Noticias

Ola de calor extrema afecta corales de Florida / As seas get hotter, South Florida gets slammed by an ocean heat wave

POR EFE – Las primeras señales del estrés por calor de los corales que han visto sus buceadores son enfermedad y blanqueado severo en lugares de la barrera coralina del estado

Los arrecifes de coral también se están resintiendo de las elevadas temperaturas que este mes se vienen registrando en el sur de Florida (Estados Unidos) no solo en tierra sino también en el mar, advierten las organizaciones que se dedican a protegerlos.

La Coral Restauration Foundation (CRF) indicó que las primeras señales del estrés por calor de los corales que han visto sus buceadores son enfermedad y blanqueado serio en lugares de la barrera coralina de Florida como Cayo Sombrero y las llamadas Rocas secas orientales, ambos en las islas (cayos) situadas entre el territorio continental de Estados Unidos y Cuba.

Esta organización, que trabaja desde 2007 en respuesta a la casi desaparición de las especies de coral otrora dominantes en la barrera floridana debido a múltiples factores, no ha visto todavía señales de afectación en las granjas submarinas donde crían los corales con los que reemplazan a los muertos o enfermos.

No obstante, sus voluntarios han interrumpido la implantación de corales de granja en los arrecifes en restauración y además están llevando a instalaciones en tierra muestras de cada genotipo de dos especies de corales, Acropora cervicornis, coral cuerno de ciervo, y Acropora palmata, coral cuerno de arce.

Ojo vigilante

«Tenemos el ojo vigilante puesto en nuestras granjas y sitios de restauración y estamos preparados para ajustar nuestra respuesta cuando sea necesario», señaló CRF en un mensaje en redes.

La barrera coralina de Florida, que va desde el norte de Miami hasta Cayo Hueso, en el extremo sur del estado, es la tercera más extensa del mundo, y en origen estaba formada principalmente por las dos especies de coral ya mencionadas.

CRF afirma haber restaurado desde 2007 más de 17.500 pies cuadrados (0,16 hectáreas) de arrecifes mediante un método que consiste en cortar pedazos de coral sano del tamaño de un dedo y colocarlos en árboles de coral bajo el agua.

Cuando alcanzan el tamaño adecuado, en un período de seis a nueve meses, se implantan en las zonas de la barrera coralina que se encuentran en restauración.

Ecosistemas vulnerables de Florida

Los arrecifes de la zona de los Cayos de Florida estaban en nivel 1 de alerta de blanqueamiento antes de la ola de calor, según la Administración Nacional de la Atmósfera y los Océanos (NOAA).

Otras organizaciones dedicadas a proteger los corales también han alertado en los últimos días sobre los efectos nocivos que puede tener el calentamiento de las aguas del Atlántico en un ecosistema tan vulnerable como la barrera coralina de Florida.

Además del blanqueado, que debilita los corales, desde 2014 los arrecifes de Florida resultaron devastados por una enfermedad que hace que pierdan su tejido y se petrifiquen, que afecta a más de 20 especies.

Esa enfermedad, originada en Miami, se ha extendido por la mayor parte de los arrecifes de coral de Florida, así como los de países del Caribe.

Retiro de corales

En 2018, el Equipo de Rescate de Coral de Florida, dirigido por la Comisión de Conservación de Vida Silvestre y Pesca de este estado y un programa de la NOAA, comenzó a retirar corales de los arrecifes antes de que resultaran afectados por la enfermedad y los distribuyó en acuarios públicos de Estados Unidos, a fin de salvaguardar la diversidad genética y ayudar en una futura restauración.

Un año después las autoridades ambientales de Estados Unidos pusieron en marcha un programa urgente para detener la destrucción de siete arrecifes de coral icónicos de los Cayos de Florida debido a los huracanes, el calentamiento global, nuevas enfermedades y sobrecarga humana.

«Casi 90% de los corales vivos que alguna vez dominaron los arrecifes se han perdido», indicó la agencia federal, que calificó de catastrófica esta desaparición.

Los arrecifes coralinos no solo protegen las costas del efecto de erosión a causa de las tormentas, al reducir el impacto de las olas, sino que además son el hábitat natural de más de 4.000 especies de peces y numerosas plantas marinas.

As seas get hotter, South Florida gets slammed by an ocean heat wave

By Jenny Staletovich – A dramatic increase in ocean temperatures around South Florida in early July caught scientists off-guard. They’re now rushing to help struggling coral on the only inshore reef in the continental U.S.

An ocean heat wave in waters around Florida has scientists worried about cascading disasters, from fueling hurricanes and coral bleaching to exacerbating record heat on land.

Ocean temperatures have soared five degrees above normal since early July. This warming has been ignited by an El Nino weather pattern that’s collided with human-caused climate change.

“It’s bonkers. I don’t know how else to put it,” said Ben Kirtman, an atmospheric scientist with the University of Miami Rosenstiel School. “Normally when you break records, you break records by a tenth of a degree, maybe a quarter of a degree. … Here, we’re breaking it by five degrees.”

If scientists were to model the chances for such a spike in temperature, he said, it would amount to one in 250,000 years.

“It’s out of bounds from what we’ve seen,” Kirtman said.

