Pavona Coral is a cleractinium coral, which means it is a “hard” coral with a limestone skeleton. It is light brown or greenish-brown in color and has thin vertical leaves and twisted branches but can develop thicker leaves when grown in shallow areas with strong waves. They can grow as an isolated colony or form large colonies that can cover more than ten meters. Until very recently it was thought to be the same species as the cactus coral (Pavona decussata), but studies have shown that the Pavona decussata and the Pavona cactus are, in fact, two different species.
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- 1 Habitat
- 2 Biology
- 3 Threats
- 4 Conservation
- 1 Food
- 2 Reproduction
- 5 Sources
The Pavona cactus is an Indian-Pacific coral with a range that extends from Japan to Australia and from the Red Sea to [[Tahiti]. This coral is found in the lagoons and the upper slopes of the reefs where there is a small current as well as in the cloudy waters protected from the waves. It is often found growing amidst coral colonies of Pavona decusata cacti.
The Pavona cactus has been shown to reproduce sexually, although it also reproduces asexually. It does this by fragmentation, a form of asexual reproduction where a new organism grows from a fragment of the matrix of a fully grown mature individual. However, further work is needed on the biology of this species for which so little information is available.
Like many other corals, this species has microscopic algae (zooxanthellae) living within its tissues. Through photosynthesis, symbiotic algae produce molecules rich in energy that the coral can use as food. In return, coral provides zooxanthellae with protection and access to sunlight.
The Pavona cactus faces a number of threats including rising water temperatures due to climate change that influences coral bleaching. During coral bleaching, symbiotic algae are expelled, leaving corals weak and vulnerable to an increasing variety of harmful diseases. This is a threat that all corals face, although this species has been found to be less susceptible to bleaching effects than some other coral species. Another problem is the increasing amount of carbon dioxide in the atmosphere. Because the Pavona cactus grows through the construction of its calcified skeleton, increasing carbon dioxide in the atmosphere reduces the carbonate ions available to corals thereby limiting their growth.
Since the Pavona cactus has been confirmed as an independent species, further research on its biology will help guide future conservation actions for this species. Unfortunately, on a larger scale, it has been considered that the environmental threats caused by climate change may be too severe for most corals. At a meeting of scientists held in October of 2009 , he discussed the ambitious idea of freezing in liquid nitrogen corals in order to preserve them for reintroducing when the weather was stabilized overall.
Polyps contain symbiotic algae; Mutualists, both organisms benefit from the relationship, called zooxanthellae. The algae photosynthesize, producing oxygen and sugars, which are used by polyps, and feed on the catabolites of the coral, especially phosphorous and nitrogen . This provides them with 70 to 95% of their nutritional needs. The rest is obtained by trapping plankton and dissolved matter in the water column. In the latter case, the genus has species with enormous autotrophic capacity, that is, they have the ability to capture simple inorganic substances, such as carbon dioxide, and transform them into organic substances for their nutrition.
The colonies produce sperm and eggs that are fertilized in the water. The larvae roam the water column until they land and settle on the seabed, once there they become polyps and begin to secrete calcium carbonate crystals, specifically aragonite, to build their skeleton, or coralite. Subsequently, they reproduce asexually by budding, giving rise to other specimens, and thus forming the colony.