The type of ecosystem that has both salty and fresh water is called an estuary.

Here's why:

* Estuaries are areas where freshwater rivers and streams meet the salty ocean. This creates a unique environment where the two water types mix, resulting in a gradient of salinity.

* Saltwater from the ocean flows in, while freshwater from rivers and streams flows out.

* This mixing of fresh and saltwater creates a brackish water environment, which is characterized by fluctuating salinity levels.

Estuaries are incredibly diverse ecosystems, supporting a wide variety of plant and animal life adapted to these unique conditions.