
What would happen if phytoplankton of an ocean is completely destroyed for some reasons?
- The ocean as a carbon sink would be adversely affected.
- The food chains in the ocean would be adversely affected.
- The density of ocean water would drastically decrease.
Select the correct answer using the code given below:
- 1 and 2 only
- 2 only
- 3 only
- 1, 2 and 3
Explanation
Statements 1 and 2 are correct
- Phytoplankton are the primary producers in the oceans. They include: diatoms (unicellular algae), coccolithophores (unicellular, eukaryotic protists), Cyanobacteria (Bluegreen algae) — Synechococcus, Prochlorococcus, Nostoc, Spirogyra, etc., and Dinoflagellates (flagellated protists).
- Ocean as a carbon sink would be adversely affected: Phytoplankton perform photosynthesis, absorbing CO₂ from the atmosphere. Their destruction would reduce the ocean’s ability to act as a carbon sink, leading to increased atmospheric CO₂ levels.
- Food chains in the ocean would be adversely affected: Phytoplankton form the base of the marine food chain. Their disappearance would disrupt food sources for zooplankton, small fish, and ultimately larger marine predators.
Statement 3 is incorrect
- Density of ocean water would drastically decrease: The density of seawater is primarily influenced by temperature and salinity, not the presence of phytoplankton. While phytoplankton contribute organic matter, their absence would not cause a drastic change in ocean water density.

