Science / Tides and Currents / Estuary: An embayment of the coast in which fresh river water entering at its head mixes with the relatively saline ocean water. When tidal action is the dominant mixing agent it is usually termed a tidal estuary. Also, the lower reaches and mouth of a river emptying directly into the sea where tidal mixing takes place. The latter is sometimes called a river estuary.
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Science / Marine Biology / Seasonal Estuary: An estuary in which salinity at any one geographic point changes seasonally (e.g., decreases during the spring melt) MORE
Science / Marine Biology / Vertically Homogeneous Estuary: An estuary in which, at any given location, wind or tidal mixing homogenizes salinity throughout the water column MORE