See how Hurricane Idalia shifted shorelines of Pinellas barrier islands

North of touristy Clearwater Beach and west of Dunedin sits a cluster of quiet islands.

They are state parks — lacking the accessibility and white sand beaches to the south. Instead, these barrier islands are home to redfish, loggerhead turtles and gulls.

Hurricane Idalia’s storm surge widened island passes, thrashed vegetation and displaced nesting wildlife. In exchange, coastal Pinellas — the most densely populated county in Florida with 3,425 people per square mile — was largely protected from the worst of Idalia’s surge.

Historically, these islands are constantly changing, said Al Hine, a marine geologist and professor at the University of South Florida St. Petersburg.

Honeymoon Island and Anclote Key are the more stable of the local barrier islands, according to Hine. This is the unlikely benefit of a seagrass die-off in the 1950s that destabilized sand deposits off the coast and washed sand ashore nearby islands.

“So, Anclote Key grew by 30% of its entire length within just a decade or so,” Hine said.

Just as natural phenomena can build beaches, they can also take them away. Boaters, scientists and environmental stewards noticed an eastward shift of these local barrier islands in the wake of Idalia.

“That’s how they actually maintain themselves,” Hine said. “That sand is eroded from the front side and pushed to the back side. So, the whole island migrates into the lagoon.”

Davina Passeri, an oceanographer with the U.S. Geological Survey, said barrier islands act as an important buffer zone during storms.

“Along these barrier islands, the dunes are really the first line of defense against water levels and storm surge,” she said.

Dunes block the impact of waves crashing into beaches, which protects coastline infrastructure and reduces inland flooding.

Natural processes eventually wash sand back onto eroded beaches, but Passeri said this can take up to a decade.

The real danger that lies in eroding shorelines is the chance of hurricanes reaching a barrier island already weakened by a previous storm.

“That makes your beach more vulnerable to storm impacts the following year,” she said.

These photos taken by the Tampa Bay Times show chinks in the armor left by Hurricane Idalia on Pinellas’ northern barrier islands.

Anclote Key

Barbara Hoffman, 66, is the president of Friends of Anclote Key, a volunteer organization that manages public access to the state park’s historic lighthouse.

The island is 3 miles off the mainland, with no road access. Hoffman’s first trip to Anclote Key after Idalia was aboard her husband’s seaplane, where Hoffman said she got a bird’s-eye view of the erosion.

“On the west side of the island — where the cabbage palm trees are — looks like a lot of that beach is gone,” Hoffman said.

The island saw about 3 feet of storm surge during Idalia, which was caught on a park ranger’s outdoor camera.

In addition to the knocked-back vegetation, a few lost generators and minor delays to the lighthouse restoration project, Hoffman said the storm wiped out sea turtle eggs during a critical nesting period.

“The sea turtle nesting for the season was a washout,” Hoffman said.

Anclote Key is the northernmost isle along Florida’s Gulf Coast for sea turtle nesting before reaching the Panhandle. Idalia brought surge waters that pummeled nests for about 12 hours. Hoffman said all 10 of the island’s endangered loggerhead sea turtle nests were destroyed.

Hoffman said she’s already seeing signs that Anclote Key is bouncing back. Bald eagles are returning to their nests. In two weeks, the sea oats, beaten down by surge, will prop back upright. Changes to the barrier islands are normal, she said.

“It’s part of their life. It’s not like anyone lives out there,” she said. “The islands just kind of moved a little bit, but they looked good. They looked really good.”

Three Rooker Island

Capt. Brian Mathay has worked as a fishing guide in Pinellas for 18 years. He said it doesn’t take much for the sands to shift. A hurricane or just a strong wind could dramatically change the channels he navigates from one day to the next.

Taking his boat out after the storm, Mathay said Idalia’s worst scarring showed on Three Rooker Island. A channel recently formed through the middle of Three Rooker was widened by the storm.

“Just over the last 10 years, it’s broken apart,” he said. “There’s now like an 8-foot pass in the middle.”

Mangroves and bird habitats were battered by storm surge and high winds, Mathay said.

“There’s almost no trees left on it at all,” he said. “Whereas before, there was a bunch of trees and the bulrush and the grass and all the seagulls and terns nested in. That’s just all gone.”

Honeymoon Island

Fishing trips out of Honeymoon Island, one of the most visited of these northern barrier islands, are Mathay’s bread and butter.

He noticed a new cut-through, about 1 mile south of the island’s northern tip. Idalia blew a hole through the island, and he said continued erosion would open that pass even more.

“It used to just be you can see through to the beach, but now there’s water rushing out there on the high tide,” he said. “With the tides and everything, it starts washing it out more and more.”

The 1921 Tarpon Springs Hurricane, the last major storm to hit the Tampa Bay area, cut Hog Island in two and created Honeymoon and Caladesi islands. The channel between them is now known as Hurricane Pass. Over the last century, shifting sands have replenished what used to be a 9-foot-deep channel.

A dredging project two years ago deepened the pass, but after Idalia, Mathay said that channel has almost completely filled back in.

Mathay agrees the barrier islands protected north Pinellas from the worst of Idalia’s surge but said they did little to stop the flooding.

Ozona Fish Camp, the Dunedin marina where Mathay keeps his charter boat, saw floodwaters rise to 2 feet.

“A lot of people got flooded,” he said. “We still had a significant storm surge.”

Mathay noticed one silver lining from the storm: The fishing is the best he’s seen all year.

Red tide in February and abnormally hot water temperatures this summer stifled the fish bite locally, he said. But a cooling wave after Idalia has brought the fish out of hiding.

“It’s all cycles, man. You know, fishing goes in cycles,” Mathay said. “You have good years and bad years and good times and bad times.”

And change is just a part of life on the water.

“The whole islands are shifting,” he said. “They’ve changed year over year.”

Times staff writer Max Chesnes contributed to this report.