Shachak M (1994).

Organisms as ecosystem engineers. OIKOS

69: 373-386.

Marchant CJ (1970). Evolution in Spartina

(Gramineae) IV. The cytology of S.

alterniflora Loisel. in North America.

Botanical Journal of the Linnean Society

63: 321-326.

McMillan RO, Armstrong DA, Dineel PA

(1995). Comparison of intertidal habitat

use and growth rates of two northern Puget

Sound cohorts of 0+ age Dungeness crab,

Cancer magister. Estuaries 18: 390-398.

Parker RC, Aberle B (1979). A situation report

on the Spartina infestation in northwest

Washington. Unpublished report to the

Washington State Department of game,

Mount Vernon

Partridge TR (1987). Spartina in New Zealand.

New Zealand Journal of Botany 25: 567-

575.

Simenstad CA, Thom RM (1995). Spartina

alterniflora (smooth cordgrass) as an

invasive halophyte in Pacific Northwest

estuaries. Hortus Northwest 6:9-12, 38-40.

Stiller JW, Denton AL (1995). One hundred

years of Spartina altemiflora (Poaceae) in

Willapa Bay, Washington: random

amplified polymorphic DNA analysis of an

invasive population. Molecular Ecology 4:

355-363.

Stephens PA, Sutherland WJ, Freckleton RP

(1999). What is the Allee effect? OIKOs

87: 185-190.

Strong DR, Ayres DA (2009) Spartina

Introductions and Consequences in Salt

Marshes. In: Silliman BR (ed), Grosholz

ED (ed), Bertness MD (ed) Human Impacts

on Salt Marshes: A Global Perspective, 1st

edn. University of California press,

Berkeley, CA.

Subudhi PK, Baisakh N (2011). Spartina

alterniflora Loisel., a halophyte grass model

to dissect salt stress tolerance. In Vitro

Cellular & Developmental Biology – Plant

47: 441-457.

Taylor CM, Davis HG, Civille JC, Grevstad FS,

Hastings A (2004). Consequences of an

Allee effect in the invasion of a pacific

estuary by Spartina alterniflora. Ecology

85: 3254-3266.

Xiao Y, Tang J, Qing H, Zhou C, An S (2011).

Effects of salinity and clonal integration on

growth and sexual reproduction of the

invasive grass Spartina alterniflora. Flora

206: 736-741.

Other key sources of information and

bibliographies

Written Findings of the Washington State

Noxious Weed Control Board (1995)

http://www.nwcb.wa.gov/siteFiles/Spartina_alter

niflora.pdf

Oregon Spartina Response Plan 2007

http://www.clr.pdx.edu/docs/OSRP.pdf

Spartina Eradication Program 2010 Progress

Report

http://agr.wa.gov/PlantsInsects/Weeds/Spartina/

docs/SpartinaReport2010.pdf

Oregon Department of Agriculture Plant

Division Annual Report 2010

http://www.oregon.gov/ODA/PLANT/docs/pdf/

plant_annual_report_2010.pdf?ga=t

West Coast Governors’ Agreement on Ocean

Health Spartina Eradication Action

Coordination Team Work Plan

http://westcoastoceans.gov/Docs/Spartina_Final

_Work_Plan.pdf

Expert contact information in PNW

Kathleen Sayce

P.O. Box 91

Nahcotta, WA 98637

Phone: (360) 665-5292 (H), (360) 642-1166 (W)

ksayce@shorebankpacific.com

Vanessa Howard

Center for Lake and Reservoirs

Portland State University

P.O. Box 751

Portland, OR 97207-0751

Phone: (503) 725-9076

Fax: (503) 725-3834

vhoward@pdx.edu

Nancy Ness

Grays Harbor County

Noxious Weed Board Coordinator

P.O. Box R

Elma, WA 98541

Phone: (360) 482-2265

Fax: (360) 482-2662

nessn@cahnrs.wsu.edu

Kyle Murphy

WSDA Spartina Coordinator

P.O. Box 42560

Olympia, WA 98504

Phone: (360) 902-1923

kmurphy@agr.wa.gov

Current research and management efforts

The state of Washington has devoted a

large amount of time and resources to eradicate

Spartina alterniflora. Since 1995, the

Washington State Department of Agriculture has

spearheaded the eradication of Spartina species.

They have coordinated a number of stakeholders

and entities in working together to manage

Spartina. They have seen great success in

eliminating S. alterniflora as well as other

Spartina species in the state. From a record high

of 9,260 acres of Spartina spp. observed in

2003, the WSDA has reduced that amount to 27

acres as of 2010 (Spartina Eradication Program

2010 Progress Report). The effort continues

although they believe that the last few acres will

be the most difficult to remove. The WSDA

estimates that 7 solid acres of Spartina will

remain in Willapa Bay in 2011, less than 0.05

acres in Grays Harbor, and 5 acres in Puget

Figure 5. Solid acres of Spartina by year statewide based on WSDA estimates. The blue line represents historic

Spartina infestations since 2003. The red line indicates the projected Spartina infestation level through 2014.

Projection assumes continued funding.

Sound. Currently, they are continuing to use

integrated pest management techniques such as

mechanical, chemical, manual control, or a

combination of them as previously described,

although more effort is being put into shoreline

surveillance as the numbers of acres of Spartina

have been greatly reduced.

On September 18, 2006 the governors of

California, Oregon, and Washington announced

the West Coast Governors’ Agreement on Ocean

Health. Through this agreement they called for

collaboration to manage and protect the ocean

and coastal resources along the West Coast.

Through this agreement a Spartina eradication

program was developed with the goal of

eliminating non-native Spartina off of the West

Coast by 2018. This program created a

comprehensive work plan and outlined a number

of tasks in order to achieve the goal of complete

eradication. According to the work plan, they are

working on developing an internet based GIS

(geographic information system) to define the

areas in which Spartina has been eradication.

Overall this agreement has combined the efforts

of California, Oregon, and Washington in

eliminating Spartina spp. With the bulk of the

infestations managed, the remaining work is

synthesizing the collective efforts between

agencies and states.