Ballast Water and the Transport of Harmful Algae

Commercial ships transport oil, iron ore, grain, and other cargo to ports worldwide. Most of these ships have large steel tanks, called ballast tanks, located along the sides and bottoms of their hulls. The ballast tanks contain seawater, or ballast water, which is pumped into or discharged from the ship during cargo transfer, usually in harbors and nearshore waters.

When cargo is unloaded from a ship, the weight of the ship decreases, so seawater from the surrounding waters is pumped into the ballast tanks to compensate for the decreased weight. When cargo is loaded onto a ship, the weight of the ship increases, so ballast water from the ballast tanks is discharged into the surrounding waters to offset the increased weight of the cargo. Modern ships depend on this exchange of seawater to regulate the ship’s stability and operate safely.

The water pumped into a ship’s ballast tanks may contain numerous aquatic organisms, including viruses, bacteria, algae, jellyfish, crabs, mollusks, and fish. If the organisms within a ship’s ballast tanks survive the trip to the next destination, they may be released with the ballast water into waters in which they do not naturally occur. If these nonnative organisms survive and spread throughout their new environment, they may become invasive species. In this way, ballast water can accidentally introduce harmful microalgae and other organisms into the environment.

Related Articles

Ballast Water Monitoring

Ballast Water and the Transport of Harmful Algae

Commercial ships transport oil, iron ore, grain, and other cargo to ports worldwide. Most of these ships have large steel tanks, called ballast tanks, located along the sides and bottoms of their hulls. The ballast tanks contain seawater, or ballast water, which is pumped into or discharged from the ship during cargo transfer, usually in harbors and nearshore waters.

Read More »
Ballast Water Monitoring

Ballast water

Ballast loading is necessary to stabilize ships at sea. To this end, water is collected in special ballast tanks before departure from the port. This reduces the load on the hull, provides lateral stability, improves propulsion and maneuverability and compensates for weight changes at different load levels and due to fuel and water consumption. Large tankers can carry in excess of 200,000 m3 of ballast water. When pumping up ballast water, local marine organisms will inevitably also be included and probably also some sediment with adsorbed marine organisms.

Read More »
Potable Water

POTABLE WATER

Potable water, also known as drinking water, comes from surface and ground sources and is treated to levels that that meet state and federal standards for consumption.

Read More »
Potable Water

Drinking Water Standards and Regulations

The U. S. Environmental Protection Agency (EPA) sets standards and regulations for many different contaminants in public drinking water, including disease-causing germs and chemicals. Read the information below to learn more about EPA’s drinking water regulations.

Read More »
Potable Water

Water, Hydration and Health

This review attempts to provide some sense of our current knowledge of water including overall patterns of intake and some factors linked with intake, the complex mechanisms behind water homeostasis, the effects of variation in water intake on health and energy intake, weight, and human performance and functioning.

Read More »