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What is the news?
As per a report, world lost its 14% coral reefs in last 10 years. The reason being ocean-acidification, warmer sea temperatures and local stressors such as overfishing, pollution, unsustainable tourism and poor coastal management.
The report by Global Coral Reef Monitoring Network (GCRMN) was drawn from a global dataset gathered by over 300 members of the network covering four decades from 1978 to 2019.
What are the key findings of the report?
Coral reefs across the world are under relentless stress from warming caused by persistent rise of land and sea temperatures due to climate change. Coral bleaching events caused by rise in elevated sea surface temperatures (SST) were responsible for coral loss. Large-scale coral bleaching events were responsible for killing 8% of the world’s corals in 1998.
Decrease in hard coral cover: There has been a steady decrease in hard coral cover in the last four decades since 1978 when the world lost nine per cent of its corals. The worst-hit are the corals in South Asia, Australia, the Pacific, East Asia, the Western Indian Ocean and the Gulf of Oman. The decrease is disconcerting because live hard coral cover is an indicator of coral reef health.
Increase in algae on coral reefs: Since 2010, the amount of algae on the world’s coral reefs has increased by about 20 per cent. Algal bloom on coral ridges are a sign of stress on the structures. Prior to this, on average, there was twice as much coral on the world’s reefs as algae.
This transition from live hard coral to algae-dominated reef communities impacts marine habitats, rendering them less biodiverse and also affects the ecosystem services provided by them.
What are some positive findings in the report?
Coral reefs in east Asia’s Coral Triangle accounts for more than 30 per cent of the world’s reefs but has been less impacted by rising sea surface temperatures.
Despite a decline in hard coral cover during the last decade, on average, these reefs have more coral today than in 1983, when the first data from this region were collected, the scientists noted.
In 2019, the world regained 2% of its coral cover in spite of a short interval between mass coral bleaching events in the last decade.
These instances mean that these critical ecosystems have the capacity to recover if pressure on them eases, the researchers noted. They can even resuscitate to their pre-1998 health in the next ten years, the report mentioned.
Why are corals significant?
Though corals occupy less than 1% of the ocean floor but over one billion people benefit directly from the reefs.
The value of goods and services provided by coral reefs is estimated to be $2.7 trillion per year including $36 billion from coral reef tourism.
As per some reports, the net economic value of the world’s coral reefs could be nearly tens of billions of dollars per year.
Source: This post is based on the article “Climate change: 14% coral reefs lost since 2010, says study ” published in The Down to Earth on 5th October 2021.