Intentional Introductions Gone Bad Salt marsh cordgrass (Spartina alterniflora), used as packing material for Atlantic oysters (Crassostrea virginica), has been introduced into Oregon. The cordgrass continues to spread along the Oregon coast, taking over mudflats and disrupting bird migrations. Shipments of the European oyster (Ostrea edulis) were brought from Washington to France to supplement a low native stock. The virus Bonamia ostrea was thought to have accompanied these shipments and ended up destroying the remaining native stock of the European oyster in France. Although the Chinese mitten crab (Eriocheir sinensis) was banned for importation and aquaculture in the U.S. in the late 1980's, the crab was discovered in San Francisco Bay in 1994. The crab's high market value and resistance to the ban by California aquaculturists suggest that the crab may have been intentionally introduced.

Why You Should Care...

Kayaking, clam chowder, nature walks, lobster feasts, waterviews.

If any of these appeal to you, listen up!

Invasive species are a threat to these and more!

In the fall of 2001, a potentially devastating invader called hydrilla (Hydrilla verticillata) was found in Long Pond on Cape Cod. Dubbed, the "Perfect Weed," hydrilla is one of the most aggressive invasive plants now present in the United States. Hydrilla is native to Asia where it coexists with other submerged plants and provides habitat for many aquatic organisms. In the United States, however, it quickly crowds out all other species, growing in thick mats that make recreational use of the infested pond impossible, and often impeding water movement to the point that it can cause flooding in infested areas. A common aquarium and water garden plant, hydrilla was first released in Florida, and now infests 43 percent of the public lakes and ponds in that state. Hydrilla spreads rapidly and costs the state of Florida about $44 MILLION each year just to manage. With the recent addition of Massachusetts, hydrilla has now spread to 18 states across the country.

Photo by Allson Fox

While no one is absolutely certain how hydrilla made it to Long Pond, the discoverers of the Perfect Weed suspect that it escaped from a water garden on the grounds of an area home. Though a less likely scenario, the hydrilla may also have been introduced by a boater who had recently visited an infested lake or pond in another state. After its discovery, all boat ramps accessing the pond were closed to prevent the spread of the plant to other water bodies in the area. The town of Barnstable also had to close the pond for several weeks in order to apply a herbicide treatment (which cost around $60,000 in the first year). Needless to say, lots of folks were very unhappy - especially since this occurred in the height of the recreation season.

Clearly, the introduction of hydrilla and the resulting impairment of Long Pond was not an intentional act. However, by exercising a few cautions, you can help our state to be spared the negative impacts of many encroaching invaders.



Adapted from "Biological Invaders: Threats from Aquatic Invasive Species and What You Can Do to Keep Them Out of Our Waters," written for Coastlines by Jay Baker.