Between the Mt. Pleasant, in Charleston County in South Carolina, and the string of outer barrier islands, lies a wide salt marsh.
Beaches and sand dune systems form on the side of a barrier island facing the ocean; the side facing the shore often contains marshes, tidal flats, and maritime forests.
The salt marsh here is beautiful, and here is a link to some pictures of salt marshes. I wanted to stop on the connector highway to take a picture for you, but I don’t feel safe to stop on the side of the busy connector, never mind getting out of the car.
https://stock.adobe.com/search?k=south%20carolina%20salt%20marsh
When I arrived here last December, the salt marsh was dormant. The grasses had died back and were brown. Now they are a lush and tall verdant green.
The areas between the islands and the mainland are “tidal flat” wetlands. They can be mostly mud if near where a river comes into the sea. They are “swamps” if trees and big shrubs are involved. And they are salt marshes if they open, grassy, and lined with ribbons of canals.
These salt marshes are the ecological guardians of the coast. Their grassy and sinuous channels fill and drain with saltwater as the tides ebb and flow, providing food, shelter, and nursery grounds for birds, fish, and other wildlife, ranging from dolphins and otters to snails and turtles.
Healthy salt marshes cleanse the water by filtering runoff, and help other ecosystems, including oyster reefs and seagrass beds, thrive. Conserving salt marsh helps people, too. Marshes can reduce erosion, stabilize shorelines, protect against storm surge, and support species that are crucial to recreational and commercial fishing, hunting, birding, and other activities.
The above information is in the link below, if you want to read more.
Louisa Enright's Blog 
Yes, salt marshes are crucial for all of the reasons you’ve listed. And they are absolutely beautiful in all seasons. We live in Topsfield, MA, very near Ipswich and there’s a lovely marsh between the mainland and Little Neck that juts out into the ocean. North of here is Newburyport and there are marshes there and along the way there following the coast. I love watching the grasses grow in the spring. The different shades of new green growth pushing up through the older golden and brown dry grasses from last season. We love to use salt marsh hay as mulch in our gardens too! Jan in MA