Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

Ocean Acidification Causing Coral Reefs to Be Less Resilient to Climate Change

Oceans
Divers search the coral reefs of the Society Islands in French Polynesia on May 9, where major bleaching is occurring and scientists are studying the resilience of coral. Alexis Rosenfeld / Getty Images

A changing climate is altering oceans in major ways and coral reefs around the planet may not be able to adapt to survive.


Ocean acidification (OA) occurs when carbon dioxide from the atmosphere is absorbed by seawater, resulting in a chemical reaction that reduces pH and calcium carbonate levels vital for the growth and repair of calcifying organisms like coral, explains the National Oceanic and Atmospheric Association. Publishing their work in Nature Climate Change, researchers examined four species of coral and two types of calcifying algae over the course of the year in order to determine how they might bounce back from stressful conditions.

"We found that corals and coralline algae weren't able to acclimatize to ocean acidification," said study author Malcolm McCulloch, adding that that the effects were rapid and persistent.

At least one-quarter of carbon dioxide in the atmosphere from coal, oil and gas dissolves in the ocean, according to the Smithsonian Institute. Changes in the ocean's chemistry since the Industrial Revolution have been recorded at an unprecedented rate. In the last two centuries alone, ocean water has become 30 percent more acidic — not even natural buffering can keep up.

Because seawater contains high levels of dissolved substances, Woods Hole Oceanic Institute notes that ocean waters have a slightly alkaline, or basic, pH of around 8.2. As more carbon builds up in the atmosphere, we see higher levels being absorbed in seawater to form carbonic acid, which breaks down to become more acidic as the pH level drops. Calcifying organisms like coral grow by adding calcium carbonate from the seawater to their shells or skeletons, but the researchers note that some species are disproportionately affected in their ability to repair or grow as these levels drop.

"The results also confirm that Ocean acidification could have repercussions on the competition between species which could, in turn, affect the ecological function of reefs," said lead author Steeve Comeau. In their findings, two of the species were found to be resistant to OA from the start of the experiment while two others were too sensitive to acclimate. Those species that were able to adjust have different physiological mechanisms at play, but the team notes that they aren't sure what they are or how they work.

Coral respond to bleaching events caused by stress from pollution, overexposure to sunlight, extreme low tides, and changes in ocean temperatures by repairing via this calcification process. However, a 2018 study found that OA impedes the thickening or growing process of coral and decreases skeleton density, making them more vulnerable to breaking. Climate change and the advent of the Anthropocene are only expected to worsen these effects. Oceana notes that before the Industrial Revolution, about 98 percent of coral reefs were surrounded by waters with ideal levels of aragonite, but today the proportion is less than half. A study published reported by CBS found that climate change has caused an 89 percent decrease in new coral in the Great Barrier Reef, further validating that coral reefs are threatened by climate change and its repercussions.

Long-term assessments of OA are scarce and the scientific community is limited in its understanding of how it impacts corals and coralline algae. We do know that if there is a 20 percent increase in current carbon dioxide levels over the next two decades, corals will grow slower and will be less able to overcome even normal pressures.

EcoWatch Daily Newsletter

By Michael Svoboda

The enduring pandemic will make conventional forms of travel difficult if not impossible this summer. As a result, many will consider virtual alternatives for their vacations, including one of the oldest forms of virtual reality – books.

Read More Show Less
Public Employees for Environmental Responsibility on Thursday accused NOAA of ignoring its own scientists' findings about the endangerment of the North Atlantic right whale. Lauren Packard / Flickr / CC BY 2.0

By Julia Conley

As the North Atlantic right whale was placed on the International Union for Conservation of Nature's list of critically endangered species Thursday, environmental protection groups accusing the U.S. government of bowing to fishing and fossil fuel industry pressure to downplay the threat and failing to enact common-sense restrictions to protect the animals.

Read More Show Less
Pexels

By Beth Ann Mayer

Since even moderate-intensity workouts offer a slew of benefits, walking is a good choice for people looking to stay healthy.

Read More Show Less
Much of Eastern Oklahoma, including most of Tulsa, remains an Indian reservation, the Supreme Court ruled on Thursday. JustTulsa / CC BY 2.0

Much of Eastern Oklahoma, including most of Tulsa, remains an Indian reservation, the Supreme Court ruled on Thursday.

Read More Show Less
The Firefly Watch project is among the options for aspiring citizen scientists to join. Mike Lewinski / Wikimedia Commons / CC by 2.0

By Tiffany Means

Summer and fall are great seasons to enjoy the outdoors. But if you're already spending extra time outside because of the COVID-19 pandemic, you may be out of ideas on how to make fresh-air activities feel special. Here are a few suggestions to keep both adults and children entertained and educated in the months ahead, many of which can be done from the comfort of one's home or backyard.

Read More Show Less
People sit at the bar of a restaurant in Austin, Texas, on June 26, 2020. Texas Governor Greg Abbott ordered bars to be closed by noon on June 26 and for restaurants to be reduced to 50% occupancy. Coronavirus cases in Texas spiked after being one of the first states to begin reopening. SERGIO FLORES / AFP via Getty Images

The coronavirus may linger in the air in crowded indoor spaces, spreading from one person to the next, the World Health Organization acknowledged on Thursday, as The New York Times reported. The announcement came just days after 239 scientists wrote a letter urging the WHO to consider that the novel coronavirus is lingering in indoor spaces and infecting people, as EcoWatch reported.

Read More Show Less

Trending

A never-before-documented frog species has been discovered in the Peruvian highlands and named Phrynopus remotum. Germán Chávez

By Angela Nicoletti

The eastern slopes of the Andes Mountains in central Perú are among the most remote places in the world.

Read More Show Less