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Reefs of New Caledonia. There are 350 varieties of coral and 2700 species of fish. Polynesian lagoons.  As in New Caledonia, there would also be 350 species of coral reefs. 
Great Barrier Reef of Australia :  there are 500 varieties of corals). A reef of that size is also a space of great biodiversity, an ecosystem that sustains itself.  The disappearance of coral founders would have serious consequences, including the planned destruction of protective reef limestone, opening the ocean on the coasts of the island.


The corals take various shapes : staged plates, horn bushes, branches, balls, convolutions (brains).



       


The madreporia are frailty especially when they are shaped like branches, horn bushes and plate (foliaceous).


..


The madreporia "brain" above on the right, built solid rounded masses much more resistant than the other forms.

Softcorail (photo CNRS)

 Coral specie was there 500 millions years ago, but they would be now in danger (see destruction map : in french, très dégradé means poor state, very attacked) :

- Tourism : because of tourism, the Indian Ocean would be the most spoiled, then Carribean (Cuba excepted !), but Polynesia  regresses too. 

New Caledonia is not too much spoiled, because tourism is lower there.

- Rise in the sea level : risk limited During one 11000 years period, the rise of water caused by the ice thawing was compensated by the madreporia at a rate of three centimetres a year (that is to say 300 meters). At the contrary the central cone of the volcano disappeared when it was not too high (case of the atolls). Within a much more longer period, it is the sinking of the bas of the sea which intervenes (hundreds of millionsyears).

- Increase of sea temperature : it would be currently the major risk with the following one.
However, an Australian team suggests that the rise in the temperature of water would not be only in charge. Indeed, the absorption of CO2 by water (carbon dioxide), would increase its acidity which would cause a drop in in its turn the dissolved carbonate rate. From where a deficiency for the constitution of their calcareous skeleton.

Another idea is that if corals could dead were they live now, they could migrate or spread in new areas getting more hot.

- Pollution (accentuated by tourism), alteration works, (ports, hotels) landing, accommodations...

- the predatory(starfish acanthaster).

 Growing the coral artificially : tests are in action nearly everywhere in the world.

The corals are coelentérés, junction of the cnidaires which include the jellyfishes, the madreporia, the gorgones, the hydras.


Red gorgon (some others are yellow). The skeleton of the gorgons is not calcareous but horn (flexible and resistant).

Height tentacles for the true coral. Click to count the tentacles of the red coral.
Six tentacles or a multiple (6 times X) for the madreporia.

Large madreporia (magnus) enlarged 5 times.
Should you decide to count the tentacles, be cool..


True coral has a skeleton much harder than this of madreporia.

To simplify, one gathers all of them under the umbrella name  of "Corals".

Corals are jellyfishes upside down, fixed by their back. But they have a very small size and a calcareous skeleton which protects them >and get them so attractive by their colours (jewellery) or their reef (without them, no beautiful lagoons !).

Sea-anenomes (Actinia) are animals. kinds of tumble of tentacles being agitated with the water movements, they belong to the same family as the corals - madreporia. Below, sea anemones.

      

One the third of the corals-madreporia lay their eggs once the year in the same extremely short time; the sea becomes milky

The great night of the corals : the mystery is still total.

Nothing explains yet this incredible synchronization which is known only recently, because it is necessary to be there on this very time, wich seems to set at the full moon.



Birth of the coral : in a quarter of hour, the sea become milky.

This one is releasing a big white very thick cloud which is rising in the water (on the left of the picture, going out from a round "mouth", underneath.

  One-third of the corals-madreporia lay their eggs once a year at the same time. click to see them pop up


 Coral 3  (dead reefs, red coral, black -harvest- yellow coral, gold, pink, jewellery, chirurgic, research)

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