Hawaii's coral reefs are in peril. What researchers are doing to restore coral ecosystems and preserve biodiversity

The Hawaiian islands are home to paradise, both above and beneath the ocean's surface.

However, nestled on the floor of the Pacific Ocean exists an underwater ecosystem so valuable to life on both land and sea, that its loss would spark a ripple effect of demise around the world.

Coral reefs are known as the rainforest of the sea and the foundation of the ocean, and they are dying almost everywhere they are found. Hawaii is one of the places on earth that would feel the loss of live coral the most.

The live coral provides flood protection benefits to more than 6,800 people living on the Hawaiian islands and $836 million in averted damages and economic activity, a report by the U.S. Geological Survey found.

With each 1-meter loss in reef height, the flood plain would increase across Hawaii by 33 square kilometers, putting about 9,200 more people in peril of flooding, and affecting more than $1.3 billion in property and economic activity, according to the report.

As climate change amplifies global warming, the corals are bearing the brunt of the damage.

Why are the coral reefs in Hawaii in decline?

All over the world, mass bleaching events are erasing the once vibrant hues of corals, as too-warm water causes algae to expel from the organisms' tissues, leaving them a grayish white color. Ocean acidification, caused primarily by an uptick in carbon dioxide absorption from the atmosphere, is reducing the calcification rates of corals, leaving the framework for the rock formations unstable.

The corals reefs of Hawaii are currently classified as "fair" but in decline, with significant bleaching events taking place in the region in 2014 and 2015, Danny DeMartini, co-founder and director of science for Kuleana, a Hawaii-based coral restoration nonprofit, told ABC News.

Damage to the Hawaiian corals is "widespread," especially in areas, such as bays, where there is limited water flow and temperatures heat up quickly, DeMartini said.

Reefs are essential to both marine and land dwelling species, as about 25% of all marine life depend on coral reefs. The stress of recent bleaching events caused some of our fish populations and certain reefs to drop by up to 50% in the last 10 years, DeMartini said.

The aspiration to protect the land and sea are embedded in Hawaiian culture, and native Hawaiians consider themselves as custodians of the environment, said actress and singer Auli'i Cravalho, who has partnered with cat food brand Sheba, which uses fish products in its products, to raise awareness surrounding the immediate need to protect and preserve coral reefs worldwide.

Cravalho, whose lineage traces back to kings and queens that once ruled the Hawaiian islands, grew up in Kohala, a small town on the Big Island, where she saw first-hand the impact climate change has had on the coral reefs surrounding her home.

"I'm used to it being plentiful with fish and very colorful," she told ABC News. "And over the years, I've noticed that it has significantly degraded."

When the bleaching first occurs, there is a window of time in which the corals can rebound if they do not remain in that state of stress for too long, Heather Starck, executive director of the Coral Reef Alliance, an environmental nonprofit dedicated to coral reef conservation, told ABC News.

But the likelihood of reducing ocean temperatures in the near future is unlikely, forecasts show.

Marine researchers were already expecting a warmer-than-usual ocean surface temperatures due to an upcoming El Nino event this year, Starck said.

Unprecedented ocean temperatures are plaguing oceans

The planet is undergoing an unprecedented warming event. For the better part of a month, regions all over the world have experiencing record-breaking, dangerous heat on land.

Oceans are not faring much better.

About 40% of all the oceans around the world are currently experiencing a heat wave, according to the National Oceanic and Atmospheric Administration.

June marked the highest average global ocean surface temperatures ever recorded, and temperatures are not expected to cool in the coming weeks, the NOAA announced on Thursday.

Nearly the entire Pacific Ocean is measuring at higher-than-normal temperatures, including the equatorial Pacific, the Northeast Pacific, the Northwest Pacific in the Kuroshio extension region and the Sea of Japan and the Southwest Pacific just southeast of New Zealand, according to NOAA.

Other factors affecting corals and ocean health in Hawaii

Hawaii is also experiencing other stressors, such as wastewater pollution, sedimentation from runoff from streams and overfishing, Starck said.

Rubbish also often washes ashore due Hawaii's position in the North Pacific Gyre, as ocean circulation brings garbage to the coastlines, DeMartini said.

There are currently more than 88,000 cesspools throughout Hawaii, which discharges 53 million gallons of untreated sewage into the ground each day, according to the state.

Tourists who visit the Hawaiian islands are also decimating the destinations they seek in paradise.

The most popular coral reefs on the Hawaiian islands are likely being degraded by the very visitors they attract, a study published in Nature Sustainability in January found. The degradation typically happens in the form of diver contact and elevated pollution levels in areas that tourists frequent, researchers from Princeton University found.

"Hawaii is a really popular place to go snorkeling and diving, and so when those other stressors are happening on top of sea surface warming, then it can it can leave the corals really vulnerable to actually dying off," Starck said.

What is being done to conserve Hawaiian ocean waters

Efforts to conserve the biodiversity in Hawaii are being made on several fronts.

Studies have shown coral that undergo bleaching events in areas that have better water quality -- better managed fisheries and better managed tourism -- have a better chance of bouncing back, Starck said.

In 2016, the state of Hawaii banned the construction of new cesspools. The next year, the state passed a law requiring that all cesspools be converted and closed by the year 2050.

Kuleana, a Hawaiian word that translates loosely to "responsibility," has embarked in the utilization of pilot restoration techniques that can be affordable and scalable that we can take to all different communities on the islands to help recover, DeMartini said. One of them involves planting small structures onto the reef to accelerate the growth rate of the corals, and therefore restoring opportunity for the ecosystem to thrive and marine life to live and feed there, DeMartini said.

Like her alter ego Moana, Disney's Polynesian princess with a special affinity for the ocean, Cravalho has dedicated her voice to protecting her home from environmental destruction. A passion for microbiology since her school days has transformed to her using her celebrity to amplify the environmental advocacy needed to preserve the Hawaiian islands and other natural habitats around the world.

Gently informing people to avoid touching the coral, clean up after themselves at the beach and prevent extra waste by drinking from reusable water bottles can sometimes make the biggest difference, Cravalho said.

In the future, marine planners will need to prepare meticulously when a bleaching event is forecast to prevent further loss of live coral, Starck said.

Actions such as reducing anchoring, allowing fewer people near the reefs and targeted water quality improvements could be the difference in whether the coral are able to survive acute stressor events, she added.

"If we can just get that more into the planning, I think they will do much better in the long term," Starck said. "So, there is a hope in the story."

The Walt Disney Company is the parent company of ABC News.