A Warm, Acidic Bath: How Will Changes in the Ocean Impact Coccolithophores?

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Phytoplankton bloom in the Barents Sea. These tiny organisms are vital to the ocean's carbon cycles. Image by NASA.

Phytoplankton bloom in the Barents Sea. These tiny organisms are vital to the ocean’s carbon cycles. Image courtesy of NASA

Climate Change: Interacting Variables Mean That the Future is Uncertain

Does this study mean that warmer oceans will have a greater ability to sequester carbon? Not necessarily. Stillman tells us that there are still more variables to explore. Plants need nitrogen to grow, and scientists anticipate that future changes in the oceans’ will mean that phytoplankton will get more of their nitrogen from ammonium and not nitrate.

In their experiments, the researchers have discovered that this shift reduces the ability of coccolithophores to create their shells.

Phytoplankton: The Clues Are in the Genes

Stillman says that this study was one of the first to study the gene expression of coccolithophores, and what they found was intriguing. Changes in temperature and carbon dioxide levels didn’t necessarily turn off the genes that control calcification. They did change the genes that likely control processes that regulate the binding of calcium. This gives scientists additional clues as to what to look for when they’re studying the shell-creating abilities of these tiny organisms.

Carbon Cycle, Phytoplankton, and Climate Change

The world’s oceans absorb huge amounts of carbon and store it deep in the ocean, where it’s out of the atmospheric carbon cycle for thousands of years. This is an enormous and largely invisible ecological service, and it’s unclear how future changes in the ocean and the atmosphere will change the oceans’ ability to store this carbon.

Will the tiny plants in the world’s oceans continue to sequester huge amounts of carbon, or will their ability to sink this carbon to the deep ocean be compromised? Will they become even more robust, growing thick shells and storing atmospheric carbon in the deep? What the San Francisco studies show is that the interactions between marine organisms, temperature, nutrient levels, and acidity are very complex. There’s no easy answer to the questions about what will happen to the oceans due to our global experiment with the climate.

Resources

Ina Benner, Rachel E. Diner, Stephane C. Lefebvre, Dian Li, Tomoko Komada, Edward J. Carpenter, and Jonathon H. Stillman. Emiliania huxleyi increases calcification but not expression of calcification-related genes in long-term exposure to elevated temperature and pCO2. (2013). Philosophical Transactions of the Royal Society, Biological Sciences. DOI: 10.1098/rstb.2013.0049. Accessed September 3, 2013.

Fisheries and Oceans Canada. Ocean Acidification. Accessed September 3, 2013.

NASA. What is a Coccolithophore? Accessed September 3, 2013.

Stillman, J. Personal Interview. August 2013.

US EPA. Future Climate Change. Accessed September 3, 2013.

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