Cascading environmental impacts feared from ‘wasteland’ of Maui fires

In the wake of the devastating Hawaii wildfires, experts fear a broader environmental catastrophe is only just starting to unfold.

The fires have torn through vegetation and probably left toxic chemicals in their wake that could easily be flushed into creeks and the ocean. The extent of the damage won’t be known for some time, but experts worry about impacts on native plants and animals that aren’t adapted to thrive with fire. That flora and fauna will struggle to survive in charred landscapes and polluted waters.

“When a fire like this comes through, and everything is destroyed, it hurts your soul,” said Kimberly Thayer, a program associate at Mauna Kahalawai Watershed Partnership.

For now, the focus of conservation groups in Maui is on those who have been hurt by the fires. There have been at least 55 deaths reported, but the toll is expected to rise. The fires also burned homes and left the historic town of Lahaina in ruins.

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“We have staff, family, friends and colleagues that are facing unimaginable loss,” said Heather Starck, the executive director of the Coral Reef Alliance. “The people are the most important right now to everyone.”

Still, the time will come when those working on the ground will turn their attention to native plants and wildlife, which carry cultural significance to Indigenous Hawaiians, support the local economy and contribute to driving tourism to the islands.

Of primary concern are the corals off the state’s shores. The reefs next to any land that burned are at risk — roughly 2,000 acres burned in six fires, Hawaii Emergency Management officials said Thursday afternoon — but experts are particularly worried about the reefs near Lahaina, such as the Olowalu Reef, which is home to some of the oldest reef structures in the Hawaiian islands.

Runoff and debris from the land are the main threat, though ash raining into the ocean could also block sunlight necessary for photosynthesis from reaching the reefs.

Jennifer Smith, a coral reef expert at the University of California at San Diego, described the fires as having created a “massive wasteland” of chemicals and other toxic substances that could be washed into the oceans during a downpour. Fires also destroy vegetation, accelerating runoff, she said.

“Think about people’s garages and what they were storing in there,” she said. “That’s all been turned to ash.”

Smith said the sediments, ash and debris could effectively bury the reefs if they were to enter the oceans in large quantities. If the runoff were to carry fertilizers or sewage rich in nitrogen and phosphorus, Smith said the reefs could also run the risk of an algae bloom, which can overgrow and smother corals.

The fires come at a time when Hawaii’s coral reefs are already stressed. During 2014 and 2015, unprecedented portions of the reefs were bleached, with up to half of some reefs killed by the higher El Niño water temperatures. The reefs also face myriad threats such as increased coastal development, pollution and overfishing.

Manuel Mejia, the Hawaii program director for the Coral Reef Alliance, said experts were already bracing for a bleaching event later this year if the oceans continue to warm. The National Oceanic and Atmospheric Administration declared the arrival of an El Niño in June.

“Corals are resilient, but it may be too much, all at once,” he said. He said having such a severe fire next to a coral reef area in Hawaii is unprecedented.

The fires could also pose a threat to the native vegetation on land, though experts said that in some regards, the factors that have made the wildfires so devastating will also blunt their impacts to native flora and fauna.

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The fires were exacerbated by a dried-out landscape and the spread of flammable invasive grasses across abandoned farm fields. Smith said the absence of the same rains that proved so elusive in alleviating dry conditions could help prevent runoff from the oceans into the water. And Thayer said much of the burn scar already lost native species, leaving behind fewer to be further devastated by the fires.

Still, there will be consequences. The islands already suffer from nonnative plants and animals that have wreaked havoc on species that evolved to live on islands with little competition. Wildfires in Hawaii directly kill plants and animals, and they also accelerate the spread of nonnative grasses that bounce back more easily after a blaze, crowding out the regrowth of native species and creating more fuel for the next fire.

Thayer cited bees as a species that could be hurt. Native Hawaiian plants such as the bright yellow ilima flower attract these pollinators, and they are still “scattered around,” Thayer said. Fires can further diminish the presence of these flowers, in turn precluding the native bee species from pollinating these plants.

Thayer said the soil seed bank — the natural storage of seeds within the soil — is also threatened by high temperatures. Unlike in the western United States, where moderate blazes can help some species release seeds from their cones, fire in Hawaii doesn’t help seeds germinate or spread, let alone grow, Thayer said. She said with each passing fire, the likelihood of there being a viable seed bank remaining in the soil goes down.

She recalled a fire that tore through a native forest habitat in Maui at the end of last year. While the impacts of the fire are still not fully known, and damage assessments from researchers are ongoing, she said, there are signs of hope: Native ferns are growing new fronds, and some of the burned trees and shrubs are putting out shoots. But Thayer said it will take time to understand whether these fledgling plants can outcompete the nonnative species.

“When the fire went up the mountain, tears were shed,” she said. “Now this, with lives lost?” She trailed off, then spoke. “It’s really bad. It’s a crazy thing.”