Why is there less oxygen at the surface level than in the depths of the ocean? a. oxygen is very light and rises to the top b. a lot of sea life consumes oxygen at the surface level c. nitrogen breaks down the oxygen at high temperatures d. oxygen is absorbed at the surface level but cannot remain there

Dissolved oxygen is also put into the water as a byproduct of phytoplankton photosynthesis. The oxygen found in the deeper water comes from mixing with surface water. Photosynthesis can cause the water to have more dissolved oxygen than the saturation amount. ... When this happens, the deep water can become unhealthy.

Correct B). A lot of sea life consumes oxygen at the surface level

The surface water has less oxygen concentration, which is close to equilibrium with the atmosphere. The colder water is known to hold more oxygen as compared to warmer water.

Thus, the deep ocean water is colder than surface water, so they hold more oxygen as compared to the surface water, which is warmer than the deep water. The surface water supports most of the water life, which consume oxygen present at the surface level.

Hence, the correct answer would be option B.