Corals

We all r familiar with the word “coral”… although some do get confused whether it is grouped under plant or animal kingdom (if u take it in scientific  sense as there are exceptions ) because….. (When I asked my sister whether she had heard about coral she told me,”yea… I know… it’s a software rite?”).

Thus for those who haven’t heard about corals here are some pictures…

Yellow scroll

Stony coral

Smooth flower coral

Sea rod

Boulder coral

Apo coral

Mushroom coral

Pillar coral

Brain coral

Well, corals were first believed to be plant but later on were grouped under animal kingdom as animal cell membranes were found in them. They are found in shallow  and clear waters in colonies .

Uses

Corals not only play an important role as the habitat for various other organisms but also have

 a great economical importance as well  i.e. for trade, jewelleries and for aquarium purpose (live corals).

Ladies tend to prefer wearing coral jewelleries as some people believe that wearing red coral gives protection and power( in astrology) , also it is used to reduce the anger …people with “vrishchika rashi - scorpio“ are adviced to wear this gemstone by astrologers (I knw this since I am a scorpion too..).

Coral sand mining is extensively done in certain countries whereas coral rock is also extensively used for building purposes. ( some fishes take up the limestone skeletal material of coral, digest  the living tissue and excrete inorganic components as silt and sand).

 Reef-building corals from shallow waters are known to contain a suite of water soluble compounds (collectively named S-320) which strongly absorb near-UV light. Compounds of this type have now been isolated from the Pacific staghor coral. (W. C. Dunlap ,et.al.)Thus these substances can be used as sunscreen agents.

 Substances such as Prostaglandins (anti cancer drugs )can be also obtained from corals .

Various studies showing corals as a source of prostaglandins are done one such example is

 “A Rare Prostaglandin from the Soft Coral  of the Indian Ocean”A. S. R. Anjaneyulu, et.al.

 There have been many studies for the use of coral calcium for bone transplants. A biomaterial derived from natural corals with surgical applications is the calcium carbonate Biocoral. This substance has been used in surgeries and proved to b successful…(Natural coral calcium carbonate as alternative substitute in bone defects of the skull -Soost F et.al).

The structure of the commonly used coral, Porites, is similar to that of cancellous bone and its initial mechanical properties resemble those of bone.( “Natural coral exoskeleton as a bone graft substitute: a review”. -Demers C,et.al.)

Some coral communities called as microatolls can be used for radioactive carbon dating .

Some of the threats to coral ecosystem could be :

Due to change in temperature or salinity (salt content of water in simple language )

Corals could be affected if the water temperature increases than the optimum required even by one or 2 degrees. Decrease in salinity could also affect.

Pollution

 Land surface  runoff carrying nutrient rich soil can enhance the growth of certain algae and their overgrowth may lead to oxygen depleted conditions  and also affect penetration of sunlight into the water. Some nutrients may be harmful. Phosphates in higher concentration may slower growth of coral skeleton whereas high nitrate levels may turn out to be toxic.

Increase in CO₂

Carbon dioxide  absorbed into the ocean from the atmosphere reduces calcification rates in reef-building. The dissolved carbon dioxide gas reacts with the water to form  carbonic acid and thus acidifies the ocean which reduces the pH of ocean surface waters. Reduction in pH can cause dissolution of carbonate ion.

Coral bleaching

Corals exhibit an endosymbiotic(give nd take relationship by staying within da organism) relationship with photosynthetic microalgae having color called as “zooxanthellae”.(zooxanthellae live inside the coral tissue).

During the daytime coral polyps utilize the products of photosynthesis given out by zooxanthellae and during the night they feed on plankton by using their tentacles. Zooxanthellae is benefited by the waste products like N, P, CO₂  which it requires to grow. During the time of higher photosynthetic rate zoozanthellae are expelled from the tissue by corals in order to maintain balance, this is known as coral bleaching but when the photosynthetic rate goes still higher and more than necessary zooxanthellae are expelled it may lead to loss of co phototsynthetic pigments and the color. If such kind of condition prevails foe long time then it may lead to death of colony.

  Global Warming, thought to be the main cause of coral bleaching, weakens corals which are then prone to diseases including black band disease,white band disease and skeletal eroding band.

Overfishing

Certain fishing methods such as cyanide fishing and dynamite fishing may cause damage to reefs.

If only one kind of fish is targeted for fishing then it alters the food chain and might encourage the growth of corallivores( coral predators).One such eg.is  crown of thorns starfish which is normally fed upon by sea snail called Giant triton but they r  overfished. And thus starfish shows excessive growth due to reduced predator pressure.