Case Studies
Hawaii Coral Reef Native Algae Restoration:
Removing Alien Invaders Smothering Hawaii's Reefs
Non-native algae cover the beach in front of the Waikiki Aquarium after a swell. Local efforts have begun to remove the threatening algae from the area. (Photo credit: Jennifer Smith)
Hawaii’s reefs are home to an abundance of marine invertebrates and fishes, many of which are only found in Hawaii. One of the greatest threats to the coral reefs and other marine ecosystems is the spread of invasive, non-native marine algae, specifically Gracilaria salicornia, also known as gorilla ogo. This species of algae was once a source of agar, which was used as a solidifying agent in everything from ice cream to eye cream.
However, because it has no natural predators in Hawaii, it has begun to dominate the ocean floor, growing into thick mats covering swatches of the reef. As alien alga spreads, it grows over and smothers coral reefs and native algal communities, killing extensive areas of native habitat. Removing this alga from high priority coral reefs is key to the long-term survival of Hawaii’s reefs and the abundance of life that thrives there.
"Algal blooms are becoming increasingly common worldwide and can decimate coral reef ecosystems by overgrowing corals and decreasing biodiversity. No efforts currently exist to control invasive algae in the tropics on such a large scale as our efforts in Hawaii,” said Anne Rosa, Marine Conservation Project Coordinator for The Nature Conservancy of Hawaii. “To reach a greater scale, we have employed multiple strategies including the community-based initiatives of the Hawaii Coral Reef restoration project, as well as the development of new algae removal technology."
Hundreds of volunteers helped to remove the invasive algae, G. salicornia, from beaches in Oahu. Because this alga has no natural predator in Hawaii, it has come to dominate coral reefs there. (Photo credit: Bruce Casler)
Volunteers, local communities, businesses, government agencies and other organizations are working together to remove G. salicornia from the beaches and waters and to begin to restore Hawaii’s coral reefs. Native species restoration has begun in Kaneohe Bay and Waikiki, Oahu, and has evolved into one of the largest grassroots partnerships in the state. New mechanical and biological techniques for removing invasive algae has removed more than 88 tons of G. salicornia at more than a dozen events over the past three years.
Partner organizations in this project include: The National Oceanic and Atmospheric Administration, The Nature Conservancy of Hawaii, State Division of Aquatic Resources, University of Hawaii, Waikiki Aquarium, Hawaii Institute of Marine Biology, the Hawaii Coral Reef Research Initiative, Coordinating Group on Alien Pest Species, the U.S. Fish and Wildlife Service, National Park Service, Reef Check, private dive operators, local businesses, local community groups, and schools.
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