[Coral-List] cold water coral kill
hreyes at uabcs.mx
Mon Feb 1 13:58:15 EST 2010
estimados coralisteros, corals are slowly recovering in the southern gulf
of california, but mortality was intense in the mid gulf (25-26N), where
only small colonies remain and are being eaten by a large number of
acanthaster (its populations has more than doubled since the early 1990s)..
an analysis in course in our lab about sst at western mexico, shows that
temperature is rising about 0.02°C/yr in average, but also that annual
variation (standard deviation) is increasing faster than that. we now
think that the problem is not the warming itself, but the low probability
that corals eventually adapt to cold AND warm extremes in years to come.
UABCS, La Paz
> I can only wonder how much the corals of the entire region might
> ultimately show an increased tolerance to bleaching & especially disease
> in the coming years because of these colder temperatures. We know
> extremely cold temperatures in the GBR back in 2004 [Heron Island] saw a
> rapid bounce back following the low SSTs....what about recovery in the
> Gulf of California from cold water bleaching a couple years ago???
> Hoegh-Guldburg, O., M. Fine, W. Skirving, R. Johnstone, S. Dove and A..
> Strong (2005). Coral bleaching following wintry weather. Limnology and
> Oceanography 50(1): 265-271.
> On 1/27/2010 3:55 PM, Eugene Shinn wrote:
>> 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 1Z(2 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
>> 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.
> ****<>< *******<>< *******<>< *******<>< *******
> Alan E. Strong, Ph.D.
> NOAA Coral Reef Watch, Senior Consultant
> ...with AJH Environmental Services...
> National Oceanic and Atmospheric Administration
> NOAA Coral Reef Watch Program
> e-mail: Alan.E.Strong at noaa.gov
> URL: coralreefwatch.noaa.gov
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Héctor Reyes Bonilla
Universidad Autónoma de Baja California Sur
Departamento de Biología Marina
Apartado postal 19-B, CP 23080. La Paz, B.C.S.
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