Destruction OfThe Great Barrier reef..

 The Great Barrier Reef is the world's largest coral reeef system.It is situated in Coral sea of the coast of queensland,Australia.It is composed of above 2900 reef and above 900 island.It extends over 14 degree of latitude.The area is 344400 square kilometeres.this site is recognised as the world heritage site by UNESCO in 1981.The great barrier reef is relatively young at 5 lakh years.The average depth of 35 meters in its inshore water.The average temperature of this site is 30 degree in maximum and 21 degree in minimum.In summer time the temerature can rise.
In this reef more than 1500 species of fish ,410 types of hard coral,one third of the world's soft coral,130 species of sharks,marine turtles and more than 30 species of marine animals such as vulnerable dugong are found.Different types of algae(like seaweed),sea lettuce,sea grasses,An important plants in great barrier reef is a kind of algae crustase coralline algae.

(Crustose coralline algae)

                                                          (Vulnerable dugong) 

What is coral:-.                                                       

A living structure mode of groups of organisms called polyps.symbiotic relationship with a zooxanthellae that lives in their tissue.Polyps build skeleton limestone.Photosynthesis is done by zooxanthellae which produce oxygen for the coral to breed and creates the proper conditions for the skeleton to form.

Destruction of coral reef:-

Australia pledged half a billion dollars to restore and protect the great barrier reef.the reef is a critical national asset contributing 6.4 billion dollars a year to the Australian economy.The reef probably has not faced change in SST(sea surface temperature) and acidification at such a rate.due to global warming produce green house gas polluters such as carbon dioxide,carbon monoxide,nitric oxide.These gas are making carbonic acid and nitric acid and these acid are responsible for acidification in sea. For this reason coral are dying day to day and some are dead in nature.

(healthy coral)

 

(Dead coral)

 

(Dying coral)

Great barrier reef suffered a catastrophic die-off of coral during an extended heatwave in 2016,threatening a broader range of reeflife than previously feared.
coral bleaching due to warming sea temperatures linked to climate change.The reef is also under threat from the coral eating crown oF thorns starfish which has proliferated due to pollution and agriculture reen off.The crown of thorn starfish found in coral reef in the indospecific regions.
crown of thorns starfish spawn during the warmer month(oct-feb) with large females capable of producing upto 65million eggs over the spawning season.On healthy coral reef,the coral eating starfish plays an important role as it tends to feed on the fastest growing corals such as staghorn and plate corals allowing slower growing coral species to form colonies.This helps increase coral diversity.How ever out breaks of the venomous starfish pose one of the most signification threats to the great barrier reef.
with heavy use of coal fired power and relatively small population,australia is considered one of the the world's worst per capita green house gas polluters. 

 Prevention:-
Improving water quality,tacklimg predators and expanding restoration efforts.Canberra insists taking strong action to address the global(threat climate change,having set an ambitious target to reduce emissions by 26-28% from 2005 levels by 2030.
to improve water quality by changing farming practices and adopting new technologies and land management.working with farmer to prevent sediment ,nitrogen and pesticide reenoff into the reef.
handle the crawn of thorns.Work with traditional aboriginal owners,the tourist industry,farmer and scientist to save the reef.