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

Answer:

Estuaries, salt marshes, and mangrove forests are influenced by both freshwater and seawater. Rivers and rain can lower salinity, while ocean tides bring in saltier water. Evaporation and seasonal changes also affect the balance, so salinity varies more than in the open ocean or on the sea floor.