The salt in seawater is what most obviously distinguishes it from freshwater, and affects the ecology of coastal lagoons, tidal flats, and river mouths.
(The salt in seawater; affects; the ecology of coastal lagoons, tidal flats, and river mouths) (The salt in seawater; is; what most obviously distinguishes it from freshwater)
The salt in seawater The salt in seawater
affects is
the ecology of coastal lagoons, tidal flats, and river mouths
what most obviously distinguishes it from freshwater