Research published last Wednesday indicates that the destruction of the Great Barrier Reef caused by excessive heat has made it impossible for the reefs to recover. Climatic change is expected to make the situation worse.
High temperatures cause bleaching of the world’s largest coral reef in Australia that is over 1400 miles long. The coral reefs have “bleached” four times in two decades which includes back to back episodes that happened in 2016 and 2017.
On Wednesday, Scientists researching the reefs posted on journal Nature that it was not easy to avert the situation. They have also found out that the situation will become worse due to the increase in heat making it impossible for the reefs to recover.
Terry Hughes says that the ability of the reefs to replenish is at a standstill. Hughes is the director of the Australian Research Council Center of Excellence for Coral Reefs. She is also the head author of the study’s findings.
She adds that the coral reefs are struggling to overcome the effects of bleaching due to high temperatures. She agrees with the findings of the researchers that dead corals don’t reproduce.
The high temperatures affect over half of the Great Barrier Reef which was composed of almost 3000 reefs between 2016 and 2017. Specific species die at a higher rate compared to others.
Coral bleaching occurs due to excessive heat that leads to the depletion of symbiotic algae located in coral cells which provides them with nutrients. Scientist discovered that moderate bleaching is manageable while excessive bleaching leads to the death or vulnerability of coral reefs to diseases.
In the past, once bleaching or hurricane has led to the damage of coral reefs; the adult coral reefs give rise to many larvae which spread and replenish thereby replacing the dead corals. It has happened ones in the past but it is not happening nowadays.
The study published on Wednesday shows that the rate at which new corals are replenishing has declined by 89 percent due to the occurrence of bleaching events. For a coral to recover, it takes at least ten years even for those that grow very fast. Therefore, for a coral to return to its former state, it will take an extended period.
The study also indicates that they speculate that corals will bleach twice in a decade until 2035. After that, they will bleach every year after 2044 if the greenhouse gas emission is not averted. Since 1998, the Great Barrier Reef has suffered four significant bleaching events. Due to the continued change in climate, there will be no break for the reef.
Morgan Pratchett, a professor at James Cook University, says that they thought that the Great Barrier Reef would never fail due to its magnitude but it is until now they have learnt that it can fail.
Kim Cobb, a scientist with extensive knowledge in coral reefs at Georgia Tech University, says that the process of gathering data in the study is “painstaking” and that the results are “devastating.” She adds that it is a problem that they didn’t think of due to the repeated events caused by a change in heat patterns.
She states that questions are emerging on if the failure of the Great Barrier Reef to reproduce is going to be a short term effect or whether the corals will get adapted to climate change. She asks whether there is enough time for the coral reefs to recover making them more resilient to overcome the next heat change.
The journal Science indicates that coral reefs were bleaching four or five times more than they are bleaching before the 1980s.
Mark Eakin is involved in coordination of National Oceanic and Atmospheric Administration’s Coral Reef Watch. He says that he is seeing 90 percent of reefs experiencing excessive heat leading to bleaching annually.
The study used more than 100 coral reefs in the survey. Between 1980 and 2016, the results indicated that very few reefs had not suffered bleaching. The rate of bleaching is increasing with time. It also showed that a single reef bleached ones in every 25 years before the 1980s but after 2016, the bleaching period was 5.9 years.
Hughes adds that not only are the coral reefs are under threat but the whole ecosystem especially marine organisms. Reefs protect coastlines from storms. Due to industrial activities, temperatures have increased by one degree Celsius and they will continue to rise with the increased release of more carbon dioxide. The report indicates that high temperatures that have exceeded by two degrees Celcius are leading to the loss of coral reefs.
Hughes states that scientists should not assume that reefs will be affected in future as they have been affected in the past. The effects will become worse since reefs in the past were more resistant to high temperatures. The nature of coral reefs is already changing. Researchers have been anticipating climatic changes will affect coral reefs but it is already happening.
