Dramatic Spikes in Ocean Acidity May Drastically Impact Coastal Ecosystems

As ocean acidity becomes more of an issue with increased levels of carbon dioxide in our atmosphere, scientists are taking a closer look at the phenomenon. Now, researchers have found dramatic and natural short-term increases in the acidity of a North Carolina estuary.

The researchers monitored this estuary as part of a long-term coastal monitoring program. The scientists collected seawater samples from Beaufort Inlet weekly for a year and on a daily and hourly basis for shorter periods in order to track changes in the water's pH and dissolved inorganic carbon on multiple time scales. In the end, they found that a wide range of natural variables, including changes in temperature, algal production and respiration, and water movement caused by tides and storms, triggered sharp spikes in the inlet's acidity. While some changes occurred over the course of a season, others occurred on a daily or even on an hourly basis.

"The natural short-term variability in acidity we observed over the course of one year exceeds 100-year global predictions for the ocean as a whole and may already be exerting added pressure on some of the estuary's organisms, particularly shelled organisms that are especially susceptible to changes in pH," said Zackary Johnson, one of the researchers, in a news release. "For vulnerable coastal marine ecosystems, this may be adding insult to injury."

In fact, when the effects of long-term ocean acidification combine with short-term natural variation, they can create "extreme events" which may be especially harmful to coastal marine life. If current trends continue, it's possible that the mean ocean pH will decrease by about .2 units over the next 50 years. This could have severe effects on ocean ecosystems and organisms.

"We may see significant changes in biological processes such as primary production," said Dana Hunt, one of the researchers, in a news release. "Some organisms, such as phytoplankton, may benefit. Many others, including shelled organisms and corals, will not."

The findings don't just have implications for this estuary, either. It also could have implications for other coastal regions. As pH increases globally, local rises in pH could combine and exacerbate issues. This could be extremely damaging to coastal ecosystems.

The findings are published in the journal PLOS One.