The importance of long-term monitoring of the Great Barrier Reef was highlighted this week, when scientists at the Australian Institute of Marine Science (AIMS) confirmed the prevalence of coral disease on the Reef.
Scientists within the AIMS long-term monitoring program have placed the disease they are seeing in a broad White Syndrome category. They hope to soon learn exactly what White Syndrome is.
"It’s more common on table corals. It starts at the base and works its way up. The disease breaks the coral tissue down, eventually killing it, " said Cathie Page a benthic ecologist on the AIMS long-term monitoring team.
Cathie Page has been a key member of the monitoring team for about three years. After clocking up about 150 dives each year spanning 48 reefs, she says she’s seen White Syndrome kill at varying rates.
"It could kill a colony of 2 metres in diameter in two weeks but in some other cases, it takes months to kill a large colony, " she said.
It’s true the disease could well have been present on the reef long before the AIMS long-term monitoring team became aware of it, but the scientists believe it is unlikely White Syndrome escaped them, especially during extensive surveys over the past decade.
"I don’t think it’s ever been as abundant as now because we would have picked it up during our surveys. If it’s rare we’re more likely to overlook it. But when it became more common in the years up to 1999, White Syndrome surveys were instigated."
In combination with White Syndrome, coral bleaching is a compounding concern. With rising water temperatures over the tropical summers, coral bleaching events are more widespread and happening more often, leaving little time for coral to recover. Scientists fear the disease could be spreading more quickly in corals weakened by bleaching.
"Bleached coral is not healthy and potentially more susceptible to diseases. We don’t know what’s causing this disease. It’s microscopic; it could be a range of things," Ms Page said.
Scientists have recorded the disease in northern waters during the winter months, making this a tricky disease to fathom. They’re also yet to pinpoint the agent killing the coral. "The pathology of the disease is yet to be examined. Samples have been sent off for testing," said Cathie Page.
An extensive examination of the diseased coral has to be carried out in a bid to draw up a profile of the potential threat. While there are a number of other potential diseases on the Great Barrier Reef common to other reefs around the world, this one appears to be different.
"It doesn’t fit the description of diseases found anywhere else in the world, so it might be specific to the Pacific."
AIMS scientists are collaborating with marine researchers overseas. A lot of work has been carried out in the Caribbean, but nothing seems to match the description of White Syndrome.
The first record of coral diseases came from reefs off Belize and Florida in 1973. It wasn’t until 1993 that diseases were noticed on the Great Barrier Reef. When the disease worsened in the late 90s the long-term monitoring team swung into action and started documenting its growth in earnest.
In 1999 only seven reefs were infected with White Syndrome; in 2002 33 reefs were affected out of the 48 studied by the AIMS long-term monitoring team. The highest number of infected colonies within one reef was 101 in a 1500-m2 area. That was on Carter Reef, an outer shelf reef in the Cooktown/Lizard Island sector. The syndrome killed those colonies infected and caused a decline in hard coral cover on this reef.
The disease challenges the idea of reef diseases being linked to pollution, like other coral diseases around the world. On the GBR, White Syndrome outbreaks are happening in pristine areas, outer reefs unharmed by coastal development and tourism.
"It has spread over inner, middle and outer reefs but seems to be more common on outer Barrier reefs in clear water with no sediment or nutrient problems. Outer-shelf reefs near Lizard Island off Cooktown in the northern GBR and the Capricorn Bunker reefs in the southern GBR are the worst affected areas.
On a broad scale, the researchers say the disease covers only a small proportion of the reef.
The AIMS long-term monitoring team has enlisted the help of marine researchers from other north Queensland institutions to help broaden the knowledge of this little known phenomenon. Researchers from James Cook University are collaborating on the project. For now AIMS researchers will continue detailed monitoring of the status of White Syndrome and try to find the key to unlocking the disease’s makeup.
For more information contact Theresa Millard, AIMS Science Communication, Phone: 07 47534250, 47534444, Mobile: 0409596271 Email: t.millard@aims.gov.au
Cathie Page, AIMS Reef Monitoring Team, Phone: 07 47534229 or Email: c.page@aims.gov.au
source: http://www.aims.gov.au/pages/about/communications/backgrounders/20020907-coral-disease.html 18oct02
TOWNSVILLE, Queensland, Australia - Scientists at the Australian Institute of Marine Science (AIMS) have confirmed the existence of coral disease on the world's longest reef, the Great Barrier Reef which stretches along Australia's east coast.
Researchers at the government institute do not have to travel far to see the giant reef - they just glance out their front door - but they have searched the world for a clue to the cause of the disease they have observed.
AIMS scientists working in the long term monitoring program say the disease they have documented is in a broad category known as White Syndrome. Soon they hope to learn exactly what White Syndrome is.
Cathie Page, a deep ocean ecologist on the AIMS long term monitoring team, says, "It's more common on table corals. It starts at the base and works its way up. The disease breaks the coral tissue down, eventually killing it." "It doesn't fit the description of diseases found anywhere else in the world, so it might be specific to the Pacific," she says.
In the three years Page has been on the monitoring team, she has logged about 450 dives spanning 48 reefs.
She has seen White Syndrome kill at varying rates. "It could kill a colony of two metres (6.5 feet) in diameter in two weeks but in some other cases, it takes months to kill a large colony," she said.
The first record of coral diseases came from reefs off Belize and Florida in 1973. In 1993 coral diseases were noticed on the Great Barrier Reef. When the diseases worsened in the late 1990s, the long term monitoring team started documenting their activity.
In 1999 only seven reefs were infected with White Syndrome; in 2002 33 reefs were affected out of the 48 studied by the AIMS long term monitoring team.
The highest number of infected colonies within one reef was 101 in a 1,500 square meter area. That was on Carter Reef, an outer shelf reef in the Cooktown/Lizard Island sector. The syndrome killed those colonies infected and caused a decline in hard coral cover on this reef.
AIMS scientists together with researchers from James Cook University who are collaborating on the project have recorded the disease in northern waters during the winter months.
Outer-shelf reefs near Lizard Island off Cooktown in the northern Great Barrier Reef and the Capricorn Bunker reefs in the southern Great Barrier Reef are the worst affected areas.
White Syndrome outbreaks are happening in pristine areas of the Great Barrier Reef, the AIMS teams says, on outer reefs untouched by coastal development and tourism. This means the reef diseases are not linked to pollution, as are other coral diseases around the world. Coral bleaching is also affecting the great reef, and scientists fear White Syndrome could be spreading more quickly in corals weakened by bleaching.
Coral bleaching is the name given to an event where coral expel their symbiotic algae due to extreme stress, such as unusually hot water, according to AIMS bleaching expert Dr. Terry Done. The bleached corals die if the stress is extreme or prolonged.
With rising water temperatures over the tropical summers, coral bleaching events are more widespread and happening more often, leaving little time for coral to recover.
"Bleached coral is not healthy and potentially more susceptible to diseases," said Page. "We don't know what's causing this disease. It's microscopic; it could be a range of things."
AIMS has sent samples of corals affected by White Syndrome away for testing. When the results come back, they will search for solutions that might save the corals of the Great Barrier Reef.
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