Ballast Water

In order to remain stable when loading and unloading cargo, filling up or burning fuel, ships may take on and release ballast water.  Cruise ships, large tankers, and bulk cargo carriers use a huge amount of ballast water, which is often taken on in the coastal waters in one region after ships discharge wastewater or unload cargo, and discharged at the next port of call, wherever more cargo is loaded. Once ballast water is taken on board, it may be released half-way around the world.

Ballast Water Discharge

 

Ballast water discharge typically contains a variety of biological materials, including plants, animals, viruses, and bacteria. These materials often include non-native, nuisance, exotic species that can cause extensive ecological and economic damage to aquatic ecosystems. If the organisms survive, they can cause major ecological and economic damage to the ecosystem.  (MIT, Wiki)