Dramatic variability of the carbonate system at a temperate coastal ocean site (Beaufort, North Carolina, USA) is regulated by physical and biogeochemical processes on multiple timescales.


Increasing atmospheric carbon dioxide (CO2) from anthropogenic sources is acidifying marine environments resulting in potentially dramatic consequences for the physical, chemical and biological functioning of these ecosystems. If current trends continue, mean ocean pH is expected to decrease by ~0.2 units over the next ~50 years. Yet, there is also substantial temporal variability in pH and other carbon system parameters in the ocean resulting in regions that already experience change that exceeds long-term projected trends in pH. This points to short-term dynamics as an important layer of complexity on top of long-term trends. Thus, in order to predict future climate change impacts, there is a critical need to characterize the natural range and dynamics of the marine carbonate system and the mechanisms responsible for observed variability. Here, we present pH and dissolved inorganic carbon (DIC) at time intervals spanning 1 hour to >1 year from a dynamic, coastal, temperate marine system (Beaufort Inlet, Beaufort NC USA) to characterize the carbonate system at multiple time scales. Daily and seasonal variation of the carbonate system is largely driven by temperature, alkalinity and the balance between primary production and respiration, but high frequency change (hours to days) is further influenced by water mass movement (e.g. tides) and stochastic events (e.g. storms). Both annual (~0.3 units) and diurnal (~0.1 units) variability in coastal ocean acidity are similar in magnitude to 50 year projections of ocean acidity associated with increasing atmospheric CO2. The environmental variables driving these changes highlight the importance of characterizing the complete carbonate system rather than just pH. Short-term dynamics of ocean carbon parameters may already exert significant pressure on some coastal marine ecosystems with implications for ecology, biogeochemistry and evolution and this shorter term variability layers additive effects and complexity, including extreme values, on top of long-term trends in ocean acidification.





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Publication Info

Johnson, Zackary I, Benjamin J Wheeler, Sara K Blinebry, Christina M Carlson, Christopher S Ward and Dana E Hunt (2013). Dramatic variability of the carbonate system at a temperate coastal ocean site (Beaufort, North Carolina, USA) is regulated by physical and biogeochemical processes on multiple timescales. PLoS One, 8(12). p. e85117. 10.1371/journal.pone.0085117 Retrieved from https://hdl.handle.net/10161/10666.

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Zackary Johnson

Juli Plant Grainger Associate Professor of Biological Oceanography and Marine Biotechnology

Our group broadly studies the abundance, diversity and activity of marine microbes. We are biological oceanographers, marine molecular ecologists, marine microbiologists and biogeochemists.  Our research focuses on the marine cyanobacteria Prochlorococcus, the most abundant phytoplankton in the open oceans and an excellent model marine microbe, as well as the biotechnological applications of marine microalgae.  We are at the Marine Laboratory as part of the Nicholas School of the Environment at Duke University.


Dana E. Hunt

Associate Professor of Microbial Ecology

My research focus is on understanding the ecology of microbes through examination of their genes and lifestyles. Bacteria are the most diverse organisms on earth and play a pivotal role in planetary cycling of nutrients and energy. Yet, we have a poor understanding of the factors that drive their diversity and dynamics in the environment. The lab's emphasis is on studying bacterial interactions with the environment at the appropriate temporal and spatial scale including the effect of temperature changes on bacterial populations and bacterial interactions with other organisms. Another area of active research is the response and adaptation of bacteria to emerging pollutants such as antibiotics and nanoparticles.

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