Ocean Acidity Rivals Climate Change As Environmental Threat
Posted By: Kat J. McAlpine 
Smithsonain Magazine
July 18, 2012
http://blogs.smithsonianmag.com/science/2012/07/ocean-acidity-rivals-climate-change-as-environmental-threat/

Anthropogenic emissions of greenhouse gases are
increasing ocean acidity at an alarming pace. A new
study offers hope that some species may survive as a
result of rapid adaptation. 

Since the Industrial Revolution, ocean acidity has risen
by 30 percent as a direct result of fossil-fuel burning
and deforestation. And within the last 50 years, human
industry has caused the world's oceans to experience a
sharp increase in acidity that rivals levels seen when
ancient carbon cycles triggered mass extinctions, which
took out more than 90 percent of the oceans' species and
more than 75 percent of terrestrial species.

Rising ocean acidity is now considered to be just as
much of a formidable threat to the health of Earth's
environment as the atmospheric climate changes brought
on by pumping out greenhouse gases. Scientists are now
trying to understand what that means for the future
survival of marine and terrestrial organisms.

In June, ScienceNOW reported that out of the 35 billion
metric tons of carbon dioxide released annually through
fossil fuel use, one-third of those emissions diffuse
into the surface layer of the ocean. The effects those
emissions will have on the biosphere is sobering, as
rising ocean acidity will completely upset the balance
of marine life in the world's oceans and will
subsequently affect humans and animals who benefit from
the oceans' food resources.

The damage to marine life is due in large part to the
fact that higher acidity dissolves naturally-occurring
calcium carbonate that many marine species-including
plankton, sea urchins, shellfish and coral-use to
construct their shells and external skeletons. Studies
conducted off Arctic regions have shown that the
combination of melting sea ice, atmospheric carbon
dioxide and subsequently hotter, CO2-saturated surface
waters has led to the undersaturation of calcium
carbonate in ocean waters. The reduction in the amount
of calcium carbonate in the ocean spells out disaster
for the organisms that rely on those nutrients to build
their protective shells and body structures.

The link between ocean acidity and calcium carbonate is
a directly inverse relationship, which allows scientists
to use the oceans' calcium carbonate saturation levels
to measure just how acidic the waters are. In a study by
the University of Hawaii at Manoa published earlier this
year, researchers calculated that the level of calcium
carbonate saturation in the world's oceans has fallen
faster in the last 200 years than has been seen in the
last 21,000 years-signaling an extraordinary rise in
ocean acidity to levels higher than would ever occur
naturally. 

Coral reef ecosystems, such as Palmyra Atoll, located
1,000 miles south of Hawaii, will dwindle as adequately
nutrient-rich waters will be diminished to five percent
of the world's oceans. Photo courtesy of Flickr user
USFWS Pacific.

The authors of the study continued on to say that
currently only 50 percent of the world's ocean waters
are saturated with enough calcium carbonate to support
coral reef growth and maintenance, but by 2100, that
proportion is expected to drop to a mere five percent,
putting most of the world's beautiful and diverse coral
reef habitats in danger.

In the face of so much mounting and discouraging
evidence that the oceans are on a trajectory toward
irreparable marine life damage, a new study offers hope
that certain species may be able to adapt quick enough
to keep pace with the changing make-up of Earth's
waters.

In a study published last week in the journal Nature
Climate Change, researchers from the ARC Center of
Excellence for Coral Reef Studies found that baby
clownfish (Amphiprion melanopus) are able to cope with
increased acidity if their parents also lived in higher
acidic water, a remarkable finding after a study
conducted last year on another clownfish species
(Amphiprion percula) suggested acidic waters reduced the
fish's sense of smell, making it likely for the fish to
mistakenly swim toward predators.

But the new study will require further research to
determine whether or not the adaptive abilities of the
clownfish are also present in more environmentally-
sensitive marine species.

While the news that at least some baby fish may be able
to adapt to changes provides optimism, there is still
much to learn about the process. It is unclear through
what mechanism clownfish are able to pass along this
trait to their offspring so quickly, evolutionarily
speaking. Organisms capable of generation-to-generation
adaptations could have an advantage in the coming
decades, as anthropogenic emissions push Earth to non-
natural extremes and place new stresses on the
biosphere.

___________________________________________

Portside aims to provide material of interest to people
on the left that will help them to interpret the world
and to change it.

Submit via email: [log in to unmask]

Submit via the Web: http://portside.org/submittous3

Frequently asked questions: http://portside.org/faq

Sub/Unsub: http://portside.org/subscribe-and-unsubscribe

Search Portside archives: http://portside.org/archive

Contribute to Portside: https://portside.org/donate