What is an estuary and why is it more diverse

Estuaries are areas of water and shoreline where rivers meet the ocean or another large body of water, such as one of the Great Lakes.

Many different types of plant and animal communities call estuaries home because their waters are typically brackish — a mixture of fresh water draining from the land and salty seawater. This unique combination of salty and fresh water creates a variety of habitats

answer; i believe the correct answer is ; large pieces of pangaea drifted in different directions over millions of years;