PBS Newshour put together a 4 minute video describing some current research by UGA professor Merryl Alber to study what happens to coastal marshes when you change them from fresh water to salt water. This is expected to happen as sea level continues to rise in the next century. You can see the video and read a story about the SaltEX project at http://www.pbs.org/newshour/updates/coastal-ecologists-construct-time-machine-sea-level-rise/. The research has some unsettling conclusions about how the coastal marshes are likely to change over time as the water becomes more brackish and salty.
Source: Trish Hartmann, Commons Wikimedia