AP Biology class blog for discussing current research in Biology

Effect of ocean acidification: Coral growth rate on Great Barrier Reef plummets in 30-year comparison


A new marine biological study conducted in Australia shows a correlation between rising ocean acidification levels and declining coral growth rates in the Great Barrier Reef. Scientists Ken Caldeira and Jacob Silverman carried out research testing growth rates from samples of current coral on the reef and records from the 1970’s. The findings were astounding. According to the comparison, coral growth rates have declined by almost 40% since the 1970’s and the scientists believe they have an explanation.

Coral produce their exoskeleton by utilizing aragonite, a naturally occurring calcium carbonate (CaCO3). This process is called calcification. However, when acid levels in the water become too high, the environment for producing healthy coral becomes compromised. Since the beginning of the Industrial Revolution about one third of all CO2 released into the atmosphere has made its way into the oceans. This lowers the Ph, causing the water to become more acidic, and creates an environment ill suited for coral growth. The scientists speculate that this acidification of the water is whats leading to decreased growth rates in not only coral, but also many other species of marine life.

Coral plays a vital role in underwater ecosystems, providing food sources and shelter for nearly 25 percent of all marine life. Some reefs admired and studied by scientists today began growing nearly 50 million years ago. There is no question that coral’s role is vital in the fabric of the ocean. However, recent studies similar to the research done by Caldeira and Silverman are prompting scientists to worry deeply about the future of our oceans. When quoted on the status of reefs today, Caldeira stated, “Coral reefs are getting hammered. Ocean acidification, global warming, coastal pollution, and overfishing are all damaging coral reefs. Coral reefs have been around for millions of years, but are likely to become a thing of the past unless we start running our economy as if the sea and sky matters to us very soon.”

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  1. andybody

    Yes struan, great post. It’s disheartening to read about how so many species, and environments are being destroyed as a result of humanities disregard for nature. I wonder if people suddenly decided to “go green” and to consistently strive to not buy plastics, recycle, buy hybrid cars, change the ways factories produce toxins etc., would it be enough to sort of “right the ship” for nature? If all the negative effects of industrialization no longer existed would nature be able to heal itself, or are the effects such as those in your article permanent and irreparable. This article ( suggests that nature is capable of healing itself: however we are damaging it a far too rapid rate.

  2. Lord of the blood cells

    Great post struan. It is crazy to think about how vast and rich in life the ocean is. The places most abundant in marine life are coral reefs. Toxic acids that are hurting the health of coral polyps are a huge problem and should be dealt with as Caldeira says. Take a look at this conservationist website where it explains how some improper and unethical fishing techniques are literally killing coral reefs and their marine life:

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