Coral ReefsBy: Alica Majercinova

Geography 12

What is Coral• Corals are tiny animals, called polyps

• Each coral has a stony cup of limestone around itself as a skeleton

• As they grow, the polyps divide and form coral colonies

• These colonies build up on top of each other and form coral reefs

• These reefs are found in warm • tropical waters mostly between the Tropics of Cancer and Capricorn

Why is Coral Important• Coral reefs are considered to be one of the most beautiful,

natural habitats in the world• They are homes to large numbers of different species both

plants and animals• More species of fish are found on reefs than anywhere else in

the ocean, ranging from large sharks to tiny gobies

Why is Coral Important

• These animals provide much of the local food and new medication

• They have the second greatest diversity of species after the tropical rainforests

• Important for tourism and local economy• They provide costal protection

Types of Reefs

• Fringing or Apron reefs• Barrier reefs• Atoll reefs• Patch reefs• Ribbon reefs• Table reefs• Bank reefs

Fringing (Apron) Reefs• They lie around islands and they are attached directly to the

shore• It is separated from the shore by narrow shallow lagoons

which usually have a sandy bottom and sometimes sea grasses

• Shorter fringing reefs that are more sloped are often called apron reefs

Barrier Reefs

• They grow on the edge of continental shelves and are not attached to the shore

• It is separated from the mainland by deep and wide lagoons• These reefs are the largest in the world and include the Great

Barrier Reef in Australia, which is about 2000 km long, and the Belize Barrier Reef in the Caribbean

Atoll Reefs

• Atolls form when islands (usually the tops of underwater volcanoes) surrounded by fringing reefs sink into the sea or when sea level rises around them

• The fringing reefs keep growing and eventually form circles with lagoons inside

• Most atolls are found in the Pacific, some in the Indian Ocean and a few in the Caribbean

Patch Reefs

• They are much like barrier reefs but form small patches of coral reefs instead of one large piece

• Patch reefs are often circularly shaped and surrounded by a lagoon

Ribbon Reefs

• These reefs are fairly winding• Most ribbon reefs are thin and long

• They are usually connected to an atoll lagoon

Table Reefs• A small, isolated organic reef which has a flat top• They are future atolls but they are not yet connected to a

lagoon.

Bank Reefs

• Look like the patch reefs but they are larger• Often have a hemispherical shape

Coral Reefs are Threatened

• They are one of the world’s least protected natural habitats• Nearly 60% of the worlds's coral reefs are threatened by

human activity • ranging from coastal development, overexploration,

overfishing, and inland pollution

Causes

• Climate change and global warming• Pollution• Sedimentation

• Toxic runoff

Impacts • Coral bleaching is caused by increased water temperatures• Coral is completely dependent on zooxanthellae, which is a

microscopic algae that lives in the coral tissue and provides it with most of its nutrients

• The coral expels its microscopic algae that is responsible for its color

• The coral can’t get nutrients easily without its algae and dies

Impacts

• Sedimentation is when sediment from rivers and large amounts of erosion flow into the sea and carry the pollutants and fertilizers from the farms and factories

• This sediment covers the coral reefs and affects the coral itself and all the species

• Overuse of fertilizers adds nitrogen to the ocean and increases algae growth, which takes oxygen and blocks coral from sunlight

Impacts

• Runoff has a very dangerous impact on the reefs• The waste that runs into the oceans from industries and farms

contains toxic chemicals that can weaken and kill coral and other organisms

• An increase in chlorophyll in the water leads to a larger crown-of-thorns starfish population

• This type of starfish eats the coral and can do very much damage

Why is This a Problem

• The natural habitat is being destroyed having a large impact all over the world

• Most of the species are threatened• The local economy, costal development and tourism is at risk• The medication that is only made from coral might not be

available in the future-marine species are a major focus for new cancer research

What Can be Done?

• creating marine parks that, in turn, create new jobs • treating sewage before it reaches the reefs • well-managed marine protected areas system is one of the

most effective ways for assuring healthy reefs, while generating tourism with good business and maintaining the nearby fisheries.

I Think…

• Coral reefs are very important and it is up to us to decide if we want the coral reefs to survive

• We all need to contribute by just a little to make a big difference

The End