Winter chill takes toll on Florida Keys coral

[sce56]

Source: LA Times

Winter chill takes toll on Florida Keys coral
Scientists begin early assessments of the damage on marine life, but initial reports are bleak.
Dead coral Reporting from Miami - January's bitter cold may have wiped out many of the shallow-water corals in the Florida Keys.

Scientists have only begun assessments, but initial reports are bleak. The damage could extend from Key Largo through the Dry Tortugas islands 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 the frigid weather, Meaghan Johnson, marine science coordinator for the Nature Conservancy, expected to see losses. But she was stunned by the devastation when she joined a dive team surveying reefs in the Florida Keys National Marine Sanctuary. The divers were looking for "bleaching," a telltale indicator of temperature stress in corals. Star and brain corals, large species that can take hundreds of years to grow, were as white and lifeless as bones, frozen to death, she said. Dead sea turtles, eels and parrotfish also littered the bottom. "Corals didn't even have a chance to bleach. They just went straight to dead," Johnson said. "It's really ecosystem-wide mortality." The record chill that gripped South Florida for two weeks took a heavy toll on wildlife -- particularly marine life.

The Florida Fish and Wildlife Conservation Commission reported that a record number of endangered manatees had succumbed to the cold this year -- 77, according to a preliminary review. The previous record, 56, was set last year. The warm Gulf Stream is believed to have protected deeper areas, but shallower reefs took a serious, perhaps unprecedented, hit, said Billy Causey of the National Oceanic and Atmospheric Administration. Coral-bleaching has struck the Keys in the past, most recently twice in the 1990s, preceding a die-off that claimed 30% 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 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 corals their vibrant colors. But when ocean temperatures are too hot or cold for too long, corals shed that algae, turning dull or a bleached bone-white.
<snip>
Cold-water bleaching last occurred in 1977, when it snowed in Miami, killing hundreds of acres of staghorn and elkhorn corals across the Keys. Neither species has recovered, and in 2006, both became the first corals to be listed as threatened under the federal Endangered Species Act. This year's big chill, Causey said, 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. During this cold spell, a Key Largo reef monitor recorded 52.

Read more: http://www.latimes.com/news/nation-and-world/la-na-cold-coral31-2010jan31,0,6453643.story

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A dead coral in the Upper Keys shows signs of temperature stress. (Nature Conservancy / January 29, 2010)

So what is the explanation for this cold snap the upset caused by global warming which will cause various deviations in temperature ranges in both directions?

[timeforpeace]

1. Warm bad for coral. Cold bad for coral. It's a wonder it even exists.

[mainer]

2. LOL! you echoed my thoughts.

poor coral. nothing suits it.

[jpak]

3. Actually, we have cold-water hard corals in the Gulf of Maine

that form extensive reefs in deep waters...

http://www.lophelia.org/

:hi:

[timeforpeace]

4. Then maybe the extremely short-term observations (a few days after the cold snap) are incorrect.

[jpak]

6. Different coral species have different temperature tolerances

Tropical and subtropical corals have a very narrow range of temperature tolerance.

Deep water corals are vulnerable to warming as ocean circulation and temperature depth profiles change in response to climate change.

But I think in FL reefs dead is dead...

:(

[timeforpeace]

8. Well of course. Plus the observations are faulty. And I snorkel in the Keys quite a bit

as well as all over the Caribbean and the coral around Florida is just fine. You can always find an isolated coral head like this.

[onehandle]

5. That's pretty much true of all life.

A degree one way or another and no life may have ever developed on Earth.

Unless God created the Earth, of course.

[sce56]

7. The coral reefs have been around for a great many years

But may not last many more as they are constantly being stressed by Man and weather.
From Wiki

The most significant threat to the Great Barrier Reef is climate change.<49><50> Mass coral bleaching events due to rising ocean temperatures occurred in the summers of 1998, 2002 and 2006,<51> and coral bleaching will likely become an annual occurrence.<52> Climate change has implications for other forms of life on the Great Barrier Reef as well - some fish's preferred temperature range lead them to seek new areas to live, thus causing chick mortality in seabirds that prey on the fish. Climate change will also affect the population and available habitat of sea turtles.<53>

Another key threat faced by the Great Barrier Reef is pollution and declining water quality. The rivers of north eastern Australia provide significant pollution of the Reef during tropical flood events with over 90% of this pollution being sourced from farms.<54> Farm run-off is polluted as a result of overgrazing and excessive fertiliser and pesticide use. Due to the range of human uses made of the water catchment area adjacent to the Great Barrier Reef, water quality has declined owing to the sediment and chemical runoff from farming, and to loss of coastal wetlands which are a natural filter.<55><56><57> It is thought that the mechanism behind poor water quality affecting the reefs is due to increased light and oxygen competition from algae.<58>

I have dived the reefs from Okinawa to Guam Hawaii and Mexico all of them have man foot prints all over them some more than others! To see them die will be a bad thing! Damm the people that have made this a reality in our life time!

[Yo_Mama]

9. But this has happened before

And the reefs are still there.

I don't think this freeze is nearly as bad as the 1895 freeze (after the 1894 snap), which flat out killed a lot of citrus groves.

I think we fail to realize that weather is quite variable. In a sense, this is "natural" weather for Florida - it's just not average weather.

Here's a timeline of Florida freezes:
http://www.flcitrusmutual.com/industry-issues/weather/freeze_timeline.aspx

There was a bad freeze in 1940. I assume that extremely sensitive corals in the shallowest water die and then grow back, because this has been happening for a long, long time.

[Yo_Mama]

10. But this has happened before, and the reefs are still there

Over the longer term, this weather is not that unusual.

Here's a history of the worst citrus freezes in Florida:
http://www.flcitrusmutual.com/industry-issues/weather/freeze_timeline.aspx

1894 and 1895 were very bad. I think Florida just gets hit with this weather rarely, but it's not abnormal when you look at the history.

Here's a bit of background: the Miami-South Florida NOAA historical page:
http://www.srh.noaa.gov/mfl/?n=floridahistorypage

I suppose the very temperature sensitive corals in the shallower water die off and then restock from deeper waters. (For the last 5 or 6 thousand years, the reefs we have now in S. FL are recent due to the water rise after the end of the last ice age.)

[ellenfl]

11. studies have been done showing that sunscreen is also killing

the coral. hopefully, the habitat can be saved, although things were looking dire BEFORE the cold snap.

ellen fl