How does ballast water affect the environment?

Large cargo ships use ballast water to balance their weight and keep them stable during a voyage. Although it is essential for the safety of the ship, ballast water can be harmful to the marine environment as its discharge can release potentially invasive species into a new marine environment.

What is ballast water and how has it contributed to the spread of invasive species in the Great Lakes?

Ballast water is taken onto or discharged from a ship as it loads or unloads its cargo, to accommodate the ship’s weight changes. Thirty percent of invasive species in the Great Lakes have been introduced through ship ballast water.

How can we prevent invasive species in ballast water?

Ship captains can help prevent many stow-away species from invading new areas simply by flushing and refilling ballast tanks with water from the open ocean before they arrive in port. In deep water far from the coast, animals flushed out of the ship’s tanks are not likely to survive.

What invasive species arrived in the US in 1988 from ballast water on ships?

Zebra mussels probably arrived in the Great Lakes in the 1980s via ballast water that was discharged by large ships from Europe. They have spread rapidly throughout the Great Lakes region and into the large rivers of the eastern Mississippi drainage.

What causes problem of invasive species in ships ballast water?

The problem of invasive species in ships’ ballast water is largely due to the expanded trade and traffic volume over the last few decades and, since the volumes of seaborne trade continue to increase, the problem may not yet have reached its peak yet. The effects in many areas of the world have been devastating.

Why does untreated ballast water destroy the local ecosystem?

Ballast water may be taken onboard by ships for stability and can contain thousands of aquatic or marine microbes, plants and animals, which are then carried across the globe. Untreated ballast water released at the ship’s destination could potentially introduce a new invasive marine species.

What happens to invasive species when they travel in ballast water?

The invasive species disrupt the food chain, foul beaches and damage infrastructure—costing citizens, industry and businesses at least $200 million per year. Most of these species were transported into the Great Lakes in the ballast water tanks of ocean-going ships.

How did zebra mussels get into lake Michigan?

The zebra mussel, Dreissena polymorpha, is believed to have arrived in North America as a freshwater ballast stowaway in commercial vessels from Europe sometime around 1986. The mussel was first discovered in the Great Lakes in Lake St. Clair in June 1988.

What is the estimated number of species transported by ship ballast?

It has been estimated that in the 1990s ballast water may transport over 3,000 species of animals and plants a day around the world (NRC, 1995), and there is evidence that the number of ballast-mediated introductions is steadily growing.

Why does untreated ballast water destroy the ecosystem?

What is ballast water and how can it bring about introduction of alien species into an ecosystem?

Ballast water is routinely taken on by ships for stability and structural integrity. It can contain thousands of aquatic microbes, algae and animals, which are then carried across the world’s oceans and released into ecosystems where they are not native.

Why are invasive species harmful to an ecosystem?

Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats. This can result in huge economic impacts and fundamental disruptions of coastal and Great Lakes ecosystems.