Coral scientists predict destructive summer months
BY TIMOTHY O'HARA
Citizen Staff
This spring's
unusually mild water temperatures and slick-calm days may have been good
for divers, but it has Florida Keys National Marine Sanctuary
Superintendent Billy Causey bracing himself for a severe coral bleaching
event this summer.
A mild winter and
already balmy sea temperatures, coupled with coral bleaching activity
last year, does not bode well for the health of the Keys' coral reefs,
which provide habitat for fish, a buffer from hurricane-induced waves,
and millions of dollars a year in taxable income from diving, fishing
and other tourism-related activities.
Bleaching occurs when
corals are stressed and lose their symbiotic algae, called zooxanthellae.
Corals can survive bleaching, but it makes it more susceptible to other
problems. Coral diseases, careless divers tromping on reefs, pollution
and other sources of stress can stymie coral's ability to recover.
Bleaching episodes have become more severe and more frequent in the past
few decades, scientists say.
Causey believes the
Keys' reef tract dodged a bullet last year, as late-season hurricanes
cooled down and circulated water around stressed corals that began to
bleach last summer. Coral colonies in the U.S. Virgin Islands and Puerto
Rico did not do as well. Since early October, the National Oceanic and
Atmospheric Administration has issued severe bleaching alerts for Puerto
Rico and the Virgin Islands.
Bleaching is both
widespread and intense, with colonies representing 42 species completely
white in many reefs in Puerto Rico. Surveys show 85 to 95 percent of
coral colonies were bleached in some reef areas. Reefs in Grenada are
bleached, with 70 percent of coral colonies suffering some impact, NOAA
officials said.
The Keys are coming
off a mild winter and weeks of clear skies and dry days. Sea
temperatures have ranged between 78 to 82 degrees along various parts of
the reef.
"I am really
concerned," Causey said. "We are on the verge of a mass bleaching
event."
Causey fears an event
similar to ones in 1997 and 1998. Keys coral reefs saw the largest
coverage declines from 1996 to 1998, with damage done by back-to-back
bleaching events in those years and during Hurricane Georges in 1998.
Coral decline since has slowed dramatically, but there has not been much
recovery, Causey said. Similar two-year weather patterns began in 2005
and have carried forward in 2006.
Rising sea
temperatures and elevation, coral bleaching and coral disease have some
calling for the government to enact laws and plans to counteract global
warming. The National Wildlife Federation has called on both the federal
and state government to come up with a climate plan that addresses
lowering carbon dioxide and other greenhouse-gas emissions.
"Outside of the
Arctic, there is no place that is feeling impacts of global warming more
than the Keys," said Jerry Karnas, an outreach coordinator with the
National Wildlife Federation. "Florida is the fifth biggest producer of
carbon dioxide ... Corals are already being stressed and global warming
is acting like adding steroids."
Karnas and Causey, who
say the reef is an "indicator species" of the overall health of the
ocean, called the ecosystem a "canary in the coal mine."
"Changes are taking
place all over, and we are seeing elevated sea temperatures on a global
scale," Causey said. "What is happening is intense bleaching for longer
periods of time."
The Florida Keys reef
lost 37 percent of its stony coral cover since 1996, according to an
annual survey of the reef. A study by University of Georgia scientists
said 27 percent of reefs worldwide have been lost, with another 16
percent at serious risk of loss. Elkhorn and staghorn coral, the
dominant shallow-water reef builders, have been among the hardest hit
with losses recorded as high as 80 percent throughout the Caribbean. In
the Keys, more than 90 percent has been wiped out since the 1970s,
scientists say.
Some of the Keys' more
pristine reefs, Looe Key and Molasses Reef, did suffer some bleaching
last year, but recovered, said Cory Walter, who administers the Bleach
Watch for Mote Marine Laboratory on Summerland Key. Some reefs closer to
shore, Cheeca Rocks and Newfound Harbor near Little Palm Island,
suffered more extreme cases.
"It [water
temperature] is going up pretty quick and we want to get out ahead of
it," Walter said.
The sanctuary and Mote
Marine created Bleach Watch last summer to monitor events before, during
and after outbreaks. Volunteer divers conduct field observations to
monitor coral bleaching. Sanctuary and NOAA scientists will analyze
satellite and monitoring data and issue current bleaching condition
reports throughout the summer.
Walter will hold a
seminar on the Bleach Watch program at 6:30 p.m. June 6 at the Key Largo
Library and at 6:30 p.m. June 7 at the Marathon Library. She also plans
to hold a seminar in
Key West,
but a date has not been set. The seminars are open to the public. For
more information, contact Walter at
305-745-2729,
ext. 301, or check out Mote's coral bleaching Web page at:
http://isurus.mote.org/Keys/bleaching.phtml
tohara@keysnews.com |
