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INTRODUCTION:
Coral reefs are
universally considered to be one of the crown jewels of our beautiful
planet. Shallow marine habitats, coral reefs are defined both by a
physical structure and by the organisms found on them and are found in
all of the world's oceans, at all depths, and are shallow marine
habitats. They are defined by both a physical structure and by the
organisms called coral polyps that are found on them. These have a very
small cylindrical body, topped with a ring of tentacles which are used
to capture food from the waters around them and as the polyps die, new polyps grow on top of and
next to the dead ones, and this contributes to the gradual slow growth
of the coral reef. Other types of animals and plants, algae, sponges and
mollusks also contribute however the primary building forces are the
living coral polyps. Often referred to as the "rainforests of the sea"
because of their incredible diversity, coral reefs are home to over
4,000 species of fish, 700 species of coral species and thousands upon
thousands of other marine plants and animals.
A great number of corals
have developed the ability to live in colonies and to build up a
communal structure. Some, known as reef-building or hermatypic corals,
build a stony structure out of calcium carbonate. This type of coral
reef is almost entirely confined to warm, shallow waters, and it is
their limestone skeletons which are critical to coral reef formation.
These reef building corals do their work slowly, and some large corals
may build up their structure at a rate of just a few millimeters per
year, while the faster growing tips of branching corals may grow at
rates of 150 millimeters per year or more. Corals can only grow in warm,
well lighted waters and require a solid surface or platform on which to
grow. These factors restrict the reef building corals to the shallow
rocky waters of the tropics
Multi-functional, reefs
provide food, shelter and breeding grounds to thousands of ocean
species, protect shorelines from erosion, and provide recreational
opportunities and sources of income for millions of people who rely on
them. Although they cover less than one percent of the ocean floor, they
are home to a quarter of the known marine plant and animal species.
Twenty five percent!!! That's a lot! And this rich, precious habitat is
now being threatened on many fronts. While they are the most
spectacular of underwater environments, they are also the most fragile.
Coral reefs have evolved over millions of years to cope with natural
forces such as hurricanes, floods, ocean currents and diseases, but they
are no match for man's destructive patterns and activities. Coastal
development, over fishing, coral mining, sewage, fertilizer and chemical
pollution, sedimentation, ocean warming and the use of cyanide and
dynamite on the reefs as fishing practices are all taking a major toll,
and they all can be traced by to man's activities.
Already over eleven percent of the
world's coral reefs have been lost to human impact and it is predicted
by scientists that over the next thirty years, up to thirty more percent
could be lost if intervention does not occur. Over sixty percent of
reefs in the world are either now severely damaged and threatened. The
loss of these coral reefs around the world would be devastating -not
only would millions of people lose their only source of food and income,
we would see the extinction of many fascinating and beautiful ocean
species, as well as lose the opportunities for advances in science and
medicine. Many corals have already provided a number of medical break
throughs in HIV and cancer treatments.
GLOBAL DISTRIBUTION:
Charles Darwin is considered to be the first person to prepare a
global map of coral reefs. As a rule, coral reefs are confined to a
broad band, roughly confined to the tropics and circling most of the
planet. Unevenly distributed within this swath, large numbers of reefs
are confined to remote island locations and offshore regions far from
the mainland. Coral reefs are largely absent from the Central Atlantic
and the shores of Western Africa and are greatly restricted along the
Pacific shores of the Americas as well as the coastline of South Asia
from Pakistan to Bangladesh. There are over 280,000 square kilometers of
coral reefs worldwide, and this figure represents only 0.089 percent of
the world's oceans and less than 1.2 percent of the world's continental
shelf. The greatest majority of coral reefs are found in the region
known as the Indo-Pacific, which stretches from the Red Sea to the
Central Pacific. For more information on specific coral reefs of the
world, visit these other sections of my website devoted to coral reefs.
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