Rising greenhouse gases profoundly impact microscopic marine life

[Henk Elegeert]

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http://www.eurekalert.org/pub_releases/2010-12/uosc-rgg122010.php
*Public release date: 20-Dec-2010*

Contact: James Leonard
jleonard3 at ucmerced.edu
209-228-4406
University of Southern California <http://www.usc.edu/>
Rising greenhouse gases profoundly impact microscopic marine life Study by
UC Merced marine biologist shows increased acidity of ocean water -- driven
by carbon dioxide emissions -- could fundamentally alter how nitrogen cycles
throughout the sea

MERCED, Calif. — The prolonged, extensive emission of greenhouse gases over
the next several decades could have significant impacts on ocean life,
according to a study by UC Merced marine biologist Michael Beman.

Increases in carbon dioxide emissions — exacerbated by the burning of fossil
fuels and other human activities — are making ocean water more acidic, and
Beman's study shows that the increased acidity will fundamentally alter the
way nitrogen cycles throughout the sea.

Because nitrogen is an important nutrient for all organisms, this could
ultimately have significant impacts for all forms of marine life.

"There is growing concern about this issue because human activities are
modifying ocean pH so rapidly," Beman said. "While we do not know what the
full effects of changing the nitrogen cycle will be, we performed
experiments all over the world and believe that these changes will be global
in extent."

Beman's study — funded by the National Science Foundation and co-authored by
a team of researchers from the University of Hawaii, University of Southern
California and the Bermuda Institute of Ocean Sciences — will be published
this week in the prestigious journal, *Proceedings of the National Academy
of Sciences* (PNAS). Beman conducted the studies while at the University of
Hawaii, before coming to UC Merced in 2009.

During the study, Beman and his coworkers decreased the pH level of ocean
water — making it more acidic — in six total experiments at four different
locations in the Atlantic and Pacific oceans: two near Hawaii, one off the
coast of Los Angeles, one near Bermuda and two in the Sargasso Sea southeast
of Bermuda.

In every instance, when the pH was decreased, the production of the oxidized
forms of nitrogen used by phytoplankton and other microorganisms also
decreased. That nitrogen is produced through the oxidation of ammonia in
seawater by microscopic organisms.

The results showed that when the pH of the water was decreased from 8.1 to
8.0 — roughly the decrease expected over the next 20 to 30 years — ammonia
oxidation rates decreased by an average of 21 percent over the six
experiments, with a minimum decrease of 3 percent and a maximum of 44
percent.

Such a reduction could lead to a substantial shift in the chemical form of
nitrogen supplied to phytoplankton, the single-celled aquatic "plants" that
form the base of the ocean's food web. The decrease in nitrogen would likely
favor smaller species of phytoplankton over larger ones, possibly creating a
domino effect throughout the food web.

This is an important step in furthering science's understanding of how
continued increases in greenhouse gas emissions will affect marine life on a
global scale and another example of UC Merced researchers addressing
society's most challenging problems.

"What makes ocean acidification such a challenging scientific and societal
issue is that we're engaged in a global, unreplicated experiment — one
that's difficult to study and has many unknown consequences," Beman said.

"Nevertheless, our results can be used to estimate the potential impacts of
acidification on the marine nitrogen cycle and on marine life in general.
These effects could be substantial and deserve additional study."

###

Co-authors on the PNAS paper were David A. Hutchins, Cheryl-Emiliane Chow,
Andrew L. King, Yuanyuan Feng and Jed A. Fuhrman of the University of
Southern California, Andreas Andersson and Nicholas R. Bates of the Bermuda
Institute of Ocean Sciences, and Brian N. Popp of the University of Hawaii.

UC Merced opened Sept. 5, 2005, as the 10th campus in the University of
California system and the first American research university of the 21st
century. The campus significantly expands access to the UC system for
students throughout the state, with a special mission to increase
college-going rates among students in the San Joaquin Valley. It also serves
as a major base of advanced research and as a stimulus to economic growth
and diversification throughout the region. Situated near Yosemite National
Park, the university is expected to grow rapidly, topping out at about
25,000 students within 30 years.

"

  ... lastige opstelling: '.. *could have* significant impacts on ocean life
..'.

Henk Elegeert

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