Australian subtropical white syndrome: a transmissible, temperature-dependent coral disease

Abstract

Since 2000, a disease displaying white-syndrome characteristics has been observed affecting corals from the genus Turbinaria in the Solitary Islands Marine Park, New South Wales, Australia. Recently termed Australian subtropical white syndrome, this disease is transmissible through direct contact and by a predatory vector, but transmission through the water column has not been observed. In aquarium experiments, progressive tissue loss, extending from the region where healthy Turbinaria mesenterina fragments were in direct contact with samples of diseased coral, was noted in 66% of treatments. No tissue loss occurred in any of the controls or when healthy fragments were not in direct contact with diseased corals. Field experiments confirmed that the disease was infectious through direct contact. Further experiments showed that the rate of tissue loss was significantly higher when corals were exposed to summer temperatures (26 • C). These results suggest that temperature increases predicted in most climate change models could lead to the loss of dominant coral species, displacing other organisms that rely on corals for food and shelter. Finally, the present study showed that removal of the disease margin provides a management tool to minimise coral tissue loss during an epizootic.

Coral Diversity and the Severity of Disease Outbreaks: A Cross-Regional Comparison ofAcroporaWhite Syndrome in a Species-Rich Region (American Samoa) with a Species-Poor Region (Northwestern Hawaiian Islands)

“…For example, in the Florida Keys, Hudson [64] treated black band disease (70% effective) by removing the pathogen by suction and covering the affected area with modeling clay (lesion occlusion). In Australia, Dalton et al [65] found that mechanical removal of the advancing disease margin for Turbinaria colonies affected by a tissue loss disease ("white syndrome") was successful at halting the disease in 80% of the colonies. AWS might be effectively managed by either lesion occlusion or mechanical removal of affected parts depending on the severity of the disease on the colony and the colony morphology.…”

Assessment of disease lesion removal as a method to control chronic Montipora white syndrome

“…These results differ from previous studies in which lesion removal was successful at stopping disease progression. Lesion removal halted white syndrome on Turbinaria mesenterina (Dalton et al 2010) and growth anomalies on Acropora acuminata (Dalton et al 2010, Williams 2013. The etiologies and ecologies of diseases differ, which affects the efficiency of any treatment method.…”

“…Similar treatment methods employing lesion removal have proven successful for mitigating the damage inflicted by certain coral diseases (Hudson 2000, Dalton et al 2010, Williams 2013, Aeby et al 2015. Removing pathogen-afflicted areas of tissue by suction and covering the affected area with modeling clay was 70% effective in controlling black band disease on affected Oscillatoria membrancea in the Florida Keys (Hudson 2000).…”

“…Corals, like all other organisms, are susceptible to disease, and the declining health of reefs has led to disease outbreaks, incidences of which have increased worldwide (Goldberg & Wilkinson 2004, Bourne 2005, Miller & Williams 2007. Environmental stressors, including elevated seawater temperatures, nutrient input from runoff, and sedimentation, exacerbate the declining health of corals (Harvell et al 2007, Dalton et al 2010, Haapkylä et al 2011. The tissue-loss disease Montipora white syndrome has impacted the population of M. capitata in Ka -ne'ohe Bay, Hawai'i (USA), over the last decade (Aeby et al 2010).…”

“…The similar temporal pattern of infection among corals suggests that there may be an undiscovered environmental component affecting cMWS processes in M. capitata, which could have caused these spikes. Without the temporal resolution afforded by weekly sampling, this short-term increase in infection would have been missed.In previous work, decreases in morbidity and mortality were recorded following treatment of different types of disease lesions from various coral species (Hudson 2000, Dalton et al 2010, Williams 2013, Aeby et al 2015. Each of these studies reported benefits to coral survival as a result of treatment and should be considered as potential management actions in response to disease outbreaks.…”