Coral Reefs

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Coral Reefs

• By Alica Majercinova
• Geography 12

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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

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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

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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

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Types of Reefs

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

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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

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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

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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

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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

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Ribbon Reefs

• These reefs are fairly winding
• Most ribbon reefs are thin and long
• They are usually connected to an atoll lagoon

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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.

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Bank Reefs

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

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Coral Reefs are Threatened

• They are one of the worlds 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

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Causes

• Climate change and global warming
• Pollution
• Sedimentation
• Toxic runoff

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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 cant get nutrients easily without its
  algae and dies

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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

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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

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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

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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.

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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

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The End