Cooperatove Conservation Project

Hawaii Coral Reef and Native Algae Restoration

Removing Alien Invaders That are Smothering Hawai’i’s Reefs

Location: Far West Region: Hawaii

Project Summary: Volunteers, local communities, NGOs, businesses, and government agencies work together to remove invasive alien algae and to begin to restore Hawaii's coral reefs.
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Hundreds of volunteers remove Gracilaria salicornia from the reefs of Waikiki, O’ahu. (PHOTO BY BRUCE CASLER)
Resource Challenge

Hawaii’s coral reefs are home to an abundance of marine invertebrates and fishes, nearly 28 percent found solely in Hawaii. The spread of invasive, non-native marine algae is one of the greatest threats to Hawai‘i’s coral reefs and other near shore marine ecosystems. As alien algae spreads, it grows over and smothers coral reefs and native algal communities, killing extensive areas of native habitat.

This project is taking significant strides toward restoring and protecting Hawaii’s coral reef ecosystems by removing alien algae and restoring native species in Kane‘ohe Bay and Waikiki, O‘ahu, and by fostering community stewardship through education and volunteerism.

The initiative, which was sparked by a small group of agencies led by The Nature Conservancy and the University of Hawaii, has evolved into one of the largest grassroots partnerships in the state, and includes federal, state, and county agencies, local businesses, and thousands of volunteers from across the island.

Examples of Key Partners

National Oceanic and Atmospheric Administration (NOAA) Community-based Restoration Program, The Nature Conservancy of Hawaii, Hawaii State Division of Aquatic Resources, University of Hawaii, Waikiki Aquarium, the Hawaii Coral Reef Research Initiative, Coordinating Group on Alien Pest Species, the U.S. Department of the Interior, Reef Check, local businesses and community groups.

Results and Accomplishments

Removing alien algae from high priority coral reefs is key to the long-term survival of Hawaii’s reefs and the abundance of life that thrives there. Volunteers have removed more than 91 tons of the alien alga G. salicornia at more than a dozen community-based events over the past three years.

The Nature Conservancy recently developed and is testing a floating platform barge with a mechanized removal device, greatly increasing removal efficiency. The University of Hawaii, Waikiki Aquarium, Hawaii Coral Reef Research Initiative, and the Hawai‘i Institute of Marine Biology are also exploring a new invasive algae control technique that uses a native Hawaiian sea urchin (Tripnuestes gratilla) to graze any remaining invasive algae, and thereby help to prevent re-establishment after mechanical removal.

The State Division of Aquatic Resources, the Coordinating Group on Alien Pest Species, and The Nature Conservancy are now reaching out to communities statewide, offering education and volunteer opportunities for control, early detection, and rapid response to curtail the spread of invasive algae in other areas, and more importantly, to stop new infestations before they become established.


The Project is developing new mechanical and biological techniques for removing invasive algae, and using historic cultural practices for reestablishing native algae species at restoration sites.

Project Contact
Eric Co
Marine Conservation Program Coordinator
The Nature Conservancy of Hawaii



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