Acidification Recorder Recovered From Antarctic Waters
October 19, 2012

Acidification Recorder Recovered From Antarctic Waters

April Flowers for - Your Universe Online

A National Science Foundation (NSF) supported research team retrieved data from a sensor in Antarctic waters that they hope will provide critical baseline data for the acidification, or chemical changes, in those remote seas.

Led by Gretchen Hofmann — professor of ecology, evolution and marine biology at the University of California, Santa Barbara (UCSB) — the all female team retrieved the sensor earlier this month following the harsh polar winter near McMurdo Station. McMurdo is the NSF's logistics hub in Antarctica.

The sensors were deployed by divers under the sea ice and left in place at the end of the 2011-2012 Antarctic research season. The sensor gathered data through the month of June, the height of winter in the Southern Hemisphere.However, due to the frigidity of the Antarctic waters, the sensor's battery eventually died, putting an end to data gathering.

On a positive note, the sensor's data will be the first of its kind about the relative acidity, or pH, of the waters in McMurdo Sound. Shipboard sensors have made some pH measurements, but the data logged by this instrument will be the first continuous pH record in a coastal region under sea ice in the winter. Combined with summer data, it will provide a more complete picture of seasonal variations in pH.

As increasing amounts of atmospheric carbon find their way into the oceans, global acidification is becoming more of a concern to scientists. An estimated 30 — 40 percent of carbon dioxide in the atmosphere dissolves into the world's water system, changing the chemical balance of the waters.

The change in chemical balance will affect marine life, making it more difficult for some species to create protective shells, to reproduce, and to grow. The impacts on individual species could then cascade to alter entire food chains or change how species interact, potentially altering entire ecosystems.

Gathering Antarctic pH data is crucial to understanding the current state of the ecosystem. This understanding will allow scientists to place future measurements in context. A pH baseline provides an important benchmark to begin testing whether certain species have the ability, both physiologically and genetically, to adapt to the projected change.

"One of our central research challenges is to forecast whether species will be able to adapt to a rapidly changing environment," Hofmann said in a press release. "It is critical to obtain current measurements of pH to help understand the environment that organisms will face in the future."

The Antarctic waters are biologically prolific and a complex ecosystem, with species previously unknown to the scientific community continuing to be found. Species that exist nowhere else, with adaptations to the extremely cold waters, can be found there. It's only recently, since the 1950's, that there has been any systematic study of the Southern Ocean, however.

Creating a pH record of the Antarctic region has been difficult for a number of reasons, most especially the lack of a durable sensor that is able to withstand the stresses put on equipment by Southern Ocean sea ice cover. The sensor Hofmann's team used is called SeaFET.

"Returning the first pH time series from such a remote and harsh environment is a true victory for all of the scientists involved. It represents a great example of technology developed through one NSF staff area, the [Directorate for Geosciences], enabling the research of another staff area, the [Office of Polar Programs]," said Todd Martz, of the Scripps Institution of Oceanography at the University of California, San Diego (UCSD) and one of the developers of SeaFET.