The main purpose of wildlife (movement) corridors is to

I believe the main purpose of wildlife (movement) corridors is to connect two otherwise isolated populations. Wildlife corridors are links of wildlife habitat that joins tow or more larger areas of similar wildlife habitat. They are very critical for the maintenance of ecological processes such as allowing the movement of animals and the continuation of viable populations. 

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.