Miami-Dade County

UM study: ‘Fattened up’ coral could be better at fighting climate change

In the last 40 years, 98 percent of the staghorn coral on the Florida reef tract have been wiped out. The coral are among the fastest growing and provide a key building block in reefs. University of Miami researchers have now found feeding the endangered coral supplements can help them withstand increasingly harsh ocean conditions.
In the last 40 years, 98 percent of the staghorn coral on the Florida reef tract have been wiped out. The coral are among the fastest growing and provide a key building block in reefs. University of Miami researchers have now found feeding the endangered coral supplements can help them withstand increasingly harsh ocean conditions. University of Miami Rosenstiel School of Marine and Atmospheric Science

Like a jock beefing up for a big game, some corals could do far better at withstanding the heavy blows of climate change when pumped with supplements, according to a new University of Miami study.

The study looked at endangered staghorn coral, a fast-growing branching coral that once provided the scaffolding for much of Florida’s reef system. For the first time, the research found that vanishing staghorn might have a shot at withstanding the withering effects of increasingly warmer and more acidic oceans if the corals could consume enough food in advance to build up reserves.

The findings offer a rare glimmer of hope for declining reefs, suggesting a recovery plan is possible, said lead author Erica Towle, a coral physiologist at UM’s Rosenstiel School of Marine and Atmospheric Science.

“This is really one of the few good news stories we’ve had recently about corals and climate change,” she said.

Reefs have long battled multiple stresses — from pollution to boat anchors — and scientists say climate change has only weakened the resiliency of many corals and the symbiotic algae that live inside them and fuel their growth.

If temperatures rise too much, corals will expel the algae. Scientists don’t know why but decades of such events, called coral bleaching, show the effects can be devastating. In the late 1990s, a global El Niño weather pattern warmed water and led to a massive die-off of staghorn. Staghorn coverage on Florida reefs is now estimated at just 2 percent of what it was in the 1970s, a dramatic decline for reefs that are not only vital habitat for sea life but also provide the first line of defense against storm surge and rising seas.

UM researchers wondered if coral, like people, could essentially live off “fat” during times of stress.

“If you and I were starving, our bodies would rely on our fat reserves. It’s the same idea with coral,” Towle said.

So the teams tested eight genetically diverse colonies of staghorn, subjecting them to temperatures of about 86 degrees — the threshold for bleaching events in the Keys — and carbon dioxide concentrations predicted for the oceans by 2065.

Twice a week for eight weeks, half the corals were fed an extra boost of dried zooplankton — the tiny organisms corals eat in the wild. The other half got none.

While the unfed coral stopped growing by a significant amount, the coral getting extra food maintained a growth rate even under the harsh conditions, according to the study published last month in the journal PLOS ONE.

The findings could have significant implications for how reefs are managed in the future, Towle said. For one thing, coral grown in nurseries could be fattened up before being moved to restore troubled reefs.

Scientists also could better target limited conservation efforts, Towle said. If they can figure out which parts of the ocean are attractive to zooplankton, they can better select areas to protect.

“Some reefs have higher densities, just like some places on earth have more insects than others,” she said. “That would be a really good place to focus conservation efforts.”

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