DURHAM, N.C. A new Duke University-led study has documented dramatic, natural short-term increases in the acidity of a North Carolina estuary.
"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 I. Johnson, Arthur P. Kaupe Assistant Professor of Molecular Biology at Duke's Nicholas School of the Environment.
The short-term spikes in the acidity of the estuary were driven by changes in temperature, water flow, biological activity and other natural factors, the researchers said. And they are occurring in addition to the long-term acidification taking place in Earth's oceans as a result of human-caused climate change.
"For vulnerable coastal marine ecosystems, this may be adding insult to injury," said Johnson, who was lead author of the study.
When the effects of long-term ocean acidification and short-term natural variation combine, they can create "extreme events" which may be especially harmful to coastal marine life, he said.
The study was conducted at the Pivers Island Coastal Observatory at the Duke Marine Lab in Beaufort, N.C., as part of a long-term coastal monitoring program. Researchers collected seawater samples from Beaufort Inlet weekly for a year and on a daily and hourly basis for shorter periods to track changes in the water's pH and dissolved inorganic carbon on multiple time scales.
Numerous studies have shown that increasing amounts of atmospheric carbon dioxide from human sources are finding their way into the world's oceans. When the carbon dioxide dissolves in seawater, it reduces the water's pH and the ability of organisms to form calcium carbonate minerals that are the building blocks of many species' shells and
|Contact: Tim Lucas|