Water Release. Courtesy of L. David Smith
What is Ballast Water?
In order to maintain stability during transit along coasts
and on the open ocean, ships fill their ballast tanks with water.
Large ships often carry millions of gallons of ballast water. This
water is taken from coastal port areas and transported with the
ship to the next port of call where the water may be discharged
What are the Problems with Ballast Water?
Coastal port areas are home to a wide variety of organisms that
live in the water and bottom sediments. As a ship loads ballast
it also loads many of the organisms living in that port. These organisms
range in size and phyla, from microscopic plants and animals to
mussels, crabs, and even schools of fish!
The ballast water of shipping vessels has been a primary method
of alien species introduction throughout the world. Scientists estimate
that as many as 3,000 alien species per day are transported in ships
around the world, however, not all transported species survive the
trip and their new home. Some of the species that do survive the
trip are able to thrive in their new environment. These bioinvaders
can cause disruptions in the natural ecosystem, economic troubles,
and even carry human diseases.
What can we do about this problem?
Most of the current strategies to deal with the problems posed
by ballast water focus on minimizing transport and recommend exchanges
where ships discharge and refill their ballast tanks in the open
ocean. The United Nations International Maritime Organization and
the United States government recommend open ocean ballast water
exchange; however, very few countries have adopted this recommendation
If you are concerned about the problems with ballast water release,
contact your state and federal representatives to draw their attention
to this problem and ask them to look into measures that control
the release of exotic organisms from ballast water.
Ballast Water Fact Sheet (link)
Ballast Water Treatment
Options (PDF - 528KB)
National Ballast Survey (PDF - 128KB)
Ballast Water References (link)