By: Megan Williams
Coral Restoration Foundation is hard at work each day to restore the reefs in the Florida Keys. The decline of the once dominant reef-building species, Staghorn (Acropora cervicornis) and Elkhorn (Acropora palmata) corals, are due to a number of stressors, including disease, coral bleaching, and sea urchin die-off. While Coral Restoration Foundation uses it’s innovative Coral Tree Nursery™ and works to combat the threats that face Florida Keys and Caribbean reefs, projects worldwide have been developed to restore reefs in various areas, and are tailored to the unique challenges and threats that face each reef area. One such restoration project is occurring on Hawaiian reefs.
The coral reefs in Hawaii are experiencing a similar decline in reef quality as the Florida Keys reefs, but are a result of a different variety of threats and stressors. One of the Hawaiian reef’s biggest threats is invasive algae. Invasive algal species, such as Gracilaria salicornia (gorilla ogo), and Kappaphycus/Eucheuma spp. (smothering seaweed) were both introduced into the bay for aquaculture purposes during the 1970s. Since then, the fast growing algae has outcompeted native species and smothered and killed many of the native corals that are key to the entire reef ecosystem. With such a dramatic decline in the Hawaiian reef quality and life, an initiative was taken in 2005 by a small group of agencies led by The Nature Conservancy and the University of Hawaii to remove this alien algae and restore the native reefs.
To efficiently remove large quantities of this invasive algae, The Nature Conservancy of Hawai’i developed a floating platform barge with an underwater vacuum device, which is known as the ‘Super Sucker’. To operate a ‘Super Sucker’, two divers navigate the reef with a 100 foot hose and suction the algae underwater. The algae is then pumped to a sorting platform on the deck of the barge, where scientists are able to sort through and pull out any of the native species, which are then returned to the reef. The invasive algae is placed into bags, dried, and distributed to local taro farmers to be used as fertilizer. This efficient method can remove between 600 to 1,000 pounds of algae per hour. To date, this process has resulted in the removal of over 10 tons of invasive algae from Hawaii’s reefs.
On Maunalua Bay Reef, a restoration project was undertaken to remove leather mudweed, an alien alga species that attracts and traps sediment, resulting in a thick carpet that smothers native corals and depletes the oxygen in the reef. In 2009, the Maunalua Bay Reef Restoration Project was instigated, with the goal to remove the invasive algae, create employment, and establish expanded and sustainable local reef management efforts for the future. With the completion of the project, a total of 23 acres of reef ecosystem was cleared of 9 million pounds of invasive algae. With 100% of this invasive algae composted to local farmers, the effort was efficient and sustainable. This restoration effort cleared the sand bottom and hard limestone habitat, allowing native seagrass and coral recruitment to begin rebuilding the ecosystem throughout the bay.
Our coral reefs are rapidly changing. In different areas of the world, a variety of stressors have led to the deterioration, depletion, and degradation of reefs. However, with an understanding of the specific stresses, threats, and vulnerabilities that a reef faces, steps can be taken to restore them. With the aid of the ‘Super Suckers’ in Hawaii, reefs are being given the opportunity to shift back from algae to coral dominated substrates, which can ultimately lead to a more diverse and healthy ecosystem.
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