Research trip to the Antarctic: Probing ocean acidification

Science journalist Jane Qiu has now reached the Palmer ecological research station on the Antarctic Peninsula, joining researchers investigating how climate change has affected the region in recent decades. Please check back for her dispatches from the bottom of the world.

The Palmer ecological research station is buzzing with excitement. As the morning sunlight pierces an overcast sky and turns the placid sea silver, the researchers are busy loading the inflatable boats in preparation for a water-collection campaign that will mobilize many in this small research community on the Western Antarctic Peninsula.

This marks the start of an ambitious interdisciplinary project to assess the effect on the Antarctic marine ecosystem of increased carbon dioxide levels in the atmosphere. The researchers will sail to Station B, a patch of water roughly 1.5 kilometres from the dock, and pump up 650 litres of seawater from the ocean.

They will ‘incubate’ the water – along with an assemblage of organisms, from viruses to microscopic plants called phytoplankton to small marine animals from this coastal environment – under three carbon dioxide conditions: the pre-industrial level (280ppm or parts per million), the current level (385ppm), and the maximum level projected for the end of the 21st century (750ppm), according to the Intergovernmental Panel on Climate Change.

“The main question for us is how an increase in carbon dioxide changes phytoplankton assemblages in the Western Antarctic Peninsula and how that affects other components of the ecosystem such as zooplankton, bacteria and viruses,” says Grace Saba, an ecologist at Rutgers University in New Brunswick, New Jersey.

The ocean becomes more acidic when it absorbs more carbon dioxide from the atmosphere. “We know carbon dioxide is increasing and the pH is lowering in the ocean, but we cannot predict what this means to the Antarctic ecosystem,” says Alex Culley, a marine virologist at the University of Hawaii at Mānoa. It’s important to simulate what will occur so we have a better understanding of how the ecosystem will respond to climate change, he says.

After various periods of incubation, some researchers will assess how well phytoplankton – the starting point of the aquatic food chain – have grown and what types of plants are present in waters under different carbon dioxide levels. They will also be looking at how these conditions could affect carbon update, photosynthesis and nutrient recycling.

Other researchers will be studying how phytoplankton grown at different carbon dioxide levels could affect Antarctic krill – small, shrimp-like creatures that are the major food resource for penguins, whales and seals in the Southern Ocean – as well as productivity and genetic diversity of marine bacteria and viruses.

Ultimately, the researchers will compare the results from the Western Antarctic Peninsula – where the winter mean temperature has increased by 6°C and the ice season has shortened by nearly 90 days in the last 50 years – with those from other parts of the Antarctic, say the Ross Sea, that are still relatively stable.

“We hope to see whether ecosystem responses are different at different parts of the Antarctic and identify the key players that drive those changes,” says Oscar Schofield, an oceanographer also at Rutgers, who leads the study.

Jane Qiu, The Great Beyond, 7 December 2010. Article.

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