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Coral bleaching comparison

Coral Bleaching

At a time when the human race strives justifiably to recognize diversity and equality amongst ourselves, we can learn some lessons about coexistence from looking at the most diverse of marine ecosystems – coral reefs. Like our own civil rights and liberties, coral reefs also need to be respected, maintained and protected from the effects of human impact. Unfortunately they have suffered from coral bleaching in recent years. We'll tell you why we have to try and stop this process.

What are coral reefs?

Often called the rainforests of the sea, coral reefs are known to contain about 25% of the world's fish species…. Now there is coexistence and diversity for you.


There are 3 main types of reef structures:

  1. Fringing reefs, where they project seaward directly from the shore forming a border
  2. Barrier reefs, where they also form a border but at a greater distance from the shore. They generally have lagoon conditions in between
  3. Atolls, like our own Mnemba atoll, which form when reef grow around a volcanic island. The island subsides completely below sea level while the coral continues to grow upward, forming an atoll.

The formation and growth of coral occurs when free swimming coral larvae attaches itself to submerged rocks, hard surfaces and edges of islands. The coral polyps, when suitably attached, secrete a calcium carbonate forms the skeleton that is the. This base of all coral reefs. On the one hand the skeleton a building block for other corals to grow. On the other hand, it also offers protection to the coral and marine life that reside within and around it. Coral grows best in clear, shallow warm water, they need salt water and sufficient sunlight to survive.

What causes Coral Bleaching?

Two of the main factors that are affecting coral reefs are global warming and pollution. Coral bleaching is happening at an alarming rate threatening the survival of coral ecosystems. Rising sea temperatures due to global warming is one reason why corals bleach. Bleaching happens when corals exposed to extreme stress expel algae, which is a major source of food for the coral. This leaves the coral appearing white and pale and more susceptible to disease. Contrary to belief coral may not completely die when bleached and given the right circumstances can prevail. That said once bleached due to the stress they are under the chance of survival lessens greatly.


How can we prevent it?

Now more than ever we must make a choice to reduce our impact and our added effect to these environmental issues. By reducing our emissions, pollution run-offs into our water sources, use of plastics and overfishing we can not only help revive our ailing reefs but help them grow for future generations of marine life and humans to enjoy and live off.

As well as sustaining one quarter of fish life coral reefs can benefit local communities. Through education and the right practices, responsible tourism is one way in which a community can grow and develop by looking after the coral ecosystem.

At One Ocean, we firmly believe in not only educating our staff but also our clients. We emphasize on the need to follow safe diving and snorkelling practices and standards to help protect and learn about this amazing ecosystem.


One Ocean is partnered with Carbon Tanzania where we help offset our carbon footprint. You as a guest can help by donating to this wonderful cause.

Together we can all make a change.

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