Introduced Species in Oregon Estuaries

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Species to Watch

Species by Taxon

Invaders that could be expanding their ranges in Oregon estuaries

If you should find one of these nonindigenous species in a new estuary, save the specimen and call 1-866-INVADER or the Oregon Department of Fish and Wildlife (541-867-0300), a marine extension agent or the contact person or agency listed below. It is important for a trained specialist to positively identify the intact specimen. Your cooperation could help document the range expansion of these invaders and prevent the establishmen of new ones. Once an invasive species reproduces and establishes large viable populations it is impossible to eradicate. Please note that it is illegal to transport live specimens of certain invasive species such as Chinese Mitten crabs.

Japanese eel grass Zostera japonica was probably introduced as live packing material for Japanese oysters. Its thin, narrow blades and high intertidal distribution distinguishes it from the native Zostera marina. Zostera japonica provides habitat for invertebrates and food for dabbling ducks. Its roots trap sediment, thus raising the elevation of mudflats. Birds help spread this species to other estuaries. Zostera japonica is presently found in the Coquille, Coos, Yaquina, Siletz, Salmon, Tillamook, Netarts, and Nehalem estuaries and Young's Bay. (Photo courtesy of Sandy Wylie-Echeveria)

Jim Kaldy (541 867 4026)
Environmental Protection Agency,
2111 SE Marine Science Drive Newport OR 97365 5260

The Atlantic marsh grasses of the genus Spartina were intentionally planted in Puget Sound for cattle grazing, dike stabilization and waterfowl habitat. They were also used to keep Atlantic oysters moist during transport. The spreading root system of Spartina alterniflora traps fine sediment, causing mudflats to rise and become high marsh habitats. This ability of Spartina alterniflora to modify habitat is threatening oyster beds in Willapa Bay, WA. A plant hopper is currently being tested as a possible biological control agent for this species. In Oregon, a patch of Spartina alterniflora started in the Siuslaw estuary. It was eradicated by diggin and the use of herbicides. (Photo courtesy of Kirsten Holsman) For more information see:

http://www.willapabay.org/~coastal/nospartina/
Oregon Spartina Response Plan: http://clr.pdx.edu/publications.html

Oregon Department of Agriculture 503-986-4621
635 Capitol St. NE
Salem, OR 97301-2532

Another Atlantic marsh grass Spartina patens exists in the Siuslaw estuary. So far, it has only been found on Cox Island. Volunteers and employees of The Nature Conservancy are controlling this species by covering it with black plastic sheets. Half of the area was under control at the end of the summer of 2003. If you want to help with this eradication effort, contact Debbie Pickering at 541-994-5564.

Oregon Department of Agriculture 503-986-4621
635 Capitol St. NE
Salem, OR 97301-2532

The purple varnish clam or purple mahogany clam, Nuttallia obscurata, is a native of Japan and Korea. Its thin shell exhibits distinct purple color on the inside and a shiny, light brown cover on the outside. It was introduced into British Columbia most likely as laravae via ballast water in the late 1980's. From there, its planktonic larvae spread south in ocean currents and colonized Washington and Oregon bays. Nuttallia obscurata is found in sediment ranging from cobble to muddy sand in the upper mid-intertidal zone, just above the range of the native littleneck clam, Prothaca staminea. It is often associated with freshwater seeps and is preyed on by the native red rock crab, Cancer productus. In Oregon, Nuttallia obscurata is currently found in Coos, Alsea, Yaquina, Nestucca, Netarts, Nehalem estuaries. For more information see:

http://faculty.washington.edu/cemills/Nuttallia.html

John Chapman, Hatfield Marine Science Center 541-867-0235
John.chapman@hmsc.orst.edu

Asian clam, Potamocorbula armurensis is currently not known to be in Oregon, but could arrive soon. It was introduced into San Francisco Bay in the 1980's, most likely via ballast water. Very tolerant of low salinities and temperature extremes, this clam anchors itself to soft substrate with byssal threats, forming dense "carpets". In some parts of San Francisco Bay this clam reaches densities up to 10,000 per square meter. The pumping action of Potamocorbula reduced phytoplankton abundance and thus affecting densities of herbivorous shrimp and copepods. For more information see:

http://sfbay.wr.usgs.gov/~resmith/aaasabs.html http://www.fish.wa.gov.au/hab/broc/marineinvader/marine08.html

John Chapman, Hatfield Marine Science Center 541-867-0235
john.chapman@hmsc.orst.edu

The European green crab Carcinus maenas became established in San Francisco Bay prior to 1990 and from there spread both north and south. Large adult green crabs were found in Coos Bay in 1997 and in 1998, a strong new year class colonized estuaries from northern California to the west coast of Vancouver Island. Natural transport of larvae by ocean currents appears to be the mechanism for this range expansion. Breeding populations are currently present in Coos, Yaquina and Tillamook Bay. In 1998, Carcinus maenas was also sighted in the Coquille, Alsea, Salmon, and Netarts estuaries. Green crabs can be distinguished from native crabs by the five triangular teeth behind the eyes. For more information see:

http://www.wa.gov/wdfw/fish/ans/greencrab.htm www.fish.wa.gov.au/hab/broc/marineinvader/marine02.html,

Sylvia Yamada, Zoology Department 541-737-5345 yamadas@science.oregonstate.edu

The Chines mitten crab, Eriocheir sinensis,can be identified by the dense patches of hair on its white-tipped claws. It is established in the San Francisco Bay watershed and could arrive in Oregon through natural larval dispersal and by intentional introduction. A single male Japanese mitten crab, Eriocheir japonica, was caught by an sturgeon angler in the Columbia River in 1998. Mitten crabs live in fresh water for 2 to 3 years but adults migrate downstream to estuaries to reproduce. Larvae spend 1-2 month in the plankton before settling on the shore in late spring. Juveniles burrow in stream banks and migrate upstream as they mature. Their burrowing activities causes erosion of river banks and levees. At high densities, they cause damage to fishing nets and water diversion facilities. For more information see:

Larry Cooper, Oregon Department of Fish and Wildlife
503-872-5260, ext. 5347 larry.cooper@state.or.us

The isopod or pillbug, Sphaeroma quoianum, is a native to New Zealand. It arrived in San Francisco Bay early in the 20th Century and spread to Humboldt Bay in the 1930's. It was detected in Coos Bay, Oregon in 1995. This species bores into wood, peat, soft sandstone and styrofoam floats. It is expected that this boring crustacean will continue to spread north.

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