BallastwasserDischampfangs

In English, the term is ballast water; in German, it is Ballastwasser. Ballast water is seawater carried in ballast tanks to provide stability, trim, and buoyancy for ships when cargo is not loaded. The water is typically drawn from the sea near the port of departure and discharged at the destination. While necessary for safe operation, ballast water can transport marine organisms, including plankton, larvae, and microbes, across oceans.

If discharged into a region different from where it was taken on, these organisms may establish themselves in new ecosystems, potentially displacing native species, altering habitats, and affecting fisheries and infrastructure. The ecological and economic risks have led to widespread regulatory attention.

To prevent such transfers, international and national regulations require ballast water management. Ships must have a ballast water management plan and records, and many are equipped with ballast water treatment systems. Management methods include ballast water exchange in the open ocean to replace coastal water, and ballast water treatment systems that filter and treat water using ultraviolet light, chemical disinfection, or other technologies to meet discharge standards.

The International Maritime Organization's Ballast Water Management Convention, adopted in 2004 and in force since 2017, requires ships to manage ballast water to minimize the global transfer of harmful aquatic organisms. It establishes requirements for plans, record-keeping, and the installation and operation of ballast water treatment systems to meet specified standards (commonly referred to as D-2). Enforcement is carried out by port state control and flag states; retrofitting older vessels remains a logistical and financial challenge, but global compliance continues to expand.