Coral reefs and the vital ecosystem support they provide to the oceans, fish, and humans have declined by about half since the 1950s. a new study has found out.
Scientists at the University of British Columbia (UBC) in Canada have collected a range of data from coral reef surveys and fishery catches to assess the impact the world’s dwindling corals are having on food webs and ecosystems.
The researchers found that the enormous loss of living corals in the oceans – around 50 percent since the 1950s – is offset by a corresponding decline in the “ecosystem services” of these reefs.
“Coral reefs are known to be important habitats for biodiversity and are particularly sensitive to climate change, as heat waves in the ocean can cause bleaching,” said Tyler Eddy, one of the scientists involved.
“Coral reefs offer people important ecosystem services through fishing, economic opportunities and protection from storms.”
The study suggests that coral reef fishing peaked nearly 20 years ago and has since declined, although efforts to extract fish from these parts of the ocean have increased.
In addition to the total number of falling fish, the diversity of species living on reefs has collapsed by more than 60 percent.
“Our analysis shows that the capacity of coral reefs to provide ecosystem services has declined by about half worldwide,” said William Cheung, professor at the UBC Institute for the Oceans and Fisheries and lead author of the study. “This study shows the importance of how we manage coral reefs not only at the regional level, but also at the global level, and the importance of the livelihood of the communities that depend on them.”
Coral reefs, which are made up of tiny living organisms called polyps, cover only one percent of the earth’s surface, but are vital building blocks of a healthy marine ecosystem. By providing food and habitats for breeding and growing areas, they support around 25 percent of all marine life, including over 4,000 species of fish.
They also benefit people, not only by feeding millions of fish, but also by protecting coastal communities from waves and storms.
However, corals are threatened worldwide, mainly because of climate change. Rising ocean temperatures cause tiny algae called zooxanthellae – which provide most of the corals’ food and nutrients – to be expelled from their hosts, which in turn gradually kills the reef, turning its normally bright colors to a dull white.
This bleaching of the coral reefs turns them from a critical life support system for marine life to an oceanic graveyard.
The study’s authors also warned that coastal indigenous human communities that rely on coral could be threatened by the ongoing destruction of the world’s reefs.
“Fish and fisheries provide essential micronutrients in coastal development regions with few alternative food sources,” they wrote. “Coral reef biodiversity and fisheries are becoming increasingly important to indigenous communities, small island developing states and coastal populations where they can be essential to traditions and cultural practices.
“The reduced capacity of coral reefs to provide ecosystem services undermines the well-being of millions of people with historical and enduring relationships with coral reef ecosystems.”