The tiny phytoplankton Emiliania huxleyi invisible to the eye, plays a disproportionate role in the development of carbon from the atmosphere and sequestration in the deep seas. But this role can change the sea water becomes warmer and more acidic, according to a research team from San Francisco State University.
In a study published this week in the journal Global Change Biology, SF State Assistant Professor of Biology Jonathon Stillman and his colleagues show how climate-driven changes in sources of nitrogen and carbon dioxide levels in the seawater could work together to Emiliania huxleyi less effective agent of carbon storage in the deep ocean, largest carbon sink in the world.
Modifications of this massive carbon sinks could have a critical effect on the global climate in the future, said Stillman, especially since atmospheric levels of carbon dioxide continue to rise sharply due to the burning of fossil fuels and other human activities.
While floating in the layers of the sun on the oceans, phytoplankton develop armor plates called coccoliths calcified developed. The coccoliths form a hard shell and heavy, finally sinks into the depths of the ocean. "About 80 percent of the inorganic carbon is trapped coccoliths of this kind," said Stillman.
Stillman and his colleagues wanted to find out how ocean acidification and changes in the marine nitrogen cycle, as well as signs of global warming may affect the development of the coccolith. So they raised more than 200 generations of Emiliania huxleyi in the laboratory by adjusting the concentration of carbon dioxide and nitrogen in a water bath type of phytoplankton sea.
They found that high levels of carbon dioxide, which makes the water more acidic, with a shift in the predominant nitrogen from ammonium nitrate "had a synergistic effect" of phytoplankton in the biology and growth.
In particular, the coccoliths formed under conditions of high carbon and high concentrations of ammonium were incomplete or empty, and contained less than the usual amount of inorganic carbon, the researchers noted.
"The relationship between inorganic to organic carbon is important," said Stillman. "As the inorganic carbon increases, it is more ballast to the hard shell that is flowing, and makes it more likely to be transported to the deep ocean. Without it, the more carbon can be recycled into Earth's atmosphere. "
"Our results suggest that in future there will be overall lower amounts of calcification and the amount generally less transport of carbon to the deep ocean," he added.
Emiliania huxleyi generally use nitrates to make proteins, but this form of nitrogen may be shorter supply of phytoplankton in the oceans of the world becomes warmer and more acidic, Stillman and his colleagues suggest. In the open ocean, nitrates are upwelling of deep water, but a thickening layer of warm surface water that could inhibit recovery. At the same time to encourage warmer temperatures the bacteria that convert nitrogen recycled from the surface and atmosphere of ammonia and acidification inhibits the bacteria that convert ammonium to nitrate.
"It is likely that in future the ocean surface contain more ammonium", where the phytoplankton absorbs rather than nitrate, Stillman suggested. "Metabolizable Ammonium nitrate nitrogen as compared requires different biochemical components that influence how their coccoliths cells. They survive very well, but their biology vary accordingly."
The study by Stillman and his colleagues were the first to study the effects interspersed with ocean acidification and changes in nitrogen on phytoplankton Emiliania huxleyi. It is also one of the first studies to observe these effects continuously over a long, "so that the phytoplankton response is probably what we see in the sea itself," said Stillman.
Stéphane Lefebrve, his fellow student of SF State has developed experiments for the study, said he now is looking for genes that phytoplankton "will help us build the genetic model responses of carbon dioxide and a source of nitrogen"
0 comments:
Post a Comment