Staring Bryozoans as the Canary-In-The-Mine in “THE SOURING OF THE OCEANS”
Some of the most beautiful filter feeders in our oceans are the bryozoans (watch them here). Bryozoans are a diverse looking lot. Some look like tiny stiffened feathers (e.g. Pterocella scutella), whilst others form exquisitely patterned crusts (eg Membranipora membranacea). What they share is a common threat from the oceans souring. The souring of our oceans may sound a lot like a science fiction dystopia. However, the oceans have already soured since the industrial revolution, and are set to sour further.
Ocean acidification, the proper name for this souring, is a result of increased carbon dioxide in the atmosphere. Since the industrial revolution carbon dioxide has increased by 40 percent in the atmosphere. Oceans absorb carbon dioxide from the atmosphere. When atmospheric carbon dioxide dissolves in water it changes the chemistry of the sea water, reducing the concentration of carbonate ions and making it more acidic (the pH of seawater has decreased by 0.3 units since the industrial revolution). Watch this video for a brief outline of ocean acidification.
So what does this mean for bryozoans? Bryozoans produce their skeletons from a range of calcium carbonate compounds. Their ability to secrete and maintain these skeletons is likely to be affected by ocean acidification. The diversity in morphology and skeleton composition suggests bryozoans will have a broad range of vulnerability to ocean acidification.
Fiona Hodge, 3 NEWS, 21 May 2010. Full article and video.