Explain why estuaries salt marshes and mangrove forests have more variation in salinity than other marine habitats like the ocean and sea floor

Estuaries, salt marshes and mangrove forests have more variation in salinity than other marine habitats like the ocean and sea floor because of the environment present in these locations. They are considered to be unique ecosystems in semi-sheltered areas near the ocean coastline. These areas often serve as nursing grounds where young marine life is protected during development.