"The north end of the bay is where we are focusing our efforts, because that's the leading edge of the invasion."
Dr. Eric Conklin
Hawai'i Director of Marine Science
Venture out on the water in O‘ahu’s Kāne‘ohe Bay and you are likely to see a pair of odd-looking boats called Super Suckers—giant, barge-mounted vacuum cleaners that suck invasive algae off the reef. For Kāne‘ohe Bay, the Super Suckers are a game changer: the difference between returning its coral reefs to health or watching them succumb to the chokehold of invasive algae.
In 2005, The Nature Conservancy partnered with the State and the University of Hawai‘i to develop the Super Sucker, which can remove well over 1,000 pounds of algae an hour. Today, both The Nature Conservancy and the State Division of Aquatic Resources have vessels operating in the bay. Together, crews are clearing the invasive seaweed off the reef and then seeding the reefs with native sea urchins that feed on the algae and keep it from growing back.
“Working in tandem with the State, we removed 250,000 pounds of invasive algae from more than 20 acres of reef last year,” says Suzanne Case, the Conservancy’s Hawaiʻi executive director. “And all of the algae have been given to local farmers for use as fertilizer and compost.” (Click here to view a video on the Kāne‘ohe Bay "Reef Revival" project.)
At its Anuenue Fisheries Research Center, the State has raised 200,000 native sea urchins and released them onto the bay’s reefs, where they eat the small pieces of algae left behind by the Super Suckers. “On reefs where we have placed the urchins, algae re-growth after a year is about five percent,” says Dr. Eric Conklin, the Conservancy’s Hawai‘i marine science director. “On reefs without urchins, algae can re-grow within six months.”
A Bay Out of Balance
Kāne‘ohe Bay is O'ahu's largest and most beautiful bay. Traditionally, it was home to some of the highest numbers and greatest diversity of fish and corals on O‘ahu. But over time these populations have plummeted, in large part due to the threats posed by invasive algae, overharvesting and land-based sources of pollution.
Invasive algae were introduced into the bay for aquaculture about 30 years ago. Fed by nutrient-rich sediment, and without healthy populations of native plant-eating fish and sea urchins to keep them in check, they quickly spread. Today, they form thick, tangled mats that are destroying the bay’s ecology and turning its reefs into an algae-smothered wasteland.
“The bad news is that these algae species are the very worst introduced marine species in the state,” says Dr. Eric Conklin, the Conservancy’s Hawai‘i director of marine science. “They smother and kill native corals, which are the core structural organisms of the entire ecosystem.”
The good news is that their distribution is still restricted. The algae were introduced and became established in the central portion of the bay. According to Conklin, there are effective natural barriers that prevent the algae from spreading south. But to the north there’s one continuous fringing reef that goes up the entire windward coast and, essentially, around the island—a very real corridor for dispersal.
“The north end of the bay is where we are focusing our efforts, because that’s the leading edge of invasion,” Conklin says. “The plan is to clear the north end and work our way back, keeping the algae contained inside the bay. With two Super Suckers we can get ahead of the invasion, removing algae faster than it can grow and spread – and that is going to make a big difference for the bay. ”
The goal is to clear the entire north end of the bay of the worst invasive algae by 2015.
We Need Your Support
Since its development in 2005, the Super Suckers have removed more than 1 million pounds of invasive algae from Kāne‘ohe Bay.
To operate the device, two divers equipped with a 100-foot hose descend below the surface and feed algae into the vacuum, which sucks it up to a sorting platform where it is placed into bags, dried and distributed to local farmers for fertilizer. Without damaging other marine life, each Super Sucker can remove more than 1,000 pounds of invasive algae an hour.
The tools and knowledge to stop the invasion and reclaim the bay exist. But to do it, The Nature Conservancy needs your help.
“Coral reefs take thousands of years to build, but only decades to destroy,” says Case. “The Nature Conservancy urges you to komo mai kau māpuna hoe: dip in your paddle and join the effort. With your support, we can reclaim Kāne‘ohe Bay and protect its marvelous marine life for generations to come. “