Grand Cayman's Central Mangrove Wetland is the ecological heart of Grand Cayman. It is critical to so many important natural processes that the National Trust for the Cayman Islands considers its long term protection to be one of the fundamental requirements for the well-being of future generations in the Cayman Islands.

Approximately 1,500 acres of the Central Mangrove Wetland is protected through the Marine Parks Law, forming part of the Environmental Zone which has been in effect for Little Sound and its fringing mangroves since 1986. Efforts are now underway to increase the area of the Wetland under protection, through conservation land purchase.  The Trust has, to date,  purchased 765 acres as part of its Central Mangrove Wetland Reserve. 

The Central Mangrove Wetland is part of a large scale water flow system, filtering and conditioning the surface water and shallow ground water which flows into North Sound. Both by constant tidal flushing of the mangrove fringes, and by occasional massive overflows of accumulated rainwater from the entire Central Mangrove basin, the Wetland provides a flow of nutrients into North Sound.

These nutrients form the base of a complex food chain from the Turtle Grass and shrimp mounds in Little Sound, through to the snappers and lobsters which move from the mangroves to the reef. The entire living system of North Sound is inextricably linked to the Central Mangroves, and would collapse if the Wetland were ever destroyed.

The Wetland covers a total of about 8,500 acres, still almost entirely in its natural state. Except for areas of open water, it is covered by a canopy of trees, which absorb sunlight and radiate part of that energy as heat, warming the air near the leaves. The same air also becomes saturated with water vapour, evaporating from the leaves' breathing pores and from the ponds below. Warm air is less dense than cooler air, and rises in a complex pattern of convection currents. Saturated air rising above the Central Mangrove Wetland in this way forms rapidly developing clouds, which are carried west by the prevailing winds and dump rain over the central and western districts of Grand Cayman.

This process is believed to contribute a large part of western Grand Cayman's rainfall, which is 40% greater than in the eastern districts. Without the Central Mangroves, George Town and West Bay could be almost as dry as East End, but without the benefit of an unspoiled ground water lens to keep the trees healthy and the well water fresh.

The Central Mangrove Wetland is surrounded by some of Grand Cayman's best agricultural land, and also by a system of fresh water lenses. The Wetland helps to hold back rainwater flowing towards the sea from higher land, and so maintains the fresh water lenses and holds up high fresh water tables in agricultural land. Mangrove canalization and development in western Grand Cayman has already shown how vulnerable our agriculture and groundwater supplies are to the destruction of neighbouring wetlands.

West Indian Whistling Duck, Grand Cayman Parrots, Snowy Egrets and many other native birds depend on the Central Mangrove Wetland for food, shelter and as a place to breed. Various crab species, smaller crustaceans - some of which have only recently been described by scientists - and countless species of insects and other invertebrates inhabit the Wetland, along with fish, Hickatees, Agouti and many other animal life forms. The Red, Black and White Mangroves are joined by Buttonwoods, and a variety of dry land trees like Mahogany and Wild Fig have also gained a foothold in the more remote areas of the Wetland, where fresh rainwater sometimes floats on top of the salty groundwater.

All of Cayman's mangrove wetlands have developed in their present form since the last Ice Age, which has been a period of significant sea level rise. Sea level in the Caribbean is still rising, currently at a rate of about 1 foot every 100 years. As rising sea level gradually submerges mangrove wetlands, the dead wood and leaf litter on the wetland floor is cut off from the air, and its decomposition is slowed. This process leads to the formation of peat, which builds up on the wetland floor to keep pace with rising sea levels. Over thousands of years, thick layers of mangrove peat have been deposited in areas where the underlying rock is now far below sea level.

The Central Mangrove Wetland is laying down about three million cubic feet of salt-saturated mangrove peat every year in this way. The peat is very rich in carbon, originally collected as carbon dioxide gas absorbed from the atmosphere by the mangroves (all plants absorb carbon dioxide, releasing oxygen as they grow). So the way in which mangrove wetlands develop during periods of rising sea level actually removes carbon dioxide gas from the atmosphere. Carbon dioxide is released to the atmosphere by processes like burning oil, gas and forests, and under human influences it has been building up in the world's atmosphere to the point that it is causing global warming, leading to climate disruptions. Our wetlands are doing Cayman's small part in combating this problem, at least partially offsetting our fast increasing carbon dioxide emissions from vehicles, electricity generation and deforestation.

Few of us have ever struggled deep into the Central Mangrove Wetland: access is extremely difficult! We should all be aware, however, that it is there in its natural state, quietly providing a range of environmental services which are tremendously valuable to us now, and will be equally valuable to future generations.

Last Updated: 27 Jun 2012