New study suggests ocean's plankton under greater threat from acidification

In summary: 
  • Ocean acidification could pose a bigger threat to marine plankton than previously thought according to a new paper by an international research team from the UK and Australia
  • The team, including Dr Mark Baird from UTS, is concerned some of the most critical organisms to the Earth's biogeochemical cycles will be disproportionately affected

New research from the UK and Australia suggests that changes in the ocean's chemistry, as a result of global warming, could threaten organisms such as marine plankton to a greater extent than previously thought.

Dr Mark Baird, a Research Fellow with The Plant Functional Biology and Climate Change Cluster (C3) is a member of the international team researching ocean acidification and the changes it causes in the pH levels at the exterior surface of plankton.

The work is led by Professor Kevin Flynn of Swansea University's Centre for Sustainable Aquatic Research, in collaboration with colleagues in the UK and Professor John Beardall from Monash University.

Professor Flynn said, "Human impact on the environment means carbon dioxide is dissolving in the ocean, which is naturally alkaline, and causing a decrease in seawater pH levels – an event termed ocean acidification."

He added that although ocean acidity could double from its present value by 2100 it was unclear how the growth of plankton would respond.

"However, given the important role these organisms play in the Earth's biogeochemical cycles, the impact that ocean acidification-induced changes in the chemical composition of seawater will have on plankton is a major concern," Professor Flynn said.

The work indicates that experimental approaches used in most previous studies, such as shaking of samples, disturbs natural plankton communities and thus affects pH gradients next to cells.

Dr Mark Barid, picture by Marea MartlewDr Mark Baird, picture by Marea Martlew

Dr Mark Baird said, "Numerical models allow us to isolate one phenomenon, such as how cell size alters plankton susceptibility to ocean acidification. This is difficult to do using laboratory experiments."

However, using simulations, the team has presented and discussed mechanisms by which many marine plankton will experience a substantially more acidic environment than currently suggested by ocean acidification scenarios – experiencing pH conditions which are completely outside their recent historical range.

Their results suggest that changes in the pH at the cell surface of plankton could adversely affect cellular equilibrium, leading to poor growth if not death. 

Importantly, the team's work suggests that some of the most critical organisms to the Earth's biogeochemical cycles, such as planktonic calcifiers (coccolithophorids and forams), will be disproportionately affected by this mechanism.

These changes could represent a powerful driving force, shaping the composition of plankton communities of the future ocean.

"The implications of our research are profound," said Professor Flynn. "They suggest scope for a more serious impact of oceanic acidification upon marine plankton than previously thought."

Professor Beardall added, "In Australia we propose to apply this research to understand the synergistic effects of ocean acidification and other aspects of climate change on key Australian phytoplankton species."

The team's paper, Changes in pH at the exterior surface of plankton with ocean acidification, is published online by leading journal Nature Climate Change.

The full paper can be read at this link until July 18.

The research was primarily funded by the Natural Environment Research Council.

Ocean Acidification is now irreversible... at least on timescales of at least... TENS of THOUSANDS of years...

Even with stabilisation of atmospheric CO2 at 450 ppm, Ocean Acidification will have profound impacts (death and extinction) on many marine systems.

LARGE and rapid reductions of global CO2 emissions are needed globally by at LEAST 50% by 2050.

Analysis of past events in Earth's geologic history suggests that chemical recovery (normal pH for LIFE in the Ocean) will take TENS of THOUSANDS of years - while the recovery of ecosystem function and biological diversity (LIFE AS WE KNOW IT) can take much longer. (MILLIONS OF YEARS)

..:: "Every day, 70 MILLION TONS of CO2 are released into Earth's atmosphere. ( remaining in the atmosphere for thousands of years )

..:: "Every day, 20 MILLION TONS of that CO2 are absorbed into the OCEANS, thereby increasing the overall ACIDITY of the OCEANS.

By 2100, Ocean acidity will increase another 150 to 200 hundred percent.

This is a dramatic change in the acidity of the oceans. And it has a serious impact on our ocean ecosystems; in particular, it has an impact on any species of calcifying organism that produces a calcium carbonate SHELL.


..:: "These are changes that are occurring far too fast for the oceans to correct naturally, said Dr Richard Feely with the US National Oceanic and Atmospheric Administration (NOAA)

..:: "Fifty-five million years ago when we had an event like this (and that took over 10,000 years to occur), it took the oceans over 125,000 years to recover, just to get the chemistry back to normal," he told BBC News.

..:: "It took two to 10 million years for the organisms to re-evolve, to get back into a normal situation.

..:: "So what we do over the next 100 years will have implications for ocean ecosystems from tens of thousands to millions of years. That's the implication of what we're doing to the oceans right now."



Thanks for sharing this information and links on ocean acidification.

Hi Larry,

Thanks for your comments. The predictions for changing pH of the oceans are alarming. While we are thankful for the physical process of the ocean absorbing about 1/3 of the global emissions, the decrease in pH will have profound biological impacts.

It is probably most instructive to think of winners and losers. Calcifying microalgae and coral reef calcifiers are most at risk. Should they diminish, non-calcifying photosynthetic organisms will no doubt occupy part of their ecological niche, but for what change to the ecosystem structure?

When you add ocean acidification to other likely biological impacts of climate change, mitigation of climate change doesn't seem so expensive ...

Kind regards, Mark