salt marshes typically sit above the high tide mark.

This is false. They are not located above the high tide mark but rather in the intertidal area, which is the area between the land and the salt water and is constantly covered by tides. When the tides retreat, they leave the salt on the ground so salt water marshes are created in these areas, and they get tide flooded over and over again.

Iwould say all the above personally but i think the desert would be d