The importance of mangroves

Mangroves are a vital part of the Cayman Islands’ ecosystem, but one that is under more pressure than any other. From the impact of environmental changes to development pressure, the position of mangroves at the intersection of land and sea means that this ecosystem is vulnerable to pressures from both sides.

“Mangroves are one of the major habitat types found in Grand Cayman – something like two thirds of our landmass used to be mangroves. The interior mangrove wetlands are still very extensive, with about 8,500 acres still almost entirely in its natural state,” said Paul Watler, environmental programmes director at the National Trust for the Cayman Islands.

However, it is the mangroves along the coastline that have suffered most, especially from development pressure.

Yet mangroves in the Cayman Islands have virtually no protection under the law, according to Gina Ebanks-Petrie, director of the Department of Environment.

“The Development Plan depicts a Mangrove Buffer Zone on some areas of mangrove fringing the North Sound. The Development and Planning Regulations stipulate that development should only be allowed in a Mangrove Buffer Zone in “exceptional circumstances” but allows the Central Planning Authority to determine what these exceptional circumstances might be,” she said.

Ms Ebanks-Petrie said the “arbitrary and ineffective application of what might otherwise have been a useful piece of legislative protection for mangroves” has meant that little protection is in fact granted to the mangroves.

Mangroves are under serious threat globally from rising sea levels and increased storm intensity due to climate change. With these factors at least to some extent out of our control, at least in the short term, it is vital to protect mangroves from human impact wherever possible in order to minimise the additional stress this can place on a very scarce and valuable resource.

Mangroves offer some of the highest carbon sequestration levels per hectare of any ecosystem, making it a good defence against climate change. Although few realise it, the central mangrove wetlands in Grand Cayman have a significant impact on the rainfall patterns on the Island.

“Ecologically speaking since the prevailing winds in our part of the Caribbean tend to come from the east and go the west, due to evapotranspiration from the mangroves there tends to be a lot more rainfall on the western side of the country,” Mr. Watler said.

The mangroves also play an important role in the replenishment of the freshwater lens, which is very important especially due to the location of good agricultural land around the central mangrove wetland.
“Mangroves help with water retention and building up the fresh water lens. When you damage a lot of the mangroves you run the risk of spoiling the freshwater lens in that area,” Mr. Watler said.

Mangroves are recognised as a defence against the effect of storms, but in order to be effective, an extensive mangrove buffer is required, as leaving a mere hedge of mangroves at the water’s edge will not offer much protection at all.

“When we have narrow strips of mangrove around the coast designated as ‘buffer’ this is really in name only. For mangrove buffers to offer protection from storms they have to be of sufficient size,” Ms Ebanks-Petrie said.

It is well known that mangroves serve as nurseries for many species of reef fish, as the juveniles are protected from larger predators among the roots of the mangroves. Many important reef species rely on the mangroves as nurseries, while heathy mangroves also help contribute to the health of sea grass beds and the health of commercially important species like conch, spiny lobster and turtles.

Cayman suffered extensive mangrove losses due to Hurricane Ivan in 2004 and although there has been recovery in some areas, those areas that suffered the greatest losses have struggled to recover, especially as along much of the coast the mangroves on the ocean side have been cut off from the flow of nutrients by the building of roads over the years. This makes it difficult for mangroves to reestablish in areas such as South Sound.

“They are adapted to a certain set of conditions, if you take those conditions away, they are not going to live there anymore,” said Mr. Watler.

At present, mangroves enjoy limited protection, with some 1,500 acres in the central mangrove wetland under protection. The National Trust owns about 800 acres of mangroves that it holds in trust for the people of the Cayman Islands.

“Mangroves are a public service, they are a natural resource. I would really like to see a National Conservation Law come into effect, because then at least people will be accountable to somebody,” Mr. Watler said.

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  1. Mr. Watler has studied well on the importance of the mangroves.

    There is no denying their positive impact on any coastal lands worldwide, let alone Cayman.

    Many countries have recognized the benefits of maintaining and replenishing their mangrove barriers, in addition to preserving near coastal vegetation such as dense ‘walls’ of surge protecting/deflecting seagrapes; others refused and have suffered the consequences and for some reason are no wiser for it.

    Mr. Watler, I hope you have a 2nd, 3rd, 4th, and 5th……..etc talk with the Central Planning Authority if you haven’t done so already (which you probably have had).

    Your overall situation is similar to a quotation told to me by a friend many years ago.

    It had something to do about ‘casting pearls before swine’.