Why do estuaries have brackish water?
Show answer & explanation
Answer: Freshwater mixes with saltwater
Underground springs add minerals — Wrong. Springs don't create brackishness. Estuaries are brackish because river freshwater and ocean saltwater mix in varying proportions.
Algae change water chemistry — Wrong. Algae don't cause brackishness. Estuaries have brackish (partly salty) water from the mixing of fresh river water and salty ocean water.
Freshwater mixes with saltwater ✓ — Correct! Estuaries are where rivers meet the ocean. Freshwater flows downstream while saltwater pushes inland with tides. The mixing creates brackish water—partially salty. Salinity varies with tides, season, and river flow. Unique species adapted to changing salinity thrive in estuaries!