This coral reefs they are in danger. HE climate change causes a significant reduction in these structures. biodiversity and a vital role in marine ecosystems. A new study shows very worrying results: despite the coral’s great natural adaptability, even moderate global warming can lead to the destruction of reefs.
“We discovered that The natural adaptive capacity of corals is not sufficient to prevent the erosion of reefs due to climate change.‘, points out Christopher Cornwall of the Victoria University of Wellington (New Zealand).
It won’t be possible to save corals unless they stop spreading. greenhouse gases immediately and start developing techniques removing gases from our atmosphere“warns the biologist.
Coral colonies are supported by a hard calcium carbonate skeleton similar in structure to vertebrate bones and surrounded by soft ‘polyps’ resembling anemones. Inside these polyps live tiny, microscopic algae that provide nourishment to the corals.
yes ok coral has a very long generation time Limiting their ability to evolve in response to climatic stress (years to decades), algae have much shorter production times that allow for rapid evolution. Some algae are more heat tolerant and corals can “select” them by absorbing those that are more heat tolerant.
The paper, which includes the results of research published in the journal ‘Global Change Biology’, reveals how calcium carbonate production can change under the influence of climate change, with or without coral evolution. tolerance of reefs to warming sea water.
Confirmed the worst omens
The researchers analyzed how calcium carbonate production would be affected by three different emission scenarios (and thus warming and acidification) between 2050 and 2100: temperate (between 0.7 and 0.98°C), most probably (between 0.87 and 1.59°C) and pessimistic (1 and 2.43°C).
The results show that average growth The percentage of coral reefs at sites studied globally remained positive only under moderate warming below 0.98ºC. But with nuances.
“Only 9% to 35% of reefs will continue to grow in moderate scenarios in 2050, but All would be eroding in the Atlantic and Indian oceans. Unless greenhouse gas emissions are reduced immediately, only 9% to 13% growth will continue through 2050.
The research confirms the worst omens: “The natural adaptive capacity of coral can only warrant slightly higher growth rates in lower emissions scenarios,” he says.
“In the worst case scenario, only 6 of the 201 reefs we examined could survive”Warn Cornwall. so there is one “urgent need” to reduce greenhouse gas emissions to protect the reefs in the long run.
Protecting coral reefs is crucial to biodiversity: an important part of ecosystems in tropical and subtropical regions, to house almost a quarter of marine life And helps protect coastlines from erosionIt creates a barrier between the ocean and the coast.
“We’ve seen a lot of damage from massive coral bleaching events caused by marine heatwaves, but their ability to survive and continue to grow will be greatly impacted by continued warming,” says the biologist.
more heat resistant species
“Many corals will not adapt fast enoughand we could lose almost all or all of its ecological function worldwide.” more heat tolerant species with high rates of calcium carbonate production in the most risky habitats.
“The challenge is that the most heat tolerant species are the slowest growing species, and the fastest growing species are the most heat sensitive. So, really, The best solution – perhaps the only solution – is to keep the warming below 1.5ºC and invest in CO2 removal.says Cornwall.
Among the effects of climate change on corals, whiteningoccurs when they remove symbiotic algae (zooxanthellae) that live in their tissues and provide them with food and color. Without them, corals can become more susceptible to disease and die.
It causes an increase in CO2 in the atmosphere. ocean acidificationdissolves in sea water to form carbonic acid. This reduces the availability of calcium carbonate, which is essential for the formation of coral skeletons, which inhibits their growth and development.
Global warming also contributes rising sea levelsIt harms corals and their reefs as it reduces the amount of light reaching their surface area and limits their vertical growth.
Increased frequency and intensity extreme weather eventstropical storms and hurricanes can cause physical damage to corals and their reefs.
As a result of these factors, many coral reefs are in a state of stress or suffered serious damageand observed decrease in biodiversity and coral cover in many areas.
Reference report: https://onlinelibrary.wiley.com/doi/10.1111/gcb.16647
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