Coral Reef

coral reefA number of publications are available from IUCN down-loadable in pdf. I came across a  great one on coral reefs, and with Sodwana as our backyard with its collection of 14 rocky reefs I thought I would highlight some of the interesting facts.  Sodwana is one of the most southern coral reefs in the world, even more south than the Great Barrier Reef, and is host to some 1 200 species of fish, six being endemic to the Sodwana area.

Sodwana Bay National Park was established in 1950 and is a haven for divers and fishermen alike. The reefs are estimated to be in the region of 4000 years old, while the seabed forms a more ancient coastline of dunes and beaches formed around 80 000 years ago when sea levels were much lower.

Corals are two-layered invertebrates that live in groups (i.e. they are colonial) and are
related to jellyfish and sea anemones.
Corals are made up of tiny individuals called polyps. Each polyp is like a fluid-filled bag
with a ring of tentacles surrounding its mouth, and looks like a tiny anemone. Polyps within
a colony are linked by living tissues and can share their food.

In some corals, the polyp extracts calcium carbonate from the sea and secretes it as a cup
of calcium carbonate from the bottom half of its body. These cups provide anchorage
for the polyps but when threatened, the polyp can retreat into the safety of the hard cup.
When the calcium carbonate cups of many billions of these polyps fuse together, they
form coral reefs.

Corals can be divided into two main types, Stony Corals and Soft Corals.coral reef

Stony Corals are also called reef builder corals due to the secretion of calcium carbonate (limestone), their skeleton, which in time form coral reefs. It is important to note that it is crucial for the survival of corals sea temperature is between 25 to 30degC and no deeper than 60m. Anything out of this range has disastrous effects and threatens the future of all our reefs.

Soft Corals as the name indicates dont have a calcium corbonate skeleton, instead they have tiny hardened calcium particles that make up their bodies and provide support.

Coral reefs are the skeletons of stony coral polyps cemented together. Corals grow very
slowly – some grow only about 3-20mm per year. Therefore, some reefs form over several
million years.

As these corals grow and die, they leave behind their calcium carbonate skeletons.
On these skeletons, other corals grow. As the years pass, walls of coral begin to form:
massive walls of rock. As the waves and currents beat upon these reefs, nooks, crannies,
ledges and caverns form in these walls.

coral reefJust as there are many different kinds of corals, so can coral reefs be divided into three different categories. These are fringing reefs, barrier reefs and atolls.

Fringing reefs grow in shallow waters close to the coast and Sodwana could be classed in this category.

Barrier reefs grow parallel to the coastline and are separated by a lagoon that can vary in width of up to 100km from the coast. The best example of this of course is the barrier reef off Australia’s east coast that is just over 2 000kms.

Atolls usually are the result of a coral reef surrounding an island that has long since sunk or been flooded by rising oceans, forming a ring that surrounds a protected lagoon. The Maldives is made up of 26 atolls.

Coral reefs support human life and livelihoods and are important economically. Nearly
500 million people depend – directly and indirectly – on coral reefs for their livelihoods,
food and other resources.

Further, it is estimated that nearly 30 millioncoral reef
of the poorest human populations in the world depend entirely on coral reefs for their food.• A km2 of well-managed coral reef can yield an average of 15 tonnes of fi sh and other
seafood every year ( about _wwf/ what_we_do/marine/blue_planet/
• In 1985, the world export value of the marine aquarium trade was estimated at 25-40 million
USD per year. In 1996, the world export value was about 200 million USD. The annual
export of marine aquarium fi sh from Southeast Asia alone is estimated to be between
10-30 million fi sh, with a retail value of up to 750 million USD (Bruckner, 2006).

coral reefIn conclusion, while coral reefs only cover about 1% of the Earth’s surface, because of their diversity they are called the rain forests of the ocean.

25% of the worlds fish species are housed within our reefs,  as many as 750 different coral species on one reef alone, along with algae, marine worms, sponges, crustaceans, sea stars, snails and mussels and much more.

Building awareness about coral reefs, their diversity and the services they provide, helps
greatly in mitigating the threats to these fragile ecosystems.

Awareness at the community level is most effective as it can help to encourage users of coral reefs to change their
behaviour to sustainable use of these ecosystems. Awareness at national level – through
the media and conservation education – is essential to ensure that policy makers integrate
coral reef conservation into all stages of development.

It is also critical to ensure that landbased environmental issues – such as unplanned or badly planned inland development and pollution – are prevented to safeguard coastal ecosystems such as coral reefs.

Leave a Reply

Your email address will not be published.