From UPSC perspective, the following things are important :
Prelims level : Biorock Technique, Coral Bleaching
Mains level : Coral restoration measures
The Zoological Survey of India (ZSI), with help from Gujarat’s forest department, is attempting for the first time a process to restore coral reefs using biorock or mineral accretion technology.
What is Biorock Technique?
- Biorock is the name given to the substance formed by electro accumulation of minerals dissolved in seawater on steel structures that are lowered onto the sea bed and are connected to a power source, in this case solar panels that float on the surface.
- The technology works by passing a small amount of electrical current through electrodes in the water.
- When a positively charged anode and negatively charged cathode are placed on the sea floor, with an electric current flowing between them, calcium ions combine with carbonate ions and adhere to the structure (cathode).
- This results in calcium carbonate formation. Coral larvae adhere to the CaCO3 and grow quickly.
- Fragments of broken corals are also tied to the biorock structure, where they are able to grow at least four to six times faster than their actual growth as they need not spend their energy in building their own calcium carbonate skeletons.
Significance of the move
- The technology helps corals, including the highly sensitive branching corals, to counter the threats posed by global warming.
- In 2015, the same group of ZSI scientists had successfully restored branching coral species (staghorn corals) belonging to the family Acroporidae (Acropora formosa, Acropora humilis, Montipora digitata) that had gone extinct about 10,000 years ago to the Gulf of Kachchh.
- The stunning colours in corals come from a marine algae called zooxanthellae, which live inside their tissues.
- This algae provides the corals with an easy food supply thanks to photosynthesis, which gives the corals energy, allowing them to grow and reproduce.
- When corals get stressed, from things such as heat or pollution, they react by expelling this algae, leaving a ghostly, transparent skeleton behind.
- This is known as ‘coral bleaching’. Some corals can feed themselves, but without the zooxanthellae most corals starve.