At nearly 25 miles long, the coral reef that lines Molokai's south shore is the longest fringed reef in the United States and all of its protectorates. It is a system that promotes astonishing biodiversity.
Divers know this, as do fisherman and scientists.
However, like many, if not most, coral reef systems throughout the planet, human activities have imperiled Molokai reef.
For nearly eight years, researchers have been keeping a close eye on Molokai to gain an understanding of what's happening.
"This particular reef system has a tremendous impact due to rife sediment," said University of Hawaii's Hawaii Institute of Marine Biology researcher Paul Jokiel, who has studied coral reefs since 1969.
The sediment — dirt and mud — washes into the ocean from Molokai's highlands, usually after it rains.
"Sediment runoff from islands is recognized as one of the main causes of coral reef degradation globally," said United States Geological Survey geologist Mike Field, who has been studying sedimentation on the Molokai reef since 1999. "It's a very big issue. Molokai has become very well-known in the scientific community."
Jokiel studies Molokai reef as part of the Hawaii Coral Reef Assessment and Monitoring Program (CRAMP). He and a small team of researchers, many of them UH students, are taking a look at the impact of sediment on coral.
The group has been looking at the way dirt from the highlands on Molokai's East End that has washed into the sea affects coral's health and its ability to spread. They also look at how coral responds to the stress of regularly getting coated with sediment, which suspends and resettles daily with the blowing of the trade winds.
But sediment isn't the only problem, Jokiel says.
Freshwater, he said, and nutrients from fertilizer runoff — nitrogen, phosphorus, and potassium — also stress coral out.
Nutrients promote the growth of algae, which then takes over; blocking out sunlight, an element without which coral cannot survive.
Jokiel and others trace the sediment problem back to overgrazing cattle in the 1800s.
Since then, he says, grazing animals — deer, pigs, goats — have ripped out vegetation that would otherwise secure topsoil and help soak up rain.
Field said that, according to data collected on soil loss on the mountain, the most noticeable spot where this is happening is Kawela.
"That's where some of the biggest changes to the land can be seen," Field said, though mud washes off the hills on Molokai's West Wnd as well.
Field's work focuses on the physics of reef sediment — how wind, waves, and other elements impact its travel patterns, or as Field put it, the "fate" of sediment on Molokai reef. He is in the process of publishing an atlas of South Molokai, something which has never been done before.
Kathy Chaston of the Hawaii Department of Land and Natural Resources Division of Aquatic Resources said that she has talked to many people who aren't aware of the connection between erosion and the health of the reef.
Chaston works under the US Coral Reef Task Force, an umbrella group established by presidential executive order in 1998. She focuses on land-based pollution in her study of the reef.
"We're focusing mauka-makai," Chaston said.
She said that sediment doesn't make for a pretty picture out on the reef at the moment.
"You might have some coral out there, but if it's not growing, it's not healthy."
Chaston, Jokiel and Field all say that while what is happening on Molokai reef has worldwide implications, they have the people of Molokai in mind first and foremost.
"It's driven by the local community," Chaston said.
Jokiel said that the fruits of all of this work will come in the form of public policies put in place that will protect Molokai reef.
While reversing the damage to the reef is a long road, Field said that the best action is to "stop the injury; stop the insult."
"These reefs do recover," Jokiel said. "You don't have to go out there and do heroic things like suck up the mud."
Still, the mud that currently suspends and resuspends daily on the reef would take years to clear.
"It won't take just a few years," Field said. "If that reef cleans up, it will take a very long time."
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