Vol. 10, Issue 359 - Sunday, December 25, 2005 HAWAII'S CORAL REEFS Oh, no! A zit! GRETA AEBY, UNIVERSITY OF HAWAII INSTITUTE FOR MARINE BIOLOGY A growth anomaly (tumor) on rice coral. Coral disease is found on many reefs in Hawaii, but the quantity of disease is relatively small. Early research shows 17 types of coral disease on Hawaii reefs, but the long-term impact isn't yet known >> How to look for coral disease >> Special: Hawaii's coral reefs, cradle of life >>> Special: Amazing creature melds plant, animal and mineral By Diana Leone mailto:dleone@starbulletin.com?subject=http://starbulletin.com/2005/12/25/ SCIENTISTS have found diseased coral in the ocean off Maui, Oahu, the Big Island and Kauai, and even in the remote and pristine Northwestern Hawaiian Islands. And in some places, disease seems to be spreading. Coral disease shows itself in the form of abnormal growths (tumors) or discoloration, some nicknamed "zits" by researchers; by the loss of algae that live in the coral (bleaching); and by death of the coral animal itself, leaving behind only its calcium skeleton.
"Coral is a very simple animal. There's no cough or runny nose. We can't ask it, 'How are you feeling, dear? You look a little pale,'" said Greta Aeby, a University of Hawaii Institute of Marine Biology coral disease specialist. Looking for coral disease is just a few years old in Hawaii. But it's important, because damage from coral disease can be severe. In the Florida Keys, for example, nearly 90 percent of the most significant reef-building coral type (the genus Acropora) has died of disease. Aeby saw the destruction firsthand in Florida while working on her post-doctoral research. Since then, other scientists' research in Australia has shown increases in coral disease there, she said. Now she's among Hawaii scientists developing baseline information about how much disease is "normal" here and what causes the diseases they are seeing. Hawaii's main reef-building coral genus (Porites) is different from the one affected in Florida and early checks show disease at a much lower level, but Aeby said, "We can learn from the Florida Keys' past experience." Aeby said she hopes that "we as a people can take better care of our reefs, especially in the main Hawaiian Islands, to ensure that disease does not become a problem as has happened in other regions." Scientists in Hawaii began specifically looking for coral disease in the Northwestern Hawaiian Islands in 2002, around Oahu in 2004 and around Maui this year. Other observations of coral disease by scientists doing other projects on the Big Island and Kauai have been incorporated. GRETA AEBY, UNIVERSITY OF HAWAII INSTITUTE FOR MARINE BIOLOGY Thierry Work, a wildlife disease specialist with the U.S. Geological Survey, takes photographs of diseased coral at Mala Wharf, Maui, during a yearlong study funded by the Hawaii Coral Reef Initiative Research Program. While the Northwestern Islands are considered pristine, coral around the main islands has to cope with plenty of impacts from humans, including: soil, pollutant and nutrient runoff from land; overfishing; physical damage by snorkelers, divers and boaters; and overgrowth of algae, which can be spurred by a combination of the other factors.
With extensive research being done in the Northwestern Islands by various biologists, "we hope to have more collaboration and better understanding of whole ecosystems up there," Aeby said. Another benefit of that research could be improved knowledge for managing reefs in the main islands. Aeby hopes eventually to train scientists who are in the ocean for other purposes, and reef monitoring volunteers, how to recognize and record the signs of coral disease. Others' observations could be an early warning, bringing a closer look by disease experts, she said. Aeby and fellow researchers have found 17 types of coral disease so far in Hawaii and have begun to see some trends, she said at a recent talk about the research for other scientists and marine wildlife managers. Related work is looking at disease in native goatfish and butterfly fish, and in alien blue-line snapper (taape). Aeby's study of the Acropora (table coral) genus at French Frigate Shoals shows how coral disease can spread:» In 2002, she didn't find any coral disease.» In 2003, one of French Frigate Shoals' Acropora study sites was about 4 percent diseased with Acropora white syndrome, which causes massive tissue loss.» In 2004, three study sites were affected, with disease coverage ranging from 1.4 percent to 5.7 percent of the Acropora colony.» This year, of the three formerly infected sites, two again had Acropora white syndrome. "Next year we will be able to say for sure, but it appears to be spreading through French Frigate Shoals and spreading within each reef," Aeby said. Thierry Work: Applies crimescene investigative techniques to learn what is causing disease in wildlife, including coral
Greta Aeby: Has seen Caribbean reefs wiped out by coral disease and wants to protect Hawaii's reefs from the same fate Some disease in any plant or animal population is part of the natural order of things. By establishing a "normal" disease baseline for Hawaii corals, researchers will be able to raise the alarm if there is a spike in its occurrence. Though coral disease has been found at widespread sites in Hawaii, Aeby said, its prevalence on any one reef studied so far has remained at 5 percent or less, far less than the rates that wiped out Caribbean corals. It's too early to tell what factors may contribute to Hawaii's coral disease. Some might be sedimentation, fish density, water quality and the level of human use. "We're trying to document what we have right now. We're asking, 'Has this thing been there before?'" said U.S. Geological Survey wildlife disease specialist Thierry Work, one of Aeby's collaborators. Compared to disease studies for other animals, coral researchers have only recently begun standardizing how they describe diseases. So, "at this stage," Work said, "we're in the Middle Ages." BACK TO TOP
GRETA AEBY, UNIVERSITY OF HAWAII INSTITUTE FOR MARINE BIOLOGY Researchers are not sure if growth anomalies on coral harm it or not. HOW TO LOOK FOR CORAL DISEASE On a work trip in June to Maui, co-researchers Greta Aeby (University of Hawaii Institute for Marine Biology), Thierry Work (U.S. Geological Survey wildlife disease specialist), Steve Coles (Bishop Museum) and lab technician Dave Albert (collecting samples for UHIMB co-researcher Teresa Lewis) demonstrated the techniques used to look for coral disease. Underwater dives lasted about two hours per site. Work and Aeby each carefully noted the species and amounts of coral found 1 meter on either side of a 25-meter-long stretch of tape measure, laid as straight as possible on the ocean bottom. They also noted, and photographed, any coral disease within 3 meters of the tape measure. Coles took underwater photographs using a frame that allows a computer program to later calculate the amount and type of coral over a wider area. Albert collected samples of diseased and healthy corals, and the water immediately around them. Lewis analyzes the samples in the lab to determine what kinds of bacteria, viruses or other organisms are present in the vicinity of healthy and diseased corals. On Maui, the team surveyed coral for disease at Olowalu, Honolua, Kahekili, Kanahena, Molokini, Puamana, Mala Wharf, Maalaea and Sugar Beach. On Oahu in 2004, the team surveyed coral for disease at Kaneohe Bay, Hanauma Bay, Pupukea and Kahe. The sites were selected because they had good coral cover, Aeby said. In some cases they were sites for earlier coral research on other subjects. Article URL: http://starbulletin.com/2005/12/25/news/story03.html 1996-2005 The Honolulu Star-Bulletin http://www.starbulletin.com/