Summertime seas around South Florida typically average about 88 degrees. But beginning in July, ocean monitors stationed along the coast began recording temperatures hovering in the low 90s. In Florida Bay, the wide shallow bay between the Florida Keys and the Gulf of Mexico, temperatures climbed above 98 degrees.

More ocean heat waves coming

South Florida’s ocean heat wave arrived as global ocean temperatures have steadily climbed since April. That prompted forecasters at the National Oceanic and Atmospheric Administration to predict that half the planet’s oceans could undergo heat waves by September.

In its last assessment of the warming planet, the United Nations Intergovernmental Panel on Climate Change found the Earth has heated up 2 degrees Fahrenheit in the past two centuries. Scientists warned that marine heat waves, like the one inflaming waters around Florida, would become more commonplace. That increasing heat, the IPCC said, could likely push some sea life “to the limits of their resilience.”

South Florida is already seeing some impacts. Warmer ocean waters reduce oxygen levels and that could impact fish populations. Three years ago a rare fish kill spread across waters off Miami as rising temperatures sucked oxygen from Biscayne Bay. Warming waters could also endanger spawning grounds for Atlantic bluefin tuna in the northern Gulf of Mexico, one of only two places where these tuna spawn. Hotter seas around Florida could also warm trade winds that help cool the state. That could exacerbate record heat already occurring on land.

This summer’s warming coincided with an emerging El Nino, a weather pattern that increases water temperatures in the Pacific and warms up the planet. But Kirtman said El Nino likely amplified temperatures already starting to creep upward.

“Certainly part of that warming is coming from El Nino, which is emerging. But usually there are cool spots associated with El Nino. We’re not seeing any cool spots,” he said.

That raises the question of what exactly is happening this year, Kirtman said.

“Is this just a ratcheting up of climate change, and then things are going to plateau for a little while and then there’ll be another ratchet up?” he said. “We don’t know.”

Scientists brace for coral bleaching

Corals are among the most precarious sea life struggling with climate change. Reefs around Florida and the Caribbean have struggled mightily over recent decades as increased pollution and disease have left them crippled. That has weakened their ability to function as a powerful barrier to hurricane storm surges.

In 2014, an outbreak of stony coral disease that started off Miami spread up and down Florida’s reef and into the Caribbean. Florida’s reef is the only barrier reef in the waters of the continental U.S. The disease knocked out foundation-building boulder coral on reefs that had already lost about 80% of their corals since the 1970s. The loss of those mounding coral that help bulk up reefs prompted scientists from across the country to form an emergency response to try to stop the spread and diagnose a cure.

The ocean heat wave now has scientists bracing for widespread coral bleaching.

“It’s not as if it’s just warming up here in Florida,” said Andrew Baker, a coral researcher at the University of Miami’s Rosenstiel School. He’s been looking for ways to make coral more resilient to hazards from climate change. “This is clearly kind of a Caribbean region-wide thing. And that’s why people are starting to think that it probably has some legs and is likely to be with us for a while.”

Warm summer waters typically trigger outbreaks of bleaching, when coral expel the algae they need to survive. But Baker said that warming typically occurs later in the season.

“That’s really why people are scared, because we have potentially another six or eight weeks of continued seasonal warming that’s going to add on top of this heat wave,” he said. “That’s really where the danger lies.”

A team of researchers from Andrew Baker's lab at the University of Miami has been studying the effect of warming and ocean acidification on coral in South Florida for several years.
A team of researchers from Andrew Baker’s lab at the University of Miami has been studying the effect of warming and ocean acidification on coral in South Florida for several years.

Baker is now working with the U.S. Department of Defense to develop more heat tolerant coral as part of a reef resilience project that could total more than $28 million. The project set a 2027 deadline to breed coral able to withstand a five-degree Fahrenheit rise in ocean temperatures.

“But now this summer we have temperatures that are already five or six degrees Fahrenheit warmer than the normal temperatures should be right now. So nature is outpacing even some of our most ambitious goals,” he said.

In the next few weeks, Baker said scientists will decide whether they want to move some coral into labs in advance of summer spawning, when corals release millions of eggs and sperm to produce babies. Heat stress can hamper that spawning. By moving them to labs, researchers can collect the babies and then release them back into the ocean. Researchers in his lab plan to inspect coral near Miami this week. In August they will look at a site in the Keys where more heat tolerant coral have already been planted.

“Even if we were to do that with just a couple of dozen corals, that would produce hundreds of thousands, if not millions of baby corals that might help restore the reef that wouldn’t otherwise be there,” Baker said.

During summer spawning, as seen here, corals release millions of eggs and sperm to produce babies. Scientists are concerned the ocean heat wave could hamper that spawning.
During summer spawning, as seen here, corals release millions of eggs and sperm to produce babies. Scientists are concerned the ocean heat wave could hamper that spawning.

Oceans store heat

Even if scientists succeed in breeding more resilient coral, Baker said that would only buy a little more time for the world’s reefs.

“Quite honestly, with the scale of the problem and the magnitude of the reef, these are all sort of drops in the bucket,” he said. “Here’s the thing that scientists have been saying is going to happen to reefs more and more often if we fail to do nothing. And what we really need to pay attention to is the root causes of climate change.”

more in original source https://wusfnews.wusf.usf.edu/environment/2023-07-19/as-seas-get-hotter-south-florida-gets-slammed-by-an-ocean-heat-wave