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Algae
bloom kills record number of manatees
Florida's
endangered manatees have long suffered from human activity, but this
year they face an especially deadly threat hidden in the waters where
they swim.
CNN,
12
March, 2013
An
algae bloom off southwest Florida, called Florida red tide, has
killed 174 manatees since January, the highest number to die from red
tide in a calendar year, state wildlife officials said Monday.
A
red tide is a higher than normal concentration of a microscopic algae
that appears in the Gulf of Mexico. At high enough concentrations,
the algae can turn the water red or brown, hence the name.
Red
tides happen almost every year in southwest Florida and sometimes
last just a few weeks, but this year the red tide has lingered and
settled in an area of warm water where the manatees have migrated.
Baby manatees nursed back
to health Manatees frolic near swimmers
"It's
kind of filled in an area where they've congregated and are feeding
on sea grass where the toxins settle on," said Kevin Baxter, a
spokesman for the Florida Fish and Wildlife Conservation Commission.
Swimming with manatees in
Florida 2012: 'Red tide' closes Australian beaches
Those
toxins can affect the central nervous systems of fish and other
vertebrates, causing the animals to die.
Wildlife
officials and their partners have this year rescued 12 manatees
suffering from the effects of red tide. They asked the public to
alert them to other ailing manatees who may be showing a lack of
coordination and stability in the water, muscle twitches or seizures,
and difficulty lifting their heads to breathe.
Unlike
other algae blooms, red tides are not caused by pollution, the
wildlife service said.
"Red
tides occurred in Florida long before human settlement, and severe
red tides were observed in the mid-1900s before the state's
coastlines were heavily developed," the commission said.
The
blooms usually develop 10 to 40 miles offshore, away from man-made
nutrient resources, it added.
Red
tides were documented in the southern Gulf as far back as the 1700s
and along Florida's Gulf coast in the 1840s, the commission said.
"Fish kills near Tampa Bay were even mentioned in the records of
Spanish explorers."
Manatees
are listed under the Endangered Species Act of 1973. Conservation
efforts have led to an increase in the manatee population, the
commission said, and the U.S. Fish and Wildlife Service is working on
a rule that would reclassify the manatee from endangered to
threatened.
Most
manatees die from collisions with watercraft or from "cold
stress" in chilly waters, Baxter said.
The
CNN article dismisses 'red tides' as a 'natural phenomenon', but the
National Geographic seems to disagree.
“Scientists
say some studies have linked red tide to global warming because algae
thrive in warmer water”.
Toxic
Algae May Contaminate More Seafood
Blooms
of one kind of "red tide" algae—which create ocean dead
zones—may be more frequent as the world warms, especially in North
America's Puget
Sound region (map),
according to Stephanie Moore of NOAA's West
Coast Center for Oceans and Human Health.
The
Alexandrium
catenella
algae species produces a poison that can accumulate in seafood and
subject humans to everything from vomiting to muscle paralysis to, in
rare cases, death.
Moore
and colleagues at the University of Washington created localized
computer models that depicted future ocean and weather patterns. The
group identified environmental conditions that are ideal for algae,
particularly water temperature. By forecasting how oceans might warm,
for example, the models predicted how climate change would change the
algae's growth patterns down the road.
"We
found that, not only will the risk for toxic blooms increase within
the present-day bloom season, which is typically between July and
October, but the bloom season itself will also expand," Moore
said.
"We
could see blooms beginning up to two months earlier in the year,
compared to what we've seen historically, and they may also last up
to one month later in the year."
As
temperatures rise, some warmer-water algae species may also expand
into traditionally cooler waters. Other spots currently suitable for
blooms could simply become too warm for the tiny plants.
Likewise
certain harmful algal species might no longer grow at all in the peak
of summer, she added. For these species, "instead of having just
one bloom season in later summer and early fall, we might start
seeing two smaller seasons—one in spring and one in late fall."
Such
shifts could temporarily close down shellfish fisheries due to safety
concerns, and overall create more problems overall for those who try
to keep the human food supply safe.
"If
they aren't testing for a certain toxin because it's never occurred
in a place [or time], there is a potential for contaminated seafood
to get to the public," Moore said.
"So
it's really going to call for increased vigilance," she added.
"We hope a benefit from studies like this might be to better
prepare managers for the different blooms that might occur."
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