Study finds that warmer temperatures will alter fundamental chemistry
By Summit Voice
FRISCO — Scientists already know that a warming world is changing the timing of phytoplankton productivity in the ocean, with potential impacts up the food chain.
Now, a new study shows, rising ocean temperatures will affect plankton at more fundamental level, upsetting natural cycles of carbon dioxide, nitrogen and phosphorous. In the long run, oceans may be ruled by nitrogen-fixing cyanobacteria, the researchers concluded.
Besides providing food for many other species, plankton is also a key player in the carbon cycle, removing half of all CO2 from the atmosphere during photosynthesis and storing it deep under the sea — isolated from the atmosphere for centuries.
But water temperature has a direct impact on maintaining the delicate plankton ecosystem of our oceans. Global warming is likely to disrupt that balance and potentially drive a vicious cycle of climate change.
“Phytoplankton, including micro-algae, are responsible for half of the carbon dioxide that is naturally removed from the atmosphere,” said lead researcher Dr. Thomas Mock, of the University of East Anglia. “As well as being vital to climate control, it also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries so it is incredibly important for food security.
“Previous studies have shown that phytoplankton communities respond to global warming by changes in diversity and productivity. But with our study we show that warmer temperatures directly impact the chemical cycles in plankton, which has not been shown before.”
Collaborators from the University of Exeter, who are co-authors of this study, developed computer generated models to create a global ecosystem model that took into account world ocean temperatures, 1.5 million plankton DNA sequences taken from samples, and biochemical data.
“We found that temperature plays a critical role in driving the cycling of chemicals in marine micro-algae. It affects these reactions as much as nutrients and light, which was not known before,” said Dr Mock.
“Under warmer temperatures, marine micro-algae do not seem to produce as many ribosomes as under lower temperatures. Ribosomes join up the building blocks of proteins in cells. They are rich in phosphorous and if they are being reduced, this will produce higher ratios of nitrogen compared to phosphorous, increasing the demand for nitrogen in the oceans.
“This will eventually lead to a greater prevalence of blue-green algae called cyanobacteria which fix atmospheric nitrogen,” he explained.