Estuaries, where fresh water from rivers mixes with salt water from the oceans, are among the most productive environments on Earth.
(fresh water from rivers; mixes; with salt water from the oceans) (Estuaries, where fresh water from rivers mixes with salt water from the oceans; are; among the most productive environments on Earth)
fresh water from rivers Estuaries, where fresh water from rivers mixes with salt water from the oceans
mixes are
with salt water from the oceans
among the most productive environments on Earth