Ocean Acidification – The “Other” Inconvenient Truth

The National Resources Defense Council (NRDC) has just produced a film called “Acid Test: The Global Challenge of Ocean Acidification.”  The short film, which clocks in at about 21 minutes, features narration by Sigourney Weaver who also lent her voice to the recent Planet Earth series (although I happen to have the David Attenborough version, as I have a great deal of reverence for him and his narrative skills).

Most of us think of “carbon” as a buzzword intimately connected to the concept of global warming (the more apt word really is “climate change” as increased CO2 can, through complex and interesting ways, actually lead to cooling trends; but that’s a whole other topic…) but in terms of the ocean can lead to other unfortunate repercussions. The ocean has always been a major sink for CO2 and for quite some time has resisted strong ill effects due to its natural buffering system. A buffering system in chemistry terms allows a liquid (in this case, our “liquid” would be the entirety of the world’s oceans) to resist changes in pH when either acids or bases are added…. to a point. At some level, the system becomes “overwhelmed” and can no longer resist radical changes in pH.

The phenomenon’s name, “ocean acidification”, indicates the oceans are dropping in their pH, increasing in Hydrogen ions, and becoming more acidic in their composition. As more carbon pours into the sea, free carbonate ions (CO3) which are part of the oceans buffering system end up being tied up by the addition of extra CO2 (for the chemistry of this, check out the Center For Ocean Solutions’ Ocean Acidification page – the link is provided in resources at the end of this post). Unfortunately, carbonate is also a very necessary ingredient for the formation of the shells of a variety of organisms – corals, shellfish, pterapods, some types of plankton, etc. The lack of a supply of these carbonate ions actually can cause the shells of these creatures to dissolve, greatly increasing these species’ mortality.

The decalcification issue is also thought to be a stressor in what has been suggested as the return of the ocean to a primordial state, marked by a decrease in marine biodiversity and among other things, an increase in gelatinous marine organisms, most notably jellyfish. There are certainly a mix of reasons for the increase of jellies, but the decrease in shelled organisms helps release their gelatinous counterparts from competition for resources.

According to the Center for Ocean Solutions, other negative impacts include acidosis (a build-up of carbonic acid in marine organisms’ tissues leading to decreased immune response and other health consequences) and changes to the way sound travels underwater, resulting in the absorption of low frequency sounds which can inhibit communications and other uses of sound between sea creatures.

It’s yet another real and present danger we’re facing in today’s oceans.

Resources:

Chemtoons: Animations about how acids, bases, and buffers work

Center for Ocean Solutions: Decalcification

Center for Ocean Solutions: Ocean Acidification

Karl Grossman: The Jellyfish Revenge

NRDC – Ocean Acidification: The Other CO2 Problem

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