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 experience more variation in salinity due to their unique positions at the interface of freshwater and saltwater. They are influenced by factors such as tidal fluctuations, river runoff, and seasonal changes in rainfall, which can alter the balance of saline and freshwater inputs. Additionally, evaporation rates can concentrate salts during dry periods. This dynamic environment creates a patchwork of salinity levels, contrasting with the more stable conditions typically found in open ocean and deep-sea habitats.