Taken-for-granted ocean carbon consumption highlights key role of individual species
It’s broadly understood that the world’s oceans play a crucial role in the global-scale cycling and exchange of carbon between Earth’s ecosystems and atmosphere. Now scientists at Scripps Institution of Oceanography at UC San Diego have taken a leap forward in understanding the microscopic underpinnings of these processes.
When phytoplankton use carbon dioxide to make new cells, a substantial portion of that cellular material is released into the sea as a buffet of edible molecules collectively called “dissolved organic carbon.” The majority of these molecules are eventually eaten by microscopic marine bacteria, used for energy, and recycled back into carbon dioxide as the bacteria exhale. The amount of carbon that remains as cell material determines the role that ocean biology plays in locking up atmospheric carbon dioxide in the ocean.
Thus, these “recycling” bacteria play an important role in regulating how much of the planet’s carbon dioxide is stored in the oceans. The detailed mechanisms of how the oceans contribute to this global carbon cycle at the microscopic scale, and which microbes have a leadership role in the breakdown process, are complex and convoluted problems to solve.
In a study published in the Proceedings of the National Academy of Sciences, Scripps scientists have pinpointed a bacterium that appears to play a dominant role in carbon consumption. Scripps’s Byron Pedler, Lihini Aluwihare, and Farooq Azam found that a single bacterium called Alteromonas could consume as much dissolved organic carbon as a diverse community of organisms.
“This was a surprising result,” said Pedler. “Because this pool of carbon is comprised of an extremely diverse set of molecules, we believed that many different microbes with complementary abilities would be required to breakdown this material, but it appears that individual species may be pulling more weight than others when it comes to carbon cycling.”
Pedler, a marine biology graduate student at Scripps, spent several years working with Scripps marine microbiologist Azam and chemical oceanographer Aluwihare in designing a system that would precisely measure carbon consumption by individual bacterial species. Because carbon in organic matter is essentially all around us, the most challenging part of conducting these experiments is avoiding contamination.
“Much of the carbon cycling in the ocean happens unseen to the naked eye, and it involves a complex mix of processes involving microbes and molecules,” said Azam, a distinguished professor of marine microbiology. “The complexity and challenge is not just that we can’t see it but that there’s an enormous number of different molecules involved. The consequences of these microbial interactions are critically important for the global carbon cycle, and for us.”
By demonstrating that key individual species within the ecosystem can play a disproportionally large role in carbon cycling, this study helps bring us a step closer to understanding the function these microbes play in larger questions of climate warming and increased acidity in the ocean.
“In order to predict how ecosystems will react when you heat up the planet or acidify the ocean, we first need to understand the mechanisms of everyday carbon cycling—who’s involved and how are they doing it?” said Pedler. “Now that we have this model organism that we know contributes to ocean carbon cycling, and a model experimental system to study the process, we can probe further to understand the biochemical and genetic requirements for the breakdown of this carbon pool in the ocean.”
While the new finding exposes the unexpected capability of a significant species in carbon cycling, the scientists say there is much more to the story since whole communities of microbes may interact together or live symbiotically in the microscopic ecosystems of the sea.
Pedler, Aluwihare, and Azam are now developing experiments to test other microbes and their individual abilities to consume carbon.
The study was supported by the Gordon and Betty Moore Foundation Marine Microbiology Initiative through grant GBMF2758 and the National Science Foundation.
# # #
The Gordon and Betty Moore Foundation believes in bold ideas that create enduring impact in the areas of science, environmental conservation and patient care. Intel co-founder Gordon and his wife Betty established the foundation to create positive change around the world and at home in the San Francisco Bay Area. Science looks for opportunities to transform–or even create–entire fields by investing in early- stage research, emerging fields and top research scientists. Our environmental conservation efforts promote sustainability, protect critical ecological systems and align conservation needs with human development. Patient care focuses on eliminating preventable harms and unnecessary healthcare costs through meaningful engagement of patients and their families in a supportive, redesigned healthcare system. Visit us at www.Moore.orgor follow @MooreScientific.
Mario Aguilera or Robert Monroe | Eurek Alert!
Northern bald ibises fit for their journey to Tuscany
21.08.2015 | Veterinärmedizinische Universität Wien
Boreal forests challenged by global change
21.08.2015 | International Institute for Applied Systems Analysis (IIASA)
Longer, more severe, and hotter droughts and a myriad of other threats, including diseases and more extensive and severe wildfires, are threatening to transform some of the world's temperate forests, a new study published in Science has found. Without informed management, some forests could convert to shrublands or grasslands within the coming decades.
"While we have been trying to manage for resilience of 20th century conditions, we realize now that we must prepare for transformations and attempt to ease...
A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.
The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...
A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).
Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...
In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.
These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...
Bacteria do not cease to amaze us with their survival strategies. A research team from the University of Basel's Biozentrum has now discovered how bacteria enter a sleep mode using a so-called FIC toxin. In the current issue of “Cell Reports”, the scientists describe the mechanism of action and also explain why their discovery provides new insights into the evolution of pathogens.
For many poisons there are antidotes which neutralize their toxic effect. Toxin-antitoxin systems in bacteria work in a similar manner: As long as a cell...
20.08.2015 | Event News
20.08.2015 | Event News
19.08.2015 | Event News
31.08.2015 | Awards Funding
31.08.2015 | Materials Sciences
31.08.2015 | Materials Sciences