Reef Report for Thursday, March 6, 2008
Increasing Carbon Dioxide Levels Connected with Lowered Coral Growth Rates.
One more reason to reduce your Carbon footprint.
We have been following the discussion of the connection between increased levels of Carbon Dioxide in our atmosphere and increasing acidity of the worldís oceans for some time now, but a news article published today connected increased ocean acidity with decreased coral growth rates.
Given our interest in coral reefs worldwide, that prompted the writing of this piece.
The first part of the story is basic chemistry. No one has ever disputed the fact that increased levels of carbon dioxide in our atmosphere increased the amount of carbon dioxide that naturally dissolves into our oceans. Itís been estimated that 118 billion metric tons of carbon dioxide has been absorbed by our oceans between 1800 and 1994, and millions of metric tons more since 1994.
Carbon dioxide, when dissolved in water forms a weak acid. The more carbon dioxide that gets dissolved, the more acidic the ocean becomes; thatís been a measurable change over the past 50 years.
For a long time scientists have discussed the possible impacts on increasing ocean acidity on marine life, and much of that focus has been on corals and other organisms that use Calcium Carbonate to build the hard parts of their bodies, for instance the hard skeletal parts of coral. Carbonate and calcium are both dissolved in ocean water. Corals and other animals remove carbonate and calcium from the ocean, then combine them into calcium carbonate, which forms the hard structural parts in their bodies.
Scientists theorized that increasing acidity could decrease the ability of these organisms to remove carbonate from ocean water, but until recently have not been able to demonstrate that this was happening.
Dr. Janice Lough, a scientist with the Australian Institute of Marine Science, has just published the first research showing this connection. In her study comparing growth rates in a long-lived coral species found on the Great Barrier Reef, she learned that the current growth rates of these corals is 20% less than the historical average.
Obviously much work needs to be done to more completely understand whatís happening, but anything causing such a decrease is cause for concern and further investigation.
Personally, Iíd add that itís also a reason to look at how our personal activities may be contributing to the problem. Any change in your life that decreases the amount of fossil fuel that you use would be part of any long term solution to the problem.
This afternoon I am headed into town 15km away to take part in a sports competition, Iíll be doing that by bicycle, (the official and only DiveTheReef.com car is a bike!); why not consider leaving your car at home?
Brisbane Courier Mail coverage of this story. .
Background information on Professor Lough, who performed this research. .
Ocean Acidification, from the Australian Institute of Marine Science .
More background information on ocean acidification..
The weekly reef report is written by Joel Groberg of DiveTheReef.com,
who compiles them from the many conversations he has with dive staff in the area, as well as† many other local sources in the dive
Index of all reef reports.