Corals can’t adjust to acidic oceans

coral reef coralline algae ocean acidification

Coral’s development processes are being impacted by climate change.

A year-long study has confirmed that corals and coralline algae are under threat from acidic and warming waters caused by climate change.

Coralline algae are the architects of coral reefs. The organism connects the reef together and acts as a foundation for an array of marine life. The coralline algae also acts as a breeding ground for these species.

However, new research led by scientists from the University of Western Australia, has found that corals and coralline algae can not acclimatise to changing ocean temperatures and chemistry.

The problem, researchers point out, is that if the corals and algae don’t adapt, future reef growth and marine species will be impacted.

Ocean acidification slows development process

Over a year long period, researchers exposed four corals and two calcifying algae to four different carbon dioxide conditions.

The hypothesis was that if the organisms were given enough time, they would be able to adjust to the changing acidity of the oceans.

However, this wasn’t the case. The researchers found that the corals and coralline algae could not adapt to the conditions, even after a year.

Chris Cornwall from the ARC Centre of Excellence for Coral Reef Studies at UWA says that this research shows the negative impact that climate change is having on marine organisms.

“Our research shows that changing ocean chemistry and temperature, caused by climate change, will have negative consequences for coralline algae.”

Acid conditions slow calcification

A main finding from the study was that ocean acidification slows a crucial development process in the organisms, known as calcification.

This means that the organisms capacity to function is negatively impacted.

“Coralline algae may be able to resist short-term changes in ocean temperatures. However, once changes in ocean chemistry occur and cause acidification, their capacity to build and cement together reefs will be compromised,” Cornwall says.

Researchers still are unclear on the physiological mechanisms responsible for the decrease in calcification.

Without coralline algae, we lose native species

Coralline algae plays an important supporting role for many native species in Australian and New Zealand waters, including native New Zealand pāua and kina who use the algae as a nursery.

“Declines in coralline algae could lead to the loss of many other marine species. In New Zealand declines in species of cultural significance like pāua and kina will have profound consequences. In coral reefs, the loss of this cementing algae will further reduce reef growth already impacted by reoccurring mass coral bleaching events.”

“The temperate southern hemisphere has little to no data available on how ocean warming will specifically affect our local coralline algae. We also do not know whether over multiple lifetimes they can gain tolerance to either warming or acidification.”

Researchers hope that with continued efforts they might be able to save these organisms before we lose them, and many other marine species for good.

Australia’s Science Channel, 31 May 2019. Press release.

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