Impact of ocean acidification on a key Arctic pelagic mollusc
As carbon dioxide (CO2) levels rise and global warming continues to rear it’s ugly head, disaster may be in store for some of our oceans key players. According to a study titled The Geological Record of Ocean Acidification published in Science this month, due to ocean acidification, the decline in pH caused by the rise of CO2 mainly due to anthropogenic sources, we may be headed into dangerous territory in comparison with historical carbon cycles.

Earth’s oceans gobble up approximately one quarter of the CO2 in the atmosphere. Carbonic acid is then formed, lowering the pH of seawater. Due to the drop in pH the concentration of the carbonate ion, which would normally be supersaturated in surface waters, is reduced. For calcifying organisms, organisms made of calcium carbonate, a decrease in carbonate ion concentrations could spell catastrophe. In the incidence that acidification directly affects calcifying organisms such as corals, molluscs and other creatures that produce their shells and plates from calcium carbonate, it could eventually upset the entire marine food chain.

In the study researchers looked to earth’s geological record for clues to what biotic responses might be based on record disruptions in carbon cycling and climate change, which were potentially caused by ocean acidification. In the past it has been challenging for researchers to determine future impacts of ocean acidification due to the limited sample period and the fact no existing oceanic crust or sediment is available for examination over 180 million years old.

Admittedly the study isn’t perfect. Researchers state in the paper “no past event perfectly parallels future projections in terms of disrupting the balance of ocean carbonate chemistry;” however, in the timespan of our geological record there are several events providing evidence regarding biotic responses in the incidence of carbon cycle disruption. It was concluded in the study that acidification levels seem to be headed for a maximum that we haven’t seen in the last 300 million years, which they call “unknown territory of marine ecosystem change.”