The impact of excess carbon dioxide on coral reefs

How does excess carbon dioxide in the air impact coral reefs?  

The chemistry class from the Secondary Program  at the Perkins School for the Blind learned about this first hand from scientists, staff, and graduate students at the Woods Hole Oceanographic Institution on Cape Cod, Massachusetts.  Working with Dr. Heather Benway, students measured the pH level of ocean water.  As the voice output of the Vernier sensors* reported, the water was not acidic at all in fact it was slightly basic, slightly above a neutral reading of 7 at 7.8.   Then each student added ph sensorcarbon dioxide to the water by blowing bubbles into the salt water.  Then follow up readings were taken.  The water had changed! It now registered in the acidic range!!  
 
The carbon dioxide levels of ocean water are rising because the excess carbon dioxide in the air dissolves in the ocean water. As more carbon dioxide dissolves, fragile ecosystems such as coral reef as are affected. So what does this mean?  Simply put the acidity interferes with the formation of the coral’s calcium carbonate  “skeleton”.  It also interferes with the formation of the shells of clams and oysters. 
 
After the experiment, the students discussed ways to decrease the output of carbon dioxide into the atmosphere including planting trees, driving less, and supporting use of non fossil fuels.  The field trip also included a walk over to the shore to collect sea water for experiments back in the lab at school, a chance to hold a variety of sea creatures, and an opportunity to build models of coral reefs.  
 
For more about our collaboration of 8 years with WHOI contact kate.fraser@perkins.org.  
 
* The Vernier sensors have been adapted and are available from Independence Science.
 
 
 

 

 
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