11th ICRS Abstract book - Nova Southeastern University

7-49
The Role Of Injury And Temperature in The Initiation And Prevalence Of The
Coral Disease, Skeletal Eroding Band
Cathie A PAGE* 1,2 , Bette L WILLIS 1,2
1 ARC Centre of Excellence for Coral Reef Studies, Townsville, Australia, 2 School of
Marine and Tropical Biology, James Cook University, Townsville, Australia
Skeletal eroding band (SEB) is the most prevalent coral disease on the Great Barrier Reef
(GBR) and affects a greater range of host species than any other coral disease globally to
date, yet little is known about its etiology or the environmental factors influencing its
prevalence. In this study, both field surveys and experimental studies indicate that warm
temperatures enhance the prevalence of SEB. Prevalence was greatest in summer in
seasonal disease surveys between 2002-2007 in the northern GBR, supporting a link
between warm temperatures and disease prevalence. Moreover, enhanced prevalence
when temperatures were greater than summer seasonal means suggests that elevated
summer water temperatures drive increases in SEB. This hypothesis is supported by
evidence from artificial injury experiments designed to test the role of injury and
temperature in the initiation of this disease. Colonisation of injuries by Halofolliculina
corallasia, the putative pathogen of SEB, was significantly greater on corals maintained
in aquaria at 30°C than on those maintained at both 24°C and 27°C. However, summer
water temperatures in the northern GBR were not always sufficiently high to enhance
ciliate colonisation rates in field experiments. Moreover, ciliates failed to form migrating
disease bands accompanied by tissue lysing on any of three coral species tested
experimentally, irrespective of water temperature, suggesting that although H. corallasia
is an early coloniser of recently exposed coral skeleton, it may not be the causative agent
of tissue loss. Alternatively, interactions with additional environmental or microbial
agents may be required before ciliates become pathogenic. When migrating bands of H.
corallasia were present, they were however associated with whole colony mortality as
well as reduced growth and reproductive output in acroporid colonies in the northern
GBR.
7-50
A Disease Outbreak On A Healthy Reef: A Mechanism For Recruitment And
Increased Diversity
Kathryn ROSELL* 1 , Laurie RAYMUNDO 2
1 Silliman University, Dumaguete, Philippines, 2 University of Guam, Mangilao, Guam
In the Philippines, coral disease outbreaks and impacts to reefs over time have been
poorly documented. Here, we present data from a year-long monitoring of an outbreak of
Black Band Disease (BBD) in the Marine Protected Area of Apo Island, Negros Oriental.
In June 2006, four large colonies of Echinopora lamellosa with an average mean
diameter of 8.4 ± 5.9 m were observed with multiple Black Band lesions. These colonies
were marked, and all other E. lamellosa colonies within a 50 m radius from this original
reef area were located, mapped and examined for lesions. Disease progression on
marked colonies was monitored for one year and other potential hosts were examined
periodically. Three of the four original Echinopora colonies showed 90-95% mortality at
12 mo, and no other colonies had developed signs of disease. At 12 mo, a large lesion
was observed on a nearby colony of Coeloseris mayeri, progression was rapid and the
colony died within a month later. Therefore, this particular infection showed rapid
progression and high mortality limited to very few colonies, in spite of the proximity of
other potential hosts. At present, BBD is still progressing on the remaining tissues of the
colonies. The exposed skeleton of the dead E. lamellosa colonies has begun to show signs
of recovery via regrowth of small remaining patches of healthy tissue and via coral
recruitment. Disease outbreaks are often catastrophic, resulting in widespread mortality
of reef-building corals. However, our observations describe an episode of Black Band
Disease in a marine reserve which greatly impacted very few colonies has opened up new
substrates for recruitment. We speculate that such an epidemiological pattern may reflect
the behavior of a disease on a relatively unimpacted reef and can act as a mechanism for
opening up new substrate for recruitment.
Oral Mini-Symposium 7: Diseases on Coral Reefs
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