The frequency at which droplets emerge is controlled by an acoustic trigger, which can be tuned so that each droplet containing a protein or virus meets an incoming pulse of x-rays. |
Might
a penguin’s next meal be affected by the exhaust from your tailpipe?
The answer may be yes, when you add your exhaust fumes to the total
amount of carbon dioxide lofted into the atmosphere by humans since the
industrial revolution. One-third of that carbon dioxide is absorbed by
the world’s oceans, making them more acidic and affecting marine life.
A
University of California Santa Barbara marine scientist and a team of 18 other researchers
have reported results of the broadest worldwide study of ocean
acidification to date. Acidification is known to be a direct result of
the increasing amount of greenhouse gas emissions. The scientists used
sensors developed at Scripps Institution of Oceanography at University of California San Diego
to measure the acidity of 15 ocean locations, including seawater in the
Antarctic, and in temperate and tropical waters.
As
oceans become more acidic, with a lower pH, marine organisms are
stressed and entire ecosystems are affected, according to the
scientists. Gretchen E. Hofmann, an eco-physiologist and professor in
UCSB’s Department of Ecology, Evolution & Marine Biology, is lead
author of the recent article in PLoS ONE that describes the research.
“We
were able to illustrate how parts of the world’s oceans currently have
different pH, and thus how they might respond to climate changes in the
future,” said Hofmann. “The sensors allowed us to capture that.” The
sensors recorded at least 30 days of continuous pH values in each area
of the study.
Since
the beginning of the industrial revolution, human activities have
accelerated the release of carbon dioxide into the atmosphere as carbon
dioxide mixes with water. The two molecules combine to become carbonic
acid, making seawater more acidic. As billions of molecules combine and
go through this process, the overall pH of the oceans decreases, causing
ocean acidification.
Acidification
limits the amount of carbonate forms that are needed by marine
invertebrates, such as coral, urchins, snails, and shellfish, to make
their skeletons. As the concentration of carbonates decreases in
acidified water, it is harder to make a shell. And, the structures of
some organisms may dissolve when water chemistry becomes too
unfavorable.
“The
emerging pH data from sensors allows us to design lab experiments that
have a present-day environmental context,” said Hofmann. “The
experiments will allow us to see how organisms are adapted now, and how
they might respond to climate change in the future.”
Hofmann
researched the Antarctic, where she has worked extensively, as well as
an area of coral reefs around the South Pacific island of Moorea, where
UCSB has a Long-Term Ecological Research (LTER) project. She also
studied the coastal waters of Santa Barbara, in conjunction with UCSB’s
Santa Barbara Coastal LTER. The research team provided 30 days of pH
data from other ocean areas around the world.
The
researchers found that, in some places such as Antarctica and the Line
Islands of the South Pacific, the range of pH variance is much more
limited than in areas of the California coast that are subject to large
vertical movements of water, known as upwellings. In some of the study
areas, the researchers found that the decrease in seawater pH being
caused by greenhouse gas emissions is still within the bounds of natural
pH fluctuation. Other areas already experience daily acidity levels
that scientists had expected would only be reached at the end of this
century.
“This
study is important for identifying the complexity of the ocean
acidification problem around the globe,” said co-author Jennifer Smith, a
marine biologist with Scripps. “Our data show such huge variability in
seawater pH, both within and across marine ecosystems, making global
predictions of the impacts of ocean acidification a big challenge.”
Todd
Martz, a marine chemistry researcher at Scripps, developed the sensor.
“When I arrived at Scripps, we re-engineered my prototype design, and
since then I have not been able to keep up with all of the requests for
sensors,” said Martz. “Because every sensor used in this study was built
at Scripps, I was in a unique position to assimilate a number of
datasets, collected independently by researchers who otherwise would not
have been in communication with each other. Each time someone deployed a
sensor, they would send me the data, and eventually it became clear
that a synthesis should be done to cross-compare this diverse collection
of measurements.”
Hoffman worked with Martz to put together the research team to create that synthesis.
The
team noted that the Scripps sensors, called “SeaFET” and “SeapHOx,”
allow researchers to continuously and autonomously monitor pH from
remote parts of the world, providing important baselines from which
scientists can monitor future changes caused by ocean acidification.
Despite
surveying 15 different ocean regions, the authors noted that they only
made observations on coastal surface oceans, and that more study is
needed in deeper ocean regions farther away from land.
Hofmann
is the director of the Center for the Study of Ocean Acidification and
Ocean Change, a UC multi-campus initiative. Hofmann participated in
writing a report on ocean acidification while on the National Research
Council’s Ocean Acidification Committee, and she is currently
participating as a lead author on the National Climate Assessment.
Hofmann is a member of the National Science Foundation’s Office of Polar
Programs Advisory Panel, and she is an Aldo Leopold Fellow.
In
addition to Hofmann, Martz, and Smith, co-authors include Emily B.
Rivest and Pauline Yu of UCSB; Uwe Send, Lisa Levin, Yuichiro Takeshita,
Nichole N. Price, Brittany Peterson, and Christina A. Frieder of
Scripps; Paul Matson and Kenneth Johnson of the Monterey Bay Aquarium
Research Institute; Fiorenza Micheli and Kristy Kroeker of Stanford
University; Adina Paytan and Elizabeth Derse Crook of UC Santa Cruz; and
Maria Cristina Gambi of Stazione Zoologica Anton Dohrn in Naples,
Italy.
Funding
for instrument development and related field work came from several
sources, including the National Science Foundation, the David and Lucile
Packard Foundation, the University of California, the Gordon and Betty
Moore Foundation, the Nature Conservancy, the WWW Foundation, Scott and
Karin Wilson, the Rhodes family, and NOAA.
