This factor determines the exuberance of the mangroves, making them shorter and with less extensive coverage than those located in humid tropical regions. Considering this scenario, the mangroves of arid areas grow possibly with the food of underground fresh water. This could be the reason why they are located at the end of the rills of rainfall drainage, where due to the topography of the area, it is possible to find underground water flow.

In this research we expect to determine that:

• A mangrove needs the contribution of underground fresh water in order to exist, and

• The reason why some mangroves of arid areas are disappearing is related to underground water flow by exhaustion of the water mantle or due to the development of coastal infrastructure (roads, for example).

Underground water contributions to the mangrove shall be determined by the presence of Radon 222 (222 Rn) and its variability related to tidal change.

1982 photo: Renato Arturo Mendoza Salgado	2002 photo: Renato Arturo Mendoza Salgado
Mangrove deterioration in Enfermería Lagoon. Is the exhaustion of fresh underground water what has favored the decline of the mangrove?