Multiple choice

In what way does ballast water discharged by ships cause harm to marine environment?

  1. By increasing nutrient concentration

  2. By introducing invasive species

  3. By causing hypoxia

  4. By introducing mercuric compounds
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ballast water taken up at sea and released in ports, is a major source of unwanted exotic marine life. The invasive freshwater zebra mussels, native to the Black, Caspian and Azov Seas, were probably transported to the Great Lakes via ballast water from a transoceanic vessel.

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