|
 You
know that green scum creeping across the surface of your local public
water reservoir? Or maybe it’s choking out a favorite fishing spot or
livestock watering hole. It’s probably cyanobacteria – blue-green algae
– and, according to a paper in the April 4 issue of the journal
Science, it relishes the weather extremes that accompany global
warming.
Dr. Hans Paerl, co-author of the Science paper and Kenan
University Distinguished professor at the Institute of Marine Sciences
and in the School of Public Health's Department of Environmental
Sciences and Engineering, calls the algae the “cockroach of lakes.”
It’s everywhere and it’s hard to exterminate – but when the sun comes
up, it doesn’t scurry to a corner. It’s still there, and it’s growing,
as thick as 3 feet in some areas.
The algae has been linked to digestive, neurological and skin
diseases and fatal liver disease in humans. It costs municipal water
systems many millions of dollars to treat in the United States alone.
And though it’s more prevalent in developing countries, it grows on key
bodies of water across the world, including Lake Victoria in Africa,
the Baltic Sea, Lake Erie and bays of the Great Lakes, Florida’s Lake
Okeechobee and in the main reservoir for Raleigh, N.C.
“This is a worldwide problem,” said Paerl.
“It’s long been known that nutrient runoff contributes to
cyanobacterial growth. Now scientists can factor in temperature and
global warming,” said Paerl, who, with professor Jef Huisman from the
University of Amsterdam, the Netherlands, explains the new realization
in Science paper.
“As temperatures rise, waters are more amenable to blooms,” Paerl said.
The algae also thrive in wet, soggy ground in areas experiencing
periodic floods, like the U.S. Midwest. And in a drought, like the
Southeastern United States is experiencing now, other algae and aquatic
organisms die off, while cyanobacteria thrive, waiting to explode.
Warmer weather has also created longer growing seasons, and it’s
enabled cyanobacteria to grow in northern waters previously too cold
for their survival. Species first found in southern Europe in the 1930s
now form blooms in northern Germany, and a Florida species now grows in
the Southeastern U.S. Others have appeared recently places as far north
as Montana and throughout Canada.
Fish and other aquatic animals and plants stand little chance against
cyanobacteria. The algae crowds the surface water, shading out plants –
fish food – below. The fish generally avoid cyanobacteria, so they’re
left without food. And when the algae die they sink to the bottom where
their decomposition can lead to extensive depletion of oxygen.
These cyanobacteria – blue-green algae – were the first plants on earth to produce oxygen.
“It’s ironic,” Paerl said. “Without cyanobacteria, we wouldn’t be here.
Animal life needed the oxygen the algae produced.” Now, however, it
threatens the health and livelihood of people who depend on infested
waters for drinking water or income from fishing and recreational use.
These algae that were first on the scene, Paerl predicts, will be the last to go ... right after the cockroaches.
# # #
Note: Paerl can be reached at (252) 241-8656 or
hans_paerl@unc.edu.
Visit his Web site at http://www.unc.edu/ims/paerllab/.
For photos, visit: http://uncnews.unc.edu/news/science-and-technology/algalimages.html.
School of Public Health contact: Ramona DuBose, director of communications, (919) 966-7467 or ramona_dubose@unc.edu
|
