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Mangrove
trees live in most of the sub-tropical and tropical countries of the world,
growing along sheltered coastlines. Mangrove
wetlands form
an important link between the land and the sea. In Cayman, three types
of mangroves typically live in wetlands: red, white and black, each of
which has evolved unique characteristics to put up with levels of salt
and a lack of oxygen that would normally kill other plants. These woody,
seed-bearing plants range in size from tall trees to small shrubs. Mangroves
fulfill many important functions for our islands: providing the basis
of the food web upon which all our marine creatures feed, acting as a
nursery for small fish and juveniles, protecting land from the effects
of storms and surges and filtering the water of sediment resulting in
the spectacular crystal-clear waters surrounding Cayman.
Mangroves have developed remarkable adaptations to enable them to survive
in, what in plant terms would be considered, a hostile environment. Black
and white mangroves make use of special roots that grow vertically above
the ground to act like snorkels. These roots allow the tree to absorb
oxygen from the air when the ground is completely awash with salt water
and the soil is low on oxygen. Black mangroves also excrete salt through
their leaves. On a dry day, it is actually possible to see the salt crystals
on the leaves. Red mangroves are the best adapted for living in salt
water and can usually be found nearest the sea, often actually growing
in the water. The roots of red mangroves give the impression of a tree
on legs or stilts; they literally allow it to 'stand' in
the water. Their means of reproduction is unlike any other: they have
large seeds called 'propagules', which look like darts, hanging
from the ends of their branches. Each propagule is a small plant with
roots already growing. When it falls from the parent tree, it can either
grow directly in the muddy sediment or float along until the root end
weighs it down, positioning it right-way-up and ready to grow.
Mangroves provide many important functions vital to
the health of Cayman's environment, including providing an ideal habitat
for birds, fish and
a wealth of different invertebrate species. Cayman's
parrots love
to nest in the hollow trunks of dead black mangrove trees. Fish make
their homes amongst the tangled roots of red mangroves, hiding from larger
fish and feeding on smaller fish and creatures that also make their homes
in the tree roots. Baby turtles and lobsters and
other juveniles thrive in the sanctuary offered by the root systems and
shallow water areas.
Invertebrates, such as the mangrove oyster, crabs, snails and shrimps,
actually make their homes on the submerged mangrove trees and roots,
making these areas a spectacularly diverse and colourful environment
for snorkeling.
In addition to the habitat they provide, mangrove wetlands also perform
numerous other essential functions. The dense and extremely strong root
systems form a perfect protection against the large waves and storm surges
that Cayman can experience during hurricanes and other storms. On a day-to-day
basis, the roots help to stabilise muddy and soft sediments that would
be stirred up by wave activity causing shoreline erosion and murky waters
devoid of marine life. They dampen the wave energy, subduing large waves
and protecting our coastlines. Mangrove wetlands act like large sponges
absorbing vast quantities of fresh water from heavy rains and releasing
it slowly and harmlessly into the marine environment. This means that
by the time rain water reaches the reef, it has been filtered by the
mangroves and the sediment stirred up by the storm has settled. Mangrove
ecosystems are also important providers of nutrients that feed into surrounding
ecosystems, thereby making them healthier and more productive.
 In the Cayman Islands, the major problem affecting mangrove
habitats is humanity's desire to convert mangrove areas into residential,
commercial and industrial developments. During the last 25 to 30 years,
rapid growth of Cayman's population and tourism industry have resulted
in a substantial amount of land development on Grand Cayman in particular.
One of the major problems is the destruction of mangrove swamps to accommodate
canal and waterfront real estate.
The implementation of Marine Parks has afforded some of Cayman's
mangroves limited protection from the onslaught of development. However,
the only current forms of protection offered to the mangroves themselves
are the designated mangrove buffer zones, National Trust ownership and
some Animal Sanctuaries. Clearly, it is time for us to critically evaluate
Cayman's priorities and give due thought to the immensely important
status of our mangroves.
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