Q. The given graph shows the productivity of an aquatic ecosystem measured in terms of dissolved oxygen produced and consumed by green plants and photosynthetic algae where photosynthesis and respiration.
Question
What will happen during the algal bloom?

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Solution:

The excess growth of phytoplankton on water surface is called algal bloom, that mainly contain blue-green algae. These phytoplankton covers the water surface and cut off light from submerged plants due to this, there is drastic decrease in oxygen replenishment inside water. Respiration uses oxygen and hence causes decrease in dissolved oxygen. The increased growth in photosynthetic algae will lead to more photosynthesis which will increase PS+R ultimately.