A native sea urchin that helps keep algae from smothering reefs is showing signs of disease, with patches of missing spines, in Maunalua and Kaneohe bays, and authorities are calling for the public’s help as they investigate the problem.
The species involved is the collector urchin, or hawae in Hawaiian, which has relatively short spines and has been used to control invasive algae. Sick urchins were first reported in February in Maunalua Bay and cropped up this month in Kaneohe Bay.
"We’ve seen a little bit of disease in a few places, and we’re trying to get a handle on it," said Frazer McGilvray, administrator of the Division of Aquatic Resources of the state Department of Land and Natural Resources. "At this point we don’t know what’s causing the disease or what the disease is."
On Friday the department issued a news release asking oceangoers to report any sightings of sick urchins, including date, time and location, but refrain from touching the creatures. Collector urchins get their name from their tendency to collect debris on their back.
"The public has eyes and ears across the entire state in much greater numbers than we do," McGilvray said. "We can start to get a much more comprehensive idea of where this disease may be occurring."
His department is working with the U.S. Geological Survey, The Nature Conservancy and the University of Hawaii to address the problem and monitor affected areas weekly. Results will be posted online at the team’s Reef Response website, dlnr.hawaii.gov/reefresponse.
"I’m absolutely delighted with the support we are getting from the feds and the NGO and the university," McGilvray said.
Biologists from The Nature Conservancy first reported the problem in February, when they saw sick urchins on an artificial reef in Maunalua Bay. Wildlife staff from the U.S. Geological Survey did an assessment and lab tests on the urchins that ruled out the possibility of parasites and suggested a disease was causing progressive loss of spines.
On May 6, DLNR and USGS staff responded to reports of urchins with similar lesions in Kaneohe Bay and found that about 10 percent of the urchins on one patch reef had the problem. On Wednesday a survey of several patch reefs in Kaneohe Bay found about 3 percent of collector urchins with signs of the disease.
"Disease is a natural occurrence in an ecosystem," McGilvray said. "Just look at the common cold. You get cycles of disease that come up and then disappear again. What we’re trying to find out is, is this a natural occurrence, is it seasonal? We just don’t know."
Collector urchins can play a vital role in maintaining the health of coral reefs, which are the backbone of the ecosystem. The state has transplanted collector urchins from its hatchery into Kaneohe Bay to manage invasive seaweed and has never seen any hint of disease in the hatchery, McGilvray said.
