A swath of mangrove forest in Ten Thousand Islands captured by NASA during flyovers on December 1 2017 (three months after).
Image: NASA

Hurricane Irma may be a fading memory for those who didn’t experience its heavy rains or ferocious winds. But in the Everglades, the damage is still visible—and its ripple effects could last for years.

Aerial surveys led by NASA in December have revealed Hurricane Irma’s striking impact on remote swaths of Florida’s river of grass, which took a direct hit from the Category 4 storm last September. The surveys were follow-ons to a series of flyovers conducted last March and April, which scientists had planned before Irma as part of an assessment of mangrove forest evolution. In the wake of the storm, they are helping researchers understand how ecosystems recover from a massive disturbance.

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“It’s staggering how much was lost,” Lola Fatoyinbo, principle investigator for the project, said in a statement. “The question is, which areas will regrow and which areas won’t.”

The first airborne surveys after Hurricane Irma plowed through the region revealed enormous patches of dead seagrass south of the mainland, and entire mangrove forests stripped of their leaves further north along the coast. But there were also early signs that the ecosystem would bounce back, particularly in the often drought-stricken Florida Bay, which received a big pulse of freshwater during the storm.

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Image: NASA

The latest survey, which involved a NASA research plane scanning some 500 square miles of the Everglades with G-LiHT, an airborne imaging system that includes LiDAR and other instruments, is helping scientists see the bigger picture.

David Lagomasino, a remote sensing scientist at NASA’s Goddard Spaceflight Center and co-investigator on the project, told Earther that the southwestern toe of Everglades National Park and Ten Thousand Islands—a vast network of coastal mangrove islets and marshes near Everglades City —were hit hardest by the storm. While the southwestern park now appears on the road to recovery, “Ten Thousand Islands is definitely having a much harder time,” he said.

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According to Lagomasino, preliminary data shows the height of the canopy decreased by about a meter and a half as taller trees were toppled. The total volume of the mangrove the forest was reduced by about 20 percent.

Based on what happened after hurricanes Wilma and Katrina in 2005, Lagomasino says he’d expect the hardest hit areas of the Everglades to take two to four years to recover if all things were equal. In the intervening decade, however, a host of other problems have gotten worse. They include sea level rise, which is pushing saltwater into freshwater marshes and causing their peat-rich soils to collapse, and drought caused in part by the diversion of freshwater into South Florida’s booming metro areas.

Researchers used a portable LiDAR system to capture scientists making measurements in the Ten Thousand Islands mangrove forest in a January field campaign.
Image: NASA

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As they continue to analyze the airborne data in conjunction with January surveys conducted on the ground and a longer-term satellite record, the team hopes to learn if parts of the Everglades that were stressed before the storm are taking longer to bounce back. Despite its remote location, Ten Thousand Islands is being transformed by saltwater intrusion and the impacts of channeled canals dug decades ago, according to the U.S. Fish and Wildlife Service. It’s possible that some of the more imperiled coastal sections will be lost to the ocean entirely.

In the long term all of this matters for humans, because the Everglades is the buffer that protects South Floridians against storm surge and rising seas. The water that flows through it from the north recharges the aquifers the region’s burgeoning cities rely on for drinking water. If the Glades are being weakened and lost by natural disasters, development and climate change, that’s bad news for the nearly seven million people living nearby.

A similar NASA-led aerial survey is headed to Puerto Rico this week to assess lingering damage to rainforests and coastal wetlands nearly seven months after Hurricane Maria. Time is of the essence when it comes to studying these battered landscapes. It’s hard to believe, but we’re less than two months out from the 2018 hurricane season.

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