24 UCW NOVEMBER 11-17, 2009
WWW.UPANDCOMINGWEEKLY.COM
Troubled Waters
E/The Environmental Magazine
Why is the plankton in the oceans dying? And what does this mean for the health
of the oceans and marine life?.
— Marilynn Block, Portland, OR
As the lowest link on the marine food chain,
plankton — that tiny aquatic plant, animal and
bacterial matter floating throughout the world's
oceans — is a vital building block for life on earth.
Besides serving as a primary food source for many fish
and whales, plankton plays a crucial role in mitigating
global warming.
Indeed, the ocean is the world's largest "carbon
sink": As much as one-third of man-made CO2 emis-
sions are stored in the oceans and therefore do not
contribute to global warming. This is because its plant
component, phytoplankton (its animal component is
called zooplankton), pulls massive amounts of carbon
dioxide (CO2) out of the atmosphere as
it photosynthesizes.
But various environmental factors are taking their
toll on plankton the world over. The U.S. National
Oceanic and Atmospheric Administration (NOAA) re-
ported recently that marine phytoplankton is declining
across the oceans. Even Canadian cod fishermen are
noticing that the plankton-feeding fish they catch are
often nearly starving as a result of lack of this crucial
food source.
A 2007 study published in the scientific journal Nature found that human-caused
increase in CO2 pollution is altering the PH (acidity) levels in the oceans. This change
in chemistry is expected to have adverse effects on the entire ecosystem. More acidic
ocean water inhibits the ability of shell-forming marine organisms —
from plankton to mollusks to corals to form properly. Smaller and less healthy popula-
tions of plankton would be bad news for all the other creatures above it on the ocean's
food chain.
Higher water temperatures, also attributable to our fossil fuel addiction, can also
have a devastating effect on plankton. A recent report in
the Journal of the Marine Biological Association of the
United Kingdom noted that in the Adriatic Sea cooler
winter conditions — which are less frequent in a warmer
world — are needed for plankton production and nutri-
ent availability. Furthermore, warmer sea temperatures
can cause "blooms" of other sea life (such as happens
with algae), resulting in oxygen starvation in the water, a
condition that is devastating to plankton and other ma-
rine creatures and organisms.
In other situations, blooms of phytoplankton them-
selves — the tiny plants can gorge on the nutrients from
the run-off from farms and lawns on land — can lead
to oxygen starvation in the water. "The decomposition
of these multitudes of phytoplankton removes oxygen
from seawater, creating oxygen-poor 'dead zones' where
fish cannot live," reports Carly Buchwald, a researcher at
Woods Hole Oceanographic Institution.
Satellite imagery shows that these "dead zones" are
expanding. Some scientists are advocating iron fertiliza-
tion — the spreading of large amounts of iron across
the world's seas — to spur plankton growth. But others
worry that such tinkering with complex ecosystems could
have potentially harmful effects.
CONTACTS: Nature, www.nature.com; Journal of the Marine Biological
Association of the United Kingdom, www.journals.cambridge.org/
SEND YOUR ENVIRONMENTAL QUESTIONS TO: EarthTalk®, P.O. Box
5098, Westport, CT 06881; earthtalk@emagazine.com. Read past columns at: www.
emagazine.com/earthtalk/archives.php.
