|Coral reefs are one of the most complex and colorful
tropical ecosystems. Coral reef organisms build massive and intricate
physical structures that are home to some of the most fascinating plants
and animals in the world. Although coral is often mistaken for a rock or
a plant, it is actually composed of tiny, fragile animals called coral
polyps. When we say "coral" we are actually referring to these animals
and the skeletons they leave behind after they die. The group includes
the important reef builders known as hermatypic corals, found in
tropical oceans. The colony of polyps functions essentially as a single
organism by sharing nutrients via a well developed gastrovascular
network, and the polyps are clones, each having the same genetic
structure. Each polyp generation grows on the skeletal remains of
previous generations, forming a structure that has a shape
characteristic of the species, but subject to environmental influences.
Most reefs are located between the tropics of Cancer and Capricorn, in
places such as the Pacific Ocean, the Indian Ocean, the Caribbean, the
Red Sea and the Arabian Gulf.
The largest and most famous coral reef in the world is the Great Barrier
Reef, located off the coast of Queensland, Australia. One of the seven
wonders of the natural world, it stretches for over 2,300 km, and is a
result of the build up of coral organisms over millions of years. It is
a truly amazing part of the world, and hugely diverse in the life forms
it supports – from algae to fish, from birds to reptiles, and even
mammals like dolphins, it supports a whole host of living things.
Interesting fact: the Great Barrier Reef is larger than the Great
Wall of China and is the only living thing on earth that can be seen
Tragically, coral reefs like the Great Barrier Reef are under threat.
Climate change has led to coral bleaching (loss of essential symbiotic
algae which can cause coral death) due to rising ocean temperatures.
Mass bleaching creates detrimental knock-on effects for coral
communities – for example, the fish that feed on or around the coral.
|Pollution is also causing a decline in coral reefs, due
to poorer water quality. Chemicals used in farming that make their way
into the sea are damaging. Shockingly, mining companies have been known
to empty vast amounts of waste water into coral reefs and this can have
serious effects on a reef population.
Similarly, shipping accidents – particularly oil spills – impact
negatively on the delicate balance of life in coral reefs. There are so
many species interacting at such mutual levels that any slight change in
external environment can tip this balance and create problems for the
reef. Human impact – industrialization in general – has over the years
destroyed large parts of coral reefs. The Great Barrier Reef, it was
found in a 2012 study, has lost over half its coral cover since 1985.
Other human activity, overfishing, for example, has led to a decline in
certain fish populations and disrupted the food chain. Nowadays, over
one third of the Great Barrier Reef is protected by law against removal
of any species, but some say that is not enough. Thankfully activities
like oil drilling are prohibited in the area.
Tourism, too, is considered damaging to this great reef: over two
million people visit it annually. While tourism is largely managed with
a view to being ecologically sustainable, there remain concerns about
the large volume of visitors. However, tourism is economically important
for the area.
What we must not forget is that the Great Barrier Reef is an important
feature in the culture of the aboriginal people who have lived in the
area for 40,000 years. In addition, coral reefs throughout the world are
incredibly rich areas of life, and their ecosystems have far-reaching
effects throughout the world. For these reasons, they should be
protected at all costs.