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Mitigating land-based stressors to protect coral reefs

Ka Mo‘olelo Moana

Planting native plants and natural barriers helps trap and settle sedimentation runoff upland and reduces its impacts on coral reefs. Coral Reef Alliance photo

In September 2015, ocean water temperatures reached sustained levels that catalyzed unprecedented coral bleaching worldwide. Hawaii’s corals were devastated with some areas experiencing up to a 50 percent mortality rate. This year, not only has Maui experienced lengths of record-breaking temperatures, it is experiencing a bleaching event that is predicted to be greater than the bleaching events of 2015.

Hawaii has a family of organizations working to protect coral reefs. Maui Ocean Center is dedicated to educating its guests about coral bleaching and reef etiquette while inspiring easy to make, habitual changes. For corals, environmental stressors are numerous: rising water levels, ocean acidification, water pollution, increasing ocean temperatures and more. While many look to the sea for solutions, it is equally important to address land-based issues, and organizations like the Coral Reef Alliance (CORAL) are doing just that.

The West Maui Mountains are revered for their beauty and sculpted valleys, but their significance transcends beyond ecological value. The mountains hold cultural, spiritual and religious importance for Hawaiians, which include historical and sacred sites. However, little is known of the conservation work taking place in the midslope region, an area once used for agricultural operations. With the closure of commercial agriculture, these lands have turned to degraded roads and barren grounds, becoming a source of sedimentation — the transfer of eroded soil particles into bodies of water.

CORAL, along with its partners and volunteers, is working to mitigate sedimentation pollution in the midslope region of the Wahikuli and Honokowai watersheds. The compacted, barren roads inadvertently funnel sediment-filled runoff and nutrient pollution into stream gulches that eventually connect to the ocean. Sedimentation smothers coral reefs while nutrients create algal blooms that cause disease. Together, these impacts reduce the resilience of corals, making them more susceptible to other stressors, like increasing water temperature associated with climate change.

Using holistic approaches over the past year, CORAL began implementing restoration initiatives called Best Management Practices (BMPs). CORAL is planting native plants, trees, grasses and using natural barriers, like coconut coirs, to slow water flow and allow suspended particles to settle further upland. In a forested watershed, plant root systems serve as soil anchors to prevent erosion. As new plants and trees grow, CORAL hopes to reinstate natural ecosystems that create more rainfall and help with flood control and ground water infiltration.

In the world of science, it is also important to monitor these efforts and share the results with landowners, farmers and developers to encourage adopting these practices. CORAL’s employees take measurements of plant species and growth, along with calculating the amount of sediment trapped in the BMPs. This will help ensure the validity of the practices taking place and provide greater feedback to share.

You can be a part of the solution to save Maui’s coral reefs. Join our restoration events on the second Saturday of every month from 8:30 a.m. to 12:30 p.m. For more information and to sign up, visit www.coral.org/maui. You can also join Maui Ocean Center for its quarterly Malama: Land & Sea road-to-reef cleanups (www.mauioceancenter.com).

The Coral Reef Alliance is a nonprofit, environmental organization that is on a mission to save the world’s coral reefs. We work collaboratively with communities to reduce direct threats to reefs in ways that provide lasting benefits to people and wildlife. In parallel, CORAL is actively expanding the scientific understanding of how corals adapt to climate change and applying this information to give reefs the best chance to thrive for generations to come. This combined expertise uniquely positions us to achieve our mission by rallying the conservation community around scalable and effective solutions for coral reefs.

* Larissa Treese contributed to this report. She is with the Coral Reef Alliance. Evan Pascual is the marketing and public relations coordinator at Maui Ocean Center. “Ka Mo’olelo Moana,” or “The Ocean Story,” is a monthly column submitted by Maui Ocean Center staff members. The center is open from 9 a.m. to 5 p.m. daily in Maalaea. For more information, call 270-7000.

** This article has a correction from the original published October 5, 2019.