Rising CO2, Ocean Acidification, and
Their Impacts on Marine Microbes

micrograph of marine microbes

Image by U. Sacchi and M. Montresor

Expert Meeting organised by the Plymouth Marine Laboratory (PML) and the Center for Microbial Oceanography: Research and Education (C-MORE) at the Keoni Auditorium, East-West Center, the University of Hawai“i at Mānoa • 24 to 26 February 2009

The Plymouth Marine Laboratory (PML), UK and the Center for Microbial Oceanography: Research and Education (C-MORE) at the University of Hawai‘i cordially invite you to attend our symposium on Tuesday 24 February 2009 at the East-West Center on the University of Hawai‘i’s at Manoa campus. The organizing committee, Ian Joint (PML), Chair, Scott Doney (Woods Hole Oceanographic Institution), and Dave Karl (C-MORE) value your participation.

One of the least-understood consequences of increasing carbon dioxide concentrations in the atmosphere is that the oceans are becoming more acidic.

This is because CO2 in the air dissolves in seawater to form carbonic acid — a weak acid that makes the oceans slightly more acidic. The rate of change is extremely rapid and it is expected that by the end of this century, the oceans will be more acidic than they have been for more than 20 million years.

Over geological time scales, the pH of the seas has changed significantly in response to variations in atmospheric CO2. Indeed, the ocean has in the past been more acidic than we expect it to become over the coming decades. But what is different this time is the speed of change. Ecosystems have proved their ability to accommodate change when it is gradual, usually over hundreds of thousands of years. We do not know how well the marine ecosystem will adapt to changes that will occur over decades.

Microbes are the most important organisms in the sea. In contrast to the land, where plants are large and long-lived, in the seas most of the primary production comes from microscopic algae, or phytoplankton. These have tiny biomass and their generations last only days. The productivity of this phytoplankton depends in turn on bacteria and archaea to regenerate nutrients. So it was a priority to determine how marine microbes would respond to a high-CO2 world.

Microbes control biogeochemical cycles and keep the planet habitable. This means we need to know how microbial populations will respond to rapid climate change. We need to do experiments to understand how marine microbes will respond to pH change.

Such experiments will be complex because pH varies naturally over the course of a year. When phytoplankton populations begin to grow in the spring they consume CO2 that is dissolved in seawater. The result is that pH increases for a period of a few weeks. The dissolved CO2 gradually increases as a result of bacterial activity and the pH declines to a more typical values. In a high CO2 world, this seasonal variability will still exist but the microbial populations will be exposed to a different range of pH values than in the present day.

In this symposium, world experts in the field will give presentations on the research that they are doing to understand how marine microbes will adapt to the new conditions that will occur in the coming century.

Graphic of Station ALOHA curve This all-day symposium is the first part of a 3-day workshop to assess the impacts of CO2 and ocean acidification on the community structure, metabolism and ecosystem services provided by marine microbes. An international group of experts will provide up-to-date information on the probable future impacts of ocean climate change. The morning session will include five invited plenary talks by leading authorities in a variety of relevant topics. The afternoon session will include a series of shorter, more specialized presentations.

Lunch will be provided. Please RSVP with Sharon Sakamoto by Monday 16 February to reserve a space.


Funding for the symposium and the workshop is provided by the Gordon and Betty Moore Foundation, the Agouron Institute, and the National Science Foundation.

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