Ballast water discharge and the environment

These materials often include non-native, nuisance, and exotic species that can cause extensive ecological and economic damage to aquatic ecosystems and to humans as well.

[2] A recent study suggests that if no action is taken on ballast water management, species invasion can propagate to any port in the world via global shipping network with an average of two intermediate stops.

[3] Meanwhile, studies suggest that the economic cost just from introduction of pest mollusks (zebra mussels, the Asian clam, and others) to U.S. aquatic ecosystems is more than $6 billion per year.

After unloading the payload a bulk carrier cannot simply return to the starting point, but it must load ballast to get the propeller submerged below water surface.

[6] To minimize the spread of invasive species in U.S. waterways, the Environmental Protection Agency and the U.S. Coast Guard regulate the concentration of living organisms discharged in the ballast water of ships.

[10] The zebra mussel, which is native to the Caspian and Black Seas, arrived in Lake St. Clair in the ballast water of a transatlantic freighter in 1988.

[11] Studies suggest that the economic cost just from introduction of pest mollusks (zebra mussels, the Asian clam, and others) to U.S. aquatic ecosystems is more than $6 billion per year.

[14] Under the authority of the Clean Water Act, the Environmental Protection Agency (EPA) published its latest Vessel General Permit in 2013.

Via targeted ballast management on Singapore and a few other "influential" ports, cross-region species exchange to/from the Pacific region can be combinatorially reduced.