Science Inventory

A tale of two seagrasses: Comparing the science and management of Zostera marina and Zostera japonica in the Pacific Northwest - CERF


Shafer, D., Jim Kaldy, AND J. Gaeckle. A tale of two seagrasses: Comparing the science and management of Zostera marina and Zostera japonica in the Pacific Northwest - CERF. Presented at Coastal Estuarine Research Federation, San Diego, CA, November 03 - 07, 2013.


Federal and state researchers assessed the state of the science to support management decisions for the introduced seagrass species Zostera japonica on the Pacific Coast of North America, finding that there are critical gaps in the information needed to develop optimally effective management strategies. Seagrasses are generally considered to be a cornerstone of estuarine ecosystem health and productivity, yet this benefitial aspect runs counter to concerns over potential ecosystem effects of introduced species. As a result, management strategies by Pacific States range from protection as nursery habitat to eradication. Eradication stratagies for this non-native seagrass are contrary to world-wide conservation efforts for native seagrasses, and may be inconsistent with Federal and State regulations. The review provides recommendations for studies that may provide resource managers with better information to develop appropriate and effective management strategies.


On the Pacific coast of North America, at least two congeners of Zostera occur: native Z. marina, and introduced, Z. japonica. Z. marina is protected by State and Federal laws as essential fish habitat. Z. japonica is considered “invasive” and therefore, ecologically and economically harmful by some, while others consider it benign or perhaps beneficial. Z. japonica does not appear on the Federal or the Oregon invasive species or noxious weed lists. However, California lists it as both an invasive and noxious weed and Washington recently listed it as a noxious weed. We describe the management dynamics in North America with respect to these congener species and highlight the science and policies behind these decisions. In recent years, management strategies at the state level have ranged from protection of Z. japonica as a priority habitat in Washington to eradication in California. In 2011, Washington State reversed its long standing policy to protect Z. japonica and is developing permits for chemical control of this plant. The policy of Z. japonica removal contradicts efforts to conserve and protect seagrass in other regions of the US and around the world. We recommend research actions to assist in the assessment of Z. japonica ecology and the immediate and long-term effects of management actions.


ABSTRACT - SHAFER.PDF   (PDF,NA pp, 42.563 KB,  about PDF)

Record Details:

Product Published Date: 11/07/2013
Record Last Revised: 11/15/2013
OMB Category: Other
Record ID: 263034