The Australia's Great Barrier Reef is the world's largest coral reef. It has lost half of its coral reef in little more than a generation and it is declining faster than ever .The coral cover is at a high risk of falling to 5 percent , some studies and researchers from the Australian Institute of Marine Science (AIMS) in the northeastern city of Townsville shows.
The coral reef is under threat from Australia's surging coal, gas shipments, climate change, particularly rising sea temperatures, increased ocean acidity, more powerful storms,and a destructive starfish, AIMS noted.
AIMS scientists said that the cyclone damage caused almost half the losses, crown-of-thorns starfish caused more than 40 percent and coral bleaching from spikes in sea temperatures caused 10 percent.
The water of the seas is absorbing more and more carbon dioxide causing the ocean acidification to rise. This acidification
is disrupting the ability of corals to build their calcium carbonate structures.
Climate change like increasing of the ocean temperatures, the storm activity, the ocean acidification, and the sea-level rise determine the coral bleaching and the diseases. Increasing the atmospheric carbon dioxide has already begun to reduce the calcification rates in reef-building and reef-associated organisms by altering sea water chemistry (ocean acidification).
Greens say the centre-piece of a multi-billion tourism industry faces a growing threat from shipping driven by the planned expansion of coal and liquefied natural gas projects.
Shipping and new ports on the Queensland coast are another major threat, Greenpeace says.
''Coal is one of Australia's top export earners and the state of Queensland is the country's largest coal-producer. It also has a rapidly growing coal-seam gas industry for LNG exports.'',Reuters noted.
Overfishing, direct exploitation of fish, invertebrates, and algae for food and the aquarium trade has lead to the depletion of key functional fish, invertebrates, and algae species in specific locations having cascading impacts on coral reef ecosystems.
The removal of a group of species is impacting multiple levels.
The suite of problems regarding coral reef ecosystems from land-based sources of pollution subsumes the sediment, the nutrients, and other pollutants being a result of the land-based activities. These pollutants are transported in surface waters, runoff, groundwater seepage, and atmospheric deposition into coastal waters causing some diseases and even death in sensitive coral species. They impede the coral growth, their reproduction, and the settlement of the coral larvae.
Gunn said that there are methods to improve the water quality from rivers flowing into the reef area.
NOAA has a clear role to monitor the climate change and the ocean acidification by reducing the greenhouse gases (primarily carbon dioxide).
Forty years ago, the Caribbean area had lost half of its coral.. After decades of human impacts, only remote reefs in the region show coral growth up to 30 percent.
The decline of algae-eating species like parrotfish and sea urchins, have left many reefs overrun by stifling algae.Symbiotic algae, zooxanthellae, leave the coral when water heats up, an occurrence known as bleaching. Zooxanthellae are living inside the corals and are assisting in providing nutrients and aiding photosynthesis.
Overfishing is still an issue in some places like Jamaica, and nutrient runoff pollution from land is a problem in U.S. Virgin Islands.
Coral reefs are made from calcium carbonate secreted by coral polyps and support intricate food chains of invertebrates and fish species. Furthermore, fishes provide certain nutrients that the coral feeds on, helping it maintain itself and grow. Some fishing practices can damage the coral reef. Pollution like oil spills negatively affects the coral reefs. Fertilizers and pesticides used in farming practices are transported in surface waters of the sea and cause algae to flourish. This algae deplete oxygen levels in the water. Deforestation and industrial development can cause silt, soil and sediment to wash into the ocean .This fact can increase the turbidity in the water preventing sufficient sunlight from reaching the coral.
The range from sewage belonging to tourist resorts is washed directly into the sea affecting the coral reefs. The divers and the snorkelers are breaking off many pieces of coral used as souvenirs.
The oceans have absorbed much of carbon dioxide affecting the pH balance of seawater and making seawater be more acid than before. This carbon dioxide has reduced the availability of carbonate ions, an essential chemical in the formation of coral.
An increased ultraviolet radiation caused by the greenhouse gases is depleting the ozone layer . This increase in greenhouse gases is caused by industrial byproducts.
Another cause is the transfer of foreign species in ballast water .
There is a clear evidence that major glaciers have retreated much more in the past than their current levels and that they expended again, only to retreat again starting about 250 years ago. As a result of regional climate change, the African sub tropical glaciers really started to shrink in a big way.
''Tropical glaciers exist only at high altitude, and meteorological and surface energy balance studies of these glaciers can tell us much about the conditions and changes occurring in the mid troposphere.'',NASA noted.
These glaciers are a very poor “Canary” since we are in an Interglacial period with remnant glaciers. Since the last Interglacial period has been rather long at a bit over 11,000 years, the disappearance of glaciers is not something that really should be unexpected .