[Coral-List] cold water coral kill

[Eugene Shinn]

Coral listers, Here is the article from todays 
Miami Herald concerning the recent cold water 
episode. Reminds me of the 1969/70 winter chill 
that killed about 80 percent of the Montastrea at 
Hens and Chicken reef and the 1977 (snow in 
Miami) cold water event that killed Acropora at 
Dry Tortugas. It demonstrates why Acropora never 
proliferated in some of the Acropora "critical 
habitat" areas. Gene

Coral in Florida Keys suffers lethal hit from cold

BY CURTIS MORGAN

Miami Herald, Posted on Wed, Jan. 27, 2010

Bitter cold this month may have wiped out many of 
the shallow water corals in the Keys.

Scientists have only begun assessments, with dive 
teams looking for ``bleaching'' that is a 
telltale indicator of temperature stress in 
sensitive corals, but initial reports are bleak. 
The impact could extend from Key Largo through 
the Dry Tortugas west of Key West, a vast expanse 
that covers some of the prettiest and healthiest 
reefs in North America.

Given the depth and duration of frigid weather, 
Meaghan Johnson, marine science coordinator for 
The Nature Conservancy, expected to see losses. 
But she was stunned by what she saw when diving a 
patch reef 2 1Ž2 miles off Harry Harris Park in 
Key Largo.

Star and brain corals, large species that can 
take hundreds of years to grow, were as white and 
lifeless as bones, frozen to death. There were 
also dead sea turtles, eels and parrotfish 
littering the bottom.
``Corals didn't even have a chance to bleach. 
They just went straight to dead,'' said Johnson, 
who joined teams of divers last week surveying 
reefs in the Florida Keys National Marine 
Sanctuary. ``It's really ecosystem-wide 
mortality.''

The record chill that gripped South Florida for 
two weeks has taken a heavy toll on wildlife -- 
particularly marine life.

On Tuesday, the Florida Fish and Wildlife 
Conservation Commission reported that record 
numbers of endangered manatees had already 
succumbed to the cold this year -- 77, according 
to a preliminary review. The previous record, 56, 
was set last year. Massive fish kills also have 
been reported across the state. Carcasses of 
snook and tarpon are still floating up from a 
large fish kill across Florida Bay and the 
shallow waters of Everglades National Park.

Many of the Florida Keys' signature diving 
destinations such as Carysfort, Molasses and 
Sombrero reefs -- as well as deeper reefs off 
Miami-Dade and Broward -- are believed to have 
escaped heavy losses, thanks to warming effects 
of the Gulf Stream. But shallower reefs took a 
serious, perhaps unprecedented hit, said Billy 
Causey, Southeast regional director of national 
marine sanctuaries for the National Oceanic and 
Atmospheric Administration.

PAST PROBLEMS

Coral-bleaching has struck the Keys in the past, 
most recently twice in the 1990s, preceding a 
die-off that claimed 30 percent of the reef 
tract. But those events, along with others that 
have hit reefs around the world, have usually 
been triggered by water hotter than what corals 
typically tolerate.

Healthy corals depend on a symbiotic relationship 
between polyps, the living tissues that slowly 
build the hard outer skeletons that give species 
distinctive shapes, and algae called 
zooxanthellae that give them their vibrant 
colors. But when ocean temperatures veer from 
their comfort zone too much or too long, the 
coral begin to shed that algae, turning dull or a 
bleached bone-white.

The effect usually doesn't immediately kill coral 
but can weaken it, slowing growth and leaving 
fragile reefs -- home to millions of fish, crabs 
and other animals -- more vulnerable to diseases, 
pollution and damage from boaters and divers.

Cold-water bleaching is unusual, last occurring 
in 1977, the year it snowed in Miami. It killed 
hundreds of acres of staghorn and elkhorn corals 
across the Keys. Neither species has recovered, 
both becoming the first corals to be federally 
listed as threatened in 2006.

This big chill, said Causey, shapes up worse.

``They were exposed to temperatures much colder, 
that went on longer, than what they were exposed 
to three decades ago,'' he said.

Typical winter lows in-shore hover in the mid- to high-60s in the Keys.

At its coldest more than a week ago, a Key Largo 
reef monitor recorded 52. At Munson Reef, just 
about a half-mile off the Newfound Harbor Keys 
near Big Pine Key, it hit 56.

At Munson Reef, said Cory Walter, a biologist for 
Mote Marine Laboratory in Summerland Key, 
scientists saw losses similar to what was 
reported off Key Largo. Dead eels, dead hogfish, 
dead coral -- including big coral head five- to 
six-feet wide, bleached white with only fringes 
of decaying tissue.

``They were as big, as tall, as me. They were 
pretty much dead,'' said Walter, who coordinates 
Mote's Bleach Watch program, which monitors reefs.

The dividing line for damage seems to be Hawk 
Channel, which parallels the Keys on the Atlantic 
Ocean side.

East of the channel, at reefs such as Looe Key, 
one of the top tourist sites, there was only 
light paling on some coral, she said. In Hawk 
Channel itself, there were dead sponges and 
stressed corals but not many outright dead ones.

SURVEYING DAMAGE

West of the channel toward shore, damage was more 
serious. Walter estimated 75 percent coral loss 
at one patch reef, though with poor visibility, 
it was a limited survey. Some nurseries growing 
small staghorn and elkhorn corals for restoration 
programs also may have been hard hit.

Over the next few weeks, scientists and divers 
from the Florida Keys National Marine Sanctuary, 
National Park Service, Florida Fish & Wildlife 
Conservation Commission, Mote Marine Laboratory, 
the University of Miami, Nova Southeastern 
University and other organizations will try to 
get a more complete picture of damage with reef 
surveys as far north as Martin County and as far 
south as the Dry Tortugas.

While they may not be able to save cold-damaged 
corals, Causey said, chronicling what dies and, 
more important
``We're going to know so much more about this 
event than any other event in history,'' he said.

© 2010 Miami Herald Media Company. All Rights Reserved.


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No Rocks, No Water, No Ecosystem (EAS)
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E. A. Shinn, Courtesy Professor
University of South Florida
Marine Science Center (room 204)
140 Seventh Avenue South
St. Petersburg, FL 33701
<eshinn at marine.usf.edu>
Tel 727 
553-1158---------------------------------- 
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