The average depth of the oceans is about 4300 meters (m). Why do most of the marine organisms live in the top 200 m of the ocean waters?
a. Marine organisms thrive in high salinity, and the water near the surface has the highest salinity.
b. Marine organisms are healthier in the coldest waters, and the water near the surface is the coldest.
c. Many marine organisms are consumers living where food is abundant, and the water near the surface
has many producers.
d. Many marine organisms better survive in water with a low pH, and the water near the surface has the lowest pH
due to high carbon dioxide levels.