Corals are tiny marine invertebrates that typically live in colonies, secreting calcium carbonate to form a hard skeleton. These iconic creatures are increasingly threatened by climate change — most notably by related increases in seawater temperature. As part of a warming climate, the amount of dissolved carbon dioxide in the surface ocean also increases.
This in turn boosts the acidity of the water and produces chemical conditions in the ocean that absorb some of the carbonate that marine organisms need to grow their skeletons and shells. Reef-forming corals are marine animals that produce a hard skeleton made up of aragonite, one form of the mineral calcium carbonate. But how the skeletons grow has remained unclear. A different model, proposed by Gilbert and colleagues in and based on a study of one species of coral, suggests instead that undissolved nanoparticles attach and then slowly crystallize.
In the first part of a new study, published Nov. PEEM chemical maps of calcium spectra allowed the scientists to determine the organization of different forms of calcium carbonate at the nanoscale.
PEEM results showed amorphous nanoparticles present in the coral tissue, at the growing surface, and in the region between the tissue and the skeleton, but never in the mature skeleton itself, supporting the nanoparticle attachment model. However, they also showed that while the growing edge is not densely packed with calcium carbonate, the mature skeleton is — a result that does not support the nanoparticle attachment model.
The researchers next used a technique that measures the exposed internal surface area of porous materials. But they are expected to creep toward 7. Using a scanning electron microscope and other measurement devices, the scientists examined the proteins and found that all had begun to precipitate calcium carbonate crystals in the test tube at both pH levels. The National Science Foundation supported the research. Source: Rutgers. Search for:.
Science Health Culture Environment. Share this Article. Coral skeletons are made of aragonite, a form of calcium carbonate. To grow up toward sunlight, corals construct a framework of aragonite crystals. At the same time, they buttress this framework with bundles of additional crystals, which thicken and strengthen the skeletons to help them withstand breakage caused by currents, waves, storms, and boring and biting by worms, molluscs, and parrotfish.
Ocean acidification is caused by rising levels of carbon dioxide in the atmosphere, mostly from burning fossil fuels. Laboratory experiments and field studies, however, have shown that acidification affects skeletal growth in some cases, but not in others. Something Mollica had never envisioned he would be doing in his career. Mollica grew up in Fort Collins, Colo.
I said, I would, because I thought it would get me out of a tight spot with my parents. His high school team won regional, then state, competitions, and went to the national Science Olympiad every year.
He also competed in a Jeopardy-style competition called the Science Bowl. His favorite subject was geology, which led him to apply to the Colorado School of Mines. The school was primed to train students to go into applied fields in the oil and gas industry or civil engineering.
More specifically, the lab focused on how corals are affected by their environment, and how that, in turn, affects their ability to produce carbonate skeleton. Coral reefs have persisted through geological history and built most of the carbonate geology that there is.
It was cool to be handed what I was looking for without knowing what I was looking for. I never thought I was going to be an oceanographer—right up until it happened. Among the first things Mollica had to do when he arrived at WHOI was take a month-long course to learn how to scuba dive for his research. He and colleagues dove on reefs and used a drill to extract tubular, 3.
From the scans, they could discern the upward and thickening components of the coral growth. Their analyses revealed that skeletons of corals in more acidic lower pH and fewer carbonate ions waters were significantly thinner.
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