Tracking Climate Change on Coral Reefs

coral growth rates

A student at the NHRCP checks the growth rates of corals on the Hin Fai Biorock

Ocean acidification due to higher carbon dioxide concentrations in the atmosphere is threatening the health of the planet’s marine ecosystems. This is widely understood and accepted, although many questions still remain. .  .How much affect will there be? What percentage of animals will survive? How will this affect human food sources and economies? Is it too late to stop?

Much data is still needed to answer these questions and provide researchers with the information they need to influence changes in policy and management. One way this data is collected is by studying the short and long-term growth of coral reefs, or more accurately the calcification rate of corals. Corals, use energy derived from the sun through their symbiotic algae to deposit alkaline minerals such as calcium carbonate. Calcium carbonate and other minerals (collectively called Argonite) is deposited in the form a limestone like rock to form the coral skeleton, and the base of the coral reef ecosystem.

Carbon dioxide in the ocean is converted to carbonic acid, and makes the waters more acidic. Acidic waters break down and dissolve alkaline minerals such as calcium carbonate. It is feared by scientists that the upper limit for the long-term survival of coral reefs is around 350 ppm of carbon dioxide in the atmosphere, but this year our planet already rose above 400 ppm.

One way that scientists study this effect is by looking at the calcification rate of coral reefs around the planet. Historically, this has primarily been done through direct measurements of the corals or through the analysis of photographic series using computer programs such as CPCe or Image J. This is often difficult and inaccurate to the high complexity of shapes of coral, and the difficulty in repeating measurements or photographs exactly the same each time.

Recently, scientists with the U.S. Geological Survey devised and tested a new method of measuring coral calcification rates not through linear measurements, but by measuring the mass of the corals. Check out an article on this method from ScienceDaily. This new technique provides for a much higher resolution in the data, and less necessary replicates. It is expected by the researchers that this new technique will help deepen and accelerate our understanding of the human caused effects of coral reef decline.

But, it is important to keep in mind that while we need better understanding of the ecosystems and processes, that is not an excuse for a delay in practical actions. The fact remains that human activities and energy production are increasing the concentration of CO2 on our planet, which is driving and uncontrolled and irreversible experiment with our planets environment. Although we need to continue our pursuit of knowledge, more so we need to take action.

There are many things you can do to help the coral reefs, and most of them don’t require you leave your home. Save energy and resources however you can. If you want to learn more about ways that we are trying to research, protect, and restore our local coral reefs check out our marine conservation page.

Clam growth rates

The growth rates of giant clams can also be an indicator for ocean acidification and environmental stresses.