Final answer:
A ballast tank is a compartment on ships that holds water for stability, which can contain organisms that may become invasive species when released into non-native ecosystems. These species can disrupt local ecology and cause economic damage, leading to regulations to manage and control ballast water discharge.
Step-by-step explanation:
What is a Ballast Tank?
A ballast tank is a compartment within a ship that holds water to provide stability to the vessel. When a ship is empty or carrying a light load, these tanks are filled with water to add weight and improve the ship's stability. Conversely, when the ship is carrying a heavy load, the water is discharged to avoid excess weight.
Relation to Invasive Species
Ballast tanks are closely related to the issue of invasive species because the water taken into these tanks at the port of origin often contains a variety of living organisms. These organisms can include plant parts, microorganisms, eggs, larvae, or adult aquatic animals. When the ballast water is discharged at the ship's destination, these organisms are released into a new environment. This can lead to the introduction and establishment of non-indigenous species (NIS) in ecosystems where they are not normally found.
Examples of invasive species that have been spread this way include the zebra mussel in the Great Lakes and the European green crab along the US West Coast. The presence of these species can disrupt local ecosystems, lead to the decline of native species, and generate substantial economic costs due to impacts on infrastructure, such as water intakes, and changes to the local ecology.
To manage these risks, international and national regulations, such as the Ballast Water Management Convention, have been established to control the discharge of ballast water and reduce the spread of invasive species.