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The shallow,
warm, crystal clear waters surrounding the Cayman Islands have provided
us with some of nature's most spectacular marine
life, none more noteworthy than our breathtaking coral reefs. For hundreds
of years, Caymanians depended on healthy coral reefs to provide food,
building materials, medicines and even decorative objects. To this day,
our coral reefs are integral to our island economy thanks to their contribution
to tourism and fisheries. In addition, they play a critical role in protecting
the shore from storms and hurricanes.
Although sometimes viewed as a separate entity, coral reefs are a vital
part of a vast inter-connected marine ecosystem that also includes seagrass
beds and mangrove wetlands. Each system depends heavily on the others,
resulting in a tightly integrated and finely balanced marine environment.
Changes in one area of a system may have 'knock on' effects
through all of the other systems. It is hard to imagine the massive reef
structures and reef walls as fragile, living entities, but coral reefs
are extremely sensitive to external pressures and over-exploitation.
The mucus, or 'skin', that forms a layer over corals can
be damaged simply by the touch of a hand or contact with a snorkeller's
fin. Once damaged, the living layer of tissue is exposed to bacteria,
which can prove fatal to coral.
Coral reef structures are actually built from the skeletons of tiny creatures
living in colonies. A closer look at the colourful colonies will reveal
thousands of tiny bumps, called polyps. Each of these polyps is an individual
coral animal, all of which join together to form a coral colony. Most
coral colonies start life as a single polyp, no bigger than a pinhead,
that drifts with the ocean currents to settle on a suitable surface,
such as a bare rock bottom. Once settled, the newly established coral
polyp begins to grow, laying down a skeleton by extracting calcium
carbonate from the surrounding water and budding off a new, individual
polyp identical
to itself. Continued budding is the mechanism for increasing the size
of the colony but not, in general, producing new colonies. As this
process repeats itself, time and time again, over many thousands of
years, so
the tremendous reef formations that can be found in Cayman, have been
formed.
As well as budding, coral can reproduce sexually. This results in the
formation of a free-floating larva, which, when settled, starts developing
as a new colony. In the Caribbean, the main spawning period is long,
lasting from July through September. During this period, corals release
sperm and eggs at night using the moon as their cue to ensure they
spawn together. Fortunate night divers can sometimes witness the milky
white
releases.
Corals feed at night by stretching out their tentacles
to capture tiny animals suspended in the water column. Coral tentacles
contain specialised
cells called nematocysts, which act like poison darts to paralyse
the prey which is then passed to the coral's central mouth. During
the day, they withdraw their tentacles into a cup-like skeleton and
are fed by algae (single cell plants) residing within their tissue.
The algae
use sunlight along with the coral waste products to make food for
themselves and the corals. The corals, in turn, give the algae nutrients
they
need to survive and provide a home. This type of mutually beneficial
relationship
is called symbiosis. This relationship is especially important for
coral growth around the Cayman Islands as tropical waters are typically
nutrient
poor and food for corals is scarce. Without the algae, corals would
not survive. Interestingly, it is the algae that are responsible
for giving
each coral its beautiful colours.
In addition to hard corals, horny
corals (sometimes called soft corals) can also be found on Cayman's
coral reefs. Sea fans or gorgonians
do not produce a hard skeleton. Instead, their skeletons are formed
within their bodies as a horny substance. The skeletons of these
corals are
flexible so that their branches wave back and forth in the currents.
Anyone visiting the reef will quickly notice that corals are not
the only inhabitants; indeed, the diversity of life on Cayman's
reefs is outstanding. Wherever one looks, there is always something
different
to see; every available nook and cranny is occupied by different
kinds
of animals, and it is this closeness of community that makes reef
systems so remarkable. Everything on a reef has a function, and
no matter how
small, that function will be vital to other creatures, making the
whole system an extremely well balanced and tightly integrated
living unit.
Coral reefs provide Cayman with immeasurable benefits ranging from
the rich and diverse resources that can be harvested, to our safe-harbours,
tranquil lagoons and the sand which makes up our idyllic beaches.
In more recent times, Cayman's coral reefs and marine environment
have helped attract a multitude of visitors from around the world
who
have come to enjoy the natural beauty and majesty of our underwater
realm.
In 1996, the Cayman Islands' Department of Environment began a
long term reef monitoring programme encompassing all three islands.
The study is designed to assess and monitor the living coral cover
of our
reefs and document any changes over time. This information can
then be used to guide management decisions. Additionally, the Marine
Conservation
Laws act to protect our reefs and allow for the establishment of
our Marine Parks. No marine life may be taken on scuba or removed
by excavation
without prior written approval of the Governor-in-Council. Furthermore,
no vessel is allowed to anchor in coral. It is hoped that with
these laws and a new awareness of the importance of our coral reefs,
Cayman's
marine environment will be preserved for future generations of
the Cayman
Islands.
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