Swampy areas found in tropical and subtropical regions where mangrove trees have adapted to growing in shallow, salty water are

Brackish waters

Explanation:

As they are more saline than freshwater, but not as compared to seawater. Result of the mixing of estuaries and aquifers, the mangrove forests are mudskippers. And are important barrier between land and sea. Caspian sea is also an example of this.