Science needs your help in controlling alien organisms that may be setting up camp on your boat’s hull.

By Elizabeth Ginns Britten — July 2005

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Did you know that hundreds of different marine plants and animals have invaded bays and harbors on the East Coast of the United States? While some become members of the local flora and fauna, others are not so benign. They’re called alien species, may look like small grapes or large prunes, and range in color from gray to brown to bright orange. Most important, these aliens can displace native species and degrade habitats, creating a profound impact on biodiversity. They can also cause thousands of dollars’ worth of damage to marinas, industrial facilities, and aquaculture sites. These invaders reproduce quickly, can thrive in an array of different coastal habitats, and will survive long journeys and severe conditions. Distance is not a factor.

Historically shipping has been the principle means of the movement for these pests; therefore commercial tankers and container ships have garnered most of the attention associated with the problem. More recently, however, studies indicate that smaller, privately owned vessels are also an important factor. Specifically, pleasurecrafts, which are regularly transporting species from port to port, rapidly increasing the size of affected areas. And if these fouling beasts attach themselves to your hull, they can cost you money by increasing hydrodynamic drag, which reduces fuel efficiency, and wreak havoc with previously untouched environments. Since traditional pest-removal methods like spraying don’t work in the marine environment once new populations are established, they are almost impossible to remove. Not surprising, the search is on for natural biological controls—competing animals like snails—that can keep the populations of these newcomers in check while not harming the environment.

Scientists say that control is difficult but not impossible, and fortunately you can help. Maintaining a clean hull is the most obvious and effective means of stemming the tide of invasions. This includes not just scrubbing the hull but running it into brackish or fresh water, which will kill the organisms. If you trailer your boat, hose down the hull with fresh water whenever possible. Also keep a close eye on your rudder, hull, and bow thruster; these animals are tiny and can work their way into the smallest cracks, and it only takes a few to establish a new colony.

Scientists are currently studying the role of recreational yachts in transporting some of these alien species. The success of this project depends upon volunteers, so they are looking for boaters who winter in the Fort Lauderdale, Florida, area and make trips northward along the Eastern seaboard, since these organisms typically do well in warmer waters and head north for summer. If you volunteer, a certified scuba diver will survey your hull and take underwater photographs of it. If you’d like to participate in this worthwhile study, click here to download a printable form or e-mail Dr. Robert Whitlatch at

This article originally appeared in the June 2005 issue of Power & Motoryacht magazine.

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