Acidity threatening our reefs...

http://www.newsnet5.com/dpp/news/science_tech/science-official-ocean-acidity-major-reef-threat-wcpo

I've heard for years that temperature rising is a huge concern, but I never thought about rising acidity levels...

Oh yes. A very interesting problem. Some people suggest it will cause an evolutionary change in the material corals build themselves with. It's happened in the past.

It's kind of a long article, but this is an excerpt

Reefs are large underwater structures of coral skeletons, made from calcium carbonate secreted by generation after generation of tiny coral polyps over sometimes millions of years of coral growth in the same location. The team showed that corals can switch from using aragonite to another mineral, calcite, in making the calcium carbonate. They make that switch in response to decreases in the ratio of magnesium to calcium in seawater, Ries said. That ratio has changed dramatically over geologic time.

Though most scientists believed that corals were programmed to produce only the aragonitic form of calcium carbonate, he said, the team's work reveals that corals are far more flexible and able to vary at least a portion of their skeleton to growth favored by seawater chemistry. He postulates that this "mineralogical flexibility" provides corals with an "evolutionary advantage," as it would take more energy for corals to produce skeletons that are not favored by the chemistry of the seawater surrounding them

http://www.sciencedaily.com/releases/2006/07/060706095218.htm

Very cool! I didn't know corals could switch like that to build their skeletons. I can't imagine a world without reefs, so it's comforting to know that corals have some tricks up their sleeves. We need to do our conservation part too though.