Mud-loving alga covering Maunalua Bay.
Maunalua Bay: 2 million pounds of alien algae removed.
Suzanne Case, executive director, The Nature Conservancy of Hawai‘i.
Just half a century ago, Maunalua Bay was a gorgeous, productive marine playground. Laura Thompson remembers as a young girl riding her horse out into its clear waters.
“I lived right next to what was called Lucas Springs, Kalauha‘eha‘e. We kids had horses. We would ride our horses out toward the reef, all sand bottom, and jump off and hold their tails and come in.”
One of Carol Wilcox’s early memories is wading with her grandmother through the seagrass meadows of Kuli‘ou‘ou, to dig for clams.
Today, muddy sediment roils the waters, the seagrass pastures are threatened by an invasive mud-loving alga and the clams are long gone. Thompson said she has found masses of jellyfish infesting a spring-fed coastal Kānewai Pond that once ran with fingerling ‘ama‘ama—mullet.
Thompson and Wilcox are leaders in an effort by the community-based Mālama Maunalua and The Nature Conservancy of Hawai‘i to restore the degraded bay. Through the National Oceanic and Atmospheric Administration (NOAA), the Maunalua project was awarded $3.4 million in American Recovery and Restoration Act (ARRA) funding to clear sections of the bay of the invasive alga Avrainvillea amadelpha, or leather mudweed.
“It’s not very often that you get an opportunity like this, where you have the funding to attack a problem that can make such a big difference for both a community and the environment,” said Suzanne Case, the Conservancy’s Hawai‘i Executive Director. We’ve dubbed the project ‘The Great Huki’ and believe it will have tremendous impact.”
Maunalua Bay is a broad, south-facing indentation in the south O‘ahu coastline, nestled between two prominent volcanic features, Koko Head to the east and Lē‘ahi or Diamond Head to the west. Once a succession of valleys dominated by ranches, dairies and small coastal villages, the land along the bay is now a densely populated string of Honolulu suburbs.
Estuaries and historic fishponds that once trapped sediment have been filled for housing or dredged for boating. The population explosion on O‘ahu has increased fishing pressure. And alien marine species have dramatically changed the biology of the bay.
“There’s an enormous sense of urgency here. We’re at a tipping point,” Wilcox said. “We are at risk of losing the bay as a healthy resource.”
The proposed Avrainvillea removal project is an extension of a volunteer effort by the Conservancy and Mālama Maunalua, which in three years has removed more than 30 tons of algae from a half-acre plot at Paiko. While the area is small, the mudweed-pullers have seen success –– native species are coming back.
The mudweed was first reported in Hawai‘i in 1981. Kim Peyton, a marine botanist at the University of Hawai‘i who has worked in the area, believes it was able to colonize damaged areas of the seafloor after a series of severe storms and two hurricanes in the 1980s and early 1990s. Maunalua now has 54 acres of extremely dense mudweed infestation.
Avrainvillea is found from shallows that are exposed at low tide, all the way into water 70 meters deep. It grows slowly, but has expanded inexorably in recent decades. Left to its own devices, the weedy alga overwhelms native algae and marine pastures of the endemic seagrass, Halophila hawaiiana. What’s more, Peyton said, the Avrainvillea attracts and traps sediment, creating an oxygen-starved environment which prevents some native marine life from flourishing.
In areas where Maunalua volunteers have removed tons of mudweed, however, native marine life is returning. That’s why, when federal stimulus funds became available, the Conservancy and Mālama Maunalua formed a partnership to apply for the funding through NOAA.
There were three priorities to qualify for ARRA funding: The project needed to be shovel-ready, create jobs and have a strong restoration impact. “To the Conservancy’s and Mālama Maunalua's credit, they hit all three,” said Eric Co, of NOAA’s Restoration Center.
“We thought, ‘Wouldn't it be wonderful if we could tip the scales back in the bay’s favor?’” said Manuel Mejia, the Conservancy’s community-based marine program manager. “This project will allow us to hit a triple bottom line: environmental restoration, economic recovery through job creation, and community capacity building.”
The two-year, $3.4 million invasive algae removal project includes jobs, equipment and scientific studies. The program will hire at least 60 people from the community for 14 months, working full and part time removing the leather mudweed. Others will monitor the impact and conduct related scientific activities. The program anticipates clearing 22 acres of Avrainvillea infestation on the Kuli‘ou‘ou reef flats and smaller impacted areas in Maunalua Bay. The program expects to begin hiring before the end of the year.
“The best way to remove Avrainvillea is manually—we know that. So this is the ideal solution: hiring people from that community and hitting the area as hard as they can,” said Co.
But there is more to Maunalua’s plight than mudweed, and Mālama Maunalua is also continuing to work on its other problems.
“We identified three threats to Maunalua Bay,” Wilcox said. “Algae, sediment flowing in from the land, and unsustainable fishing. We have a conservation action plan that’s very focused on those threats. What we’re trying to do is effect conservation at a meaningful scale in an urban area. This hasn’t happened here before, but we believe that it absolutely can happen."