f Paria - Ins and Outs of Trinidad & Tobago 2013

Watersports
This allows biodiversity to thrive,
though the ecosystem is relatively low in
nutrients. Producers, essentially plants that
photosynthesise, form the base for any food
web and are found in abundance in coral
reefs, for example algae and seaweed. The
producers provide food for the abundant
small fish and marine life, which in turn
provide meals for the larger animals.
Humans ultimately join the food chain.
The coral itself is actually a colony of small
sedentary animals (polyps) living together,
not a single organism. They are classified in
the Phylum Cnidaria, which also includes
hydroids, anemones and jellyfish. Corals
fall into the Class Anthozoa, characterised
by organisms having a radially symmetrical
body, no distinct head, with usually with a
crown of tentacles around the mouth. They
A variety of sponges, hard and soft corals
also possess nematocysts (stinging cells)
primarily on the tentacles, used in defence
or when capturing prey. The most severe
stings occur from Fire Corals (Millepora
spp.), which are not true corals, belonging
to the Class Hydrozoa. They can deliver
an excruciating and intense burning sting
(hence the name Fire Coral) when divers
accidentally touch or graze against these
pretty but dangerous creatures.
Corals are subdivided into: Subclass
Octocorallia (soft corals) and Subclass
Zoantharia or Hexacorallia (hard corals
and black corals). Octocorallians typically
have eight tentacles on each polyp and
are usually colonial. The most popular in
this group are gorgonians, which include
sea fans, sea rods, sea plumes and sea
whips. Most gorgonians are attached to a
substrate by a single holdfast at the base
of the stem that usually branches. The
branching patterns are distinctive and can
be used to determine the species; sea rods
show dichotomous branching while sea
fans have a tightly meshed, interconnected
network of branches.
Hard corals or stony corals are the true
builders of tropical coral reefs. They are
almost entirely confined to areas of warm,
shallow water and it is their skeletons,
essentially built of limestone, which are
critical to the formation of coral reefs.
Their polyps secrete calcium carbonate
(limestone) to form hard cups called
corallites that provide protection for their
soft bodies. An individual polyp consists of
a fleshy sack topped with a ring of tentacles
around a central mouth opening. Colonial
polyps tend to be very small, averaging 1–3
mm in diameter. Usually nocturnal feeders,
a night dive is the best opportunity to see
coral polyps open, their tentacles waving
gracefully, with tips looking like they were
crowned with dewdrops.
Coral polyps, though they can capture
some tiny plankton, receive most of their
nutrients from particular algae, called
zooxanthellae, which live within their tissues
and contribute to the coral’s particular
colour. Neither can survive independently
without the other; a delicate form of
symbiosis. Zooxanthellae use sunlight and
the polyp’s waste products to manufacture
oxygen and food, providing almost all of
the polyp’s dietary requirements. Turbid or
polluted water will severely affect the level
of photosynthesis occurring in the polyps,
ultimately affecting the overall health of the
coral reef negatively.
Coral reproduction can occur sexually,
through annual broadcast spawning (eggs
and sperm are expelled at the same time
into the water to ensure fertilisation) or
asexually, through a budding process.
Spawning events usually occur at the end
of August to the first week in September
and are a great attraction for divers and
photographers. Each generation builds
upon the previous generation, and that is
how the coral reefs “grow.” The growth rate
of corals and coral reefs depends on factors
such as light intensity, water temperature,
salinity, turbidity, food availability,
competition for space and predation. Upper
limit growth of coral colonies, range only
from a few millimetres per year for large,
dome-shaped corals, to about 150 mm per
year for branching corals like the Elkhorn
(Acropora sp.).
It is good reef etiquette and imperative
then, to adopt a see-but-don’t-touch
approach while enjoying the underwater
world and to refrain from breaking off
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The Ins & Outs of Trinidad and Tobago