Answer:
Intertidal zone
Step-by-step explanation:
The intertidal zone is the area which in low tide is above the water and at high tide below the water.
The area lying beyond the continental shelf is called the open-ocean zone.
The area lying just above the continental shelf is called the neritic zone.
An estuary is a coastal body which is located at the point where rivers merges with the ocean.
Hence, the intertidal zone is being discussed in the question.