[Vision2020] NOAA: Ocean Acidification Accelerated in Nutrient-rich Areas: Marine Resources, Coastal Economies at Risk

[Ted Moffett]

Study finds that ocean acidification is accelerated in nutrient-rich areas
http://www.noaanews.noaa.gov/stories2012/20120924_oceanacidification.html
Marine resources, coastal economies put at risk

September 24, 2012

Carbon dioxide released from decaying algal blooms, combined with ongoing
increases in atmospheric carbon emissions, leads to increased levels of
ocean acidification, and places additional stress on marine resources and
the coastal economies that depend on them, according to a new study
published today.

Ocean acidification occurs when the ocean absorbs carbon dioxide from the
atmosphere or from the breakdown of organic matter, which then causes a
chemical reaction to make it more acidic. Species as diverse as scallops
and corals are vulnerable to ocean acidification, which can affect the
growth of their shells and skeletons.

Research by NOAA's William G. Sunda and Wei-jun Cai of the University of
Georgia points to the process of eutrophication - the production of excess
algae from increased nutrients, such as, nitrogen and phosphorus -- as a
large, often overlooked source of CO2 in coastal waters. When combined with
increasing CO2 in the atmosphere, the release of CO2 from decaying organic
matter is accelerating the acidification of coastal seawater.

The effects of ocean acidification on the nation's seafood industry are
seen in the Pacific Northwest oyster fishery. According to NOAA, ocean
acidification is affecting oyster shell growth and reproduction, putting
this multi-million dollar industry at risk. Annually, the Pacific Northwest
oyster fishery contributes $84 million to $111 million to the West Coast's
economy. According to an earlier NOAA study ocean acidification could put
more than 3,000 jobs in the region at risk.

Sunda and Cai used a new chemical model to predict the increase in acidity
of coastal waters over a range of salinities, temperatures and atmospheric
CO2 concentrations. They found that the combined interactive effects on
acidity from increasing CO2 in the atmosphere and CO2 released from the
breakdown of organic matter were quite complex, and varied with water
temperature, salinity and with atmospheric CO2.

"These interactions have important biological implications in a warming
world with increasing atmospheric CO2," said Sunda. "The combined effects
of the two acidification processes, along with increased nutrient loading
of nearshore waters, are reducing the time available to coastal managers to
adopt approaches to avoid or minimize harmful impacts to critical ecosystem
services such as fisheries and tourism."

Sunda and Cai found that, given current atmospheric CO2 concentrations and
projected CO2 released from organic matter decay, seawater acidity could
nearly double in waters with higher salinity and temperature, and could
rise as much as 12 times current levels in waters with lower salinity and
lower temperature.

These model predictions were verified with measured acidity data from the
northern Gulf of Mexico and the Baltic Sea, two eutrophic coastal systems
with large temperature and salinity differences, which experience
large-scale algal blooms. The observed and modeled increases in acidity
from eutrophication and algal decay are well within the range that can harm
marine organisms.

Funding support for the research came from the National Science Foundation,
NASA and NOAA. The study can be found in this month's edition of the
American Chemical Society's Environmental Science and Technology journal.

NOAA's mission is to understand and predict changes in the Earth's
environment, from the depths of the ocean to the surface of the sun, and to
conserve and manage our coastal and marine resources.

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Vision2020 Post: Ted Moffett
<http://www.noaa.gov/socialmedia>
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