In a new study, researchers have found that increasing acidic oceans will severely harm coral reef growth over the next few decades if carbon dioxide emissions continue at a rate similar to now.
The study, published in the the journal Nature, was conducted at One Tree Island in Australia’s Great Barrier Reef. Scientists pumped CO2 onto a section of coral in the reef to simulate levels of ocean acidification expected to occur by 2050.
This was the first experiment in which seawater was made artificially acidic by addition of CO2 and allowed it to flow across a natural coral reef.
After the additional CO2 was applied, the researchers measured the effect it had on a process known as calcification, which is a structure of calcium that corals and reef organisms use as their structure. They found that there is a about a 30 percent decrease in calcification after the C02 was applied.
The study, led by Dr Rebecca Albright, assistant curator at the California Academy of Science, was the first to investigate the impacts of ocean acidification on an entire natural reef system.
“Our findings provide strong evidence that ocean acidification will severely slow coral reef growth in the future unless we make steep and rapid reductions in greenhouse gas emissions.”
She said there was a much greater effect than found in previous studies of acidification on coral growth, most of which saw a decrease of 15 per cent. But Dr Albright said most of the previous studies had been done in the lab on individual coral species, and this did not reflect the complex reef ecosystem.
“Coral reefs are so much more than just corals,” she said.
Some algae, sponges and other reef inhabitants are also involved in the calcification process.
The findings are so alarming when considering that this large of an impact seen on the reefs was cause by a vert tiny change in acidity- a reduction of pH by 0.1.
Ocean acidification, the shifting of the ocean’s water toward the acidic side of its chemical balance, has been driven primarily by climate change. Since the start of the Industrial Revolution in the 1800s, the world’s oceans have already grown nearly 30% more acidic.
Many already knew that ocean acidification would harm coral but did not exactly know to what extent. The findings from this study can be used to try and figure out practical solutions to try and combat the loss of coral reefs and grow new coral through accelerated growth technology.
The team hopes their findings trigger researchers to use more realistic carbon dioxide levels in future experiments.
Reefs are vital the survival of our oceans ecosystems as they are one of the most biologically diverse ecosystems on earth, rivaled only by tropical rain forests.
They are also pivotal to coastal protection and reducing erosison. It was recently discovered that loss of coral reefs is a larger threat to coastlines than rising sea levels.
Besides the threat of acidification, coral reefs are also battling coral bleaching. Bleaching occurs when ocean waters warm, causing the algae living in their tissues to be expelled. Corals can survive bleaching events but are much more susceptible to disease, stress, and mortality.