Sanibel's mangroves are rebounding after Ian, but new threat looms

SANIBEL ISLAND, Fla. (WINK) — A new study shows that as sea levels rise and rivers shift sediment flow, the way mangroves store carbon could change from place to place and over time.

Mangroves pull carbon dioxide out of the air and turn it into energy, just like all plants do. They lock a lot of that carbon into their roots and soil for decades, even centuries.

These tangled, root-heavy forests aren't just mangroves—they're a natural carbon bank.

"The storage of carbon benefits everyone in terms of the global temperature changes that are happening," said Eric Mildbrandt with the Sanibel-Captiva Conservation Foundation.

Researchers, including Mildbrandt, say that the system is starting to face pressure from above and below.

"What this study is suggesting is that mangroves, as sea levels start to rise, there are going to be changes to the morphology of the coast," Mildbrandt said.

That change is already happening in Southwest Florida. Sanibel Island is a barrier island, and sea level rise is happening at fairly high rates in this area—seven millimeters per year.

In Fort Myers, sea level rise accelerated during the 1990s and has continued. Around Cape Coral or Punta Gorda, some of those cement docks along the sea walls are underwater at high tide now, and in the past, they weren't.

In a perfect world, mangroves would move inland, following the water up higher ground.

"However, what we have done in Florida is we've provided obstacles to their migration, things like sea walls, roadways, other development," Mildbrandt said. "That will decrease the amount of mangroves on our coastline."

Mildbrandt says that, over time that has big carbon implications.

"Over generations, you could see less storage in the marine environment, and that means as we continue to produce more and more carbon dioxide emissions, it'll just accelerate the process of warming and also of sea level rise," Mildbrandt said.

Mildbrandt says Southwest Florida's mangroves are still relatively healthy, even rebounding after Hurricane Ian. Globally, not every region is as lucky—in some parts of Southeast Asia, mangroves are cleared for shrimp farms and palm oil, removing that natural coastal protection and carbon storage altogether.

Neighbors plan to hold a community meeting ahead of the planning and zoning meeting on July 14th. If the project moves forward, it could eventually head to the Glades County commissioners for final consideration.

WINK News contacted Glades County officials and the developer for comment. 

Our team is waiting for a response.