The Oregon Spartina Response Plan

Contact Information

Vanessa Howard
vhoward@pdx.edu
Portland State University
Center for Lakes and Reservoirs
PO Box 751- ESR
Portland OR 97207-0751
Ph:503-725-2937
Fax: 503-725-3834

 

Introduction

Several Spartina species threaten to invade Oregon estuaries. Large populations of these cordgrasses, spreading across thousands of acres, have altered mudflat and salt marsh habitat in multiple estuaries in California and Washington. And three species of invasive cordgrasses have been confirmed in British Columbia. Despite control efforts, these existing populations continue to produce seed that can travel via ocean currents to potentially start new infestations.

Pfauth et al. (2003) estimated that about 33,600 acres of Oregon estuaries are colonizable by Spartina. Based on an ODA-funded report (ODA 2000), Spartina costs are anticipated to be about $666/acre. Therefore, potential cost of a Spartina invasion of Oregon estuaries exceeds $22 million per year. There have only been three known populations in the state as of 2007; these have occured on the Siuslaw River (both S. patens and S. alterniflora) and in Coos Bay (S. alterniflora).

The Oregon Spartina Response Plan [4.5 Mb pdf], created by Portland State University (PSU) Center for Lakes and Reservoirs with funding from the Oregon Department of Agriculture, stresses early detection of new infestations, rapid response to any findings of Spartina and education of the threat and potential losses so as to increase public awareness. Revisions to the orginal response plan, first written in 2003, are now complete.

Implementation

Early detection - Extensive surveys of all Oregon estuaries are conducted on an ongoing basis. Surveys aimed at finding S. alterniflora, S. patens and S. anglica are conducted by air, boat and ground between June and early October (when these three species senescene for the winter). Surveys for S. densiflora will be conducted between December and March since this species, unlike most native plants, remains upright then entire year.

Rapid Response - In 2005, two small populations of S. alterniflora were discovered during early detection surveys - one on the Siuslaw River near Florence and the other in Coos Bay, near Barview.

The sighting in Florence appears to have been re-growth from a previous infestation in the same location, which was treated between 1990-94 and deemed eradicated in 1997 after three years of surveys revealed no signs of re-growth. The regrowth found in 2005 was one solitary clone surrounded by dense high-marsh vegetation in an area with a sandy substrate (left photo below). It was hand dug in August 2005 and showed no signs of regrowth in 2006 or 2007.

The Barview site, located East of the Charleston marina and just North of the Charleston Bridge, was a former dredge-material disposal site which which was restored as salt marsh habitat between 1993-94 (right photo above). After interviewing a number of sources, we believe this was a case of unintentional transplantation - native plant plugs harvested from the Siuslaw River probably harbored live rhizomes of the cordgrass from that site's earlier infestation . Manual removal at Barview was conducted by an Oregon Youth Conservation Corps in 2005, with oversight from the South Slough National Estuarine Research Reserve. Only a small amount was found and removed in 2006. No regrowth was found in 2007.

We recommend yearly monitoring at these specific sites for 7-10 years following the removal of the last regrowth.

Education and outreach has focused on groups such as: local watershed councils, land managers, oyster growers and soil & water conservation districts. Additionally, the Spartina Dispersal Study, which used drift cards to demonstrate potential seed dispersal from known infestations in CA & WA, reached a huge number of people - alerting them to the threat of invasive cordgrasses and invasive species in general.

If you know of an organization which may be interested in hearing a presentation on this issue, please feel free to contact us (information above).

Resources

Oregon Spartina Response Plan -2007 (4.5 Mb pdf) Prepared by Vanessa Howard, Mary Pfauth, Mark Sytsma and Dennis Isaacson

Oregon Spartina Response Plan (441 Kb pdf)
March 2003. Mary Pfauth, Dennis Isaacson, and Mark Sytsma