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Selective Impact of Disease on Coral Communities: Outbreak of White Syndrome Causes Significant Total Mortality of Acropora Plate Corals.

Hobbs JP, Frisch AJ, Newman SJ, Wakefield CB - PLoS ONE (2015)

Bottom Line: Following the outbreak, live Acropora plate coral cover at 5 m depth decreased significantly from 7.0 to 0.8%, while the cover of other coral taxa remained unchanged.Observations five years after the initial outbreak revealed that total Acropora plate cover remained low and confirmed that corals that lost all their tissue due to WS did not recover.These results demonstrate that WS represents a significant and selective form of coral mortality and highlights the serious threat WS poses to coral reefs in the Indo-Pacific.

View Article: PubMed Central - PubMed

Affiliation: Department of Environment and Agriculture, Curtin University, Perth, Australia.

ABSTRACT
Coral diseases represent a significant and increasing threat to coral reefs. Among the most destructive diseases is White Syndrome (WS), which is increasing in distribution and prevalence throughout the Indo-Pacific. The aim of this study was to determine taxonomic and spatial patterns in mortality rates of corals following the 2008 outbreak of WS at Christmas Island in the eastern Indian Ocean. WS mainly affected Acropora plate corals and caused total mortality of 36% of colonies across all surveyed sites and depths. Total mortality varied between sites but was generally much greater in the shallows (0-96% of colonies at 5 m depth) compared to deeper waters (0-30% of colonies at 20 m depth). Site-specific mortality rates were a reflection of the proportion of corals affected by WS at each site during the initial outbreak and were predicted by the initial cover of live Acropora plate cover. The WS outbreak had a selective impact on the coral community. Following the outbreak, live Acropora plate coral cover at 5 m depth decreased significantly from 7.0 to 0.8%, while the cover of other coral taxa remained unchanged. Observations five years after the initial outbreak revealed that total Acropora plate cover remained low and confirmed that corals that lost all their tissue due to WS did not recover. These results demonstrate that WS represents a significant and selective form of coral mortality and highlights the serious threat WS poses to coral reefs in the Indo-Pacific.

No MeSH data available.


Appearance of Acropora plate corals approximately 8 months after the White Syndrome (WS) outbreak and representation of the change in coral community composition caused by the significant and selective WS mortality.The photograph was taken during the follow-up surveys in October 2008.
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pone.0132528.g001: Appearance of Acropora plate corals approximately 8 months after the White Syndrome (WS) outbreak and representation of the change in coral community composition caused by the significant and selective WS mortality.The photograph was taken during the follow-up surveys in October 2008.

Mentions: To provide a more direct measure of mortality rates in Acropora plate corals specifically and to allow for comparisons between depths (5 and 20 m) across all eight sites, an additional survey was conducted at both depths at the eight monitoring sites [19]. In this second survey, the number of dead Acropora plate colonies was recorded within three replicate 30 m by 10 m transects (at each depth and site). The mortality rate was then calculated as the number of dead Acropora plate coral colonies divided by the total number of live and dead Acropora plate coral colonies. We used 42 tagged Acropora plate corals that had been affected by WS and subsequently died as references for the visual appearance of corals that had died due to the WS outbreak (Fig 1). Corals that recently died due to WS had intact fine-scale morphological structures and were colonised by green and brown turfing algae and could be easily distinguished from corals that had died in previous years (which had lost fine-scale morphological features and were colonised by other organisms such as coralline algae and coral recruits). Furthermore, during the initial WS outbreak (February to April), previously dead colonies accounted for less than 0.3% of all plate corals at the survey sites, and thus the number of dead plate corals in the follow-up survey (October) was strongly indicative of recent WS induced mortality. Between the initial outbreak and the follow-up survey (approximately 6 months later) no other obvious environmental impacts were observed (e.g. coral bleaching, storms, floods, Acanthaster outbreaks). Thus we have no reason to believe that anything other than WS caused the observed mortality in Acropora plate corals. Furthermore, we observed WS progress and kill 40 tagged plate corals during late April and May, providing further support that dead plate corals observed in October had died due to WS.


Selective Impact of Disease on Coral Communities: Outbreak of White Syndrome Causes Significant Total Mortality of Acropora Plate Corals.

Hobbs JP, Frisch AJ, Newman SJ, Wakefield CB - PLoS ONE (2015)

Appearance of Acropora plate corals approximately 8 months after the White Syndrome (WS) outbreak and representation of the change in coral community composition caused by the significant and selective WS mortality.The photograph was taken during the follow-up surveys in October 2008.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493122&req=5

pone.0132528.g001: Appearance of Acropora plate corals approximately 8 months after the White Syndrome (WS) outbreak and representation of the change in coral community composition caused by the significant and selective WS mortality.The photograph was taken during the follow-up surveys in October 2008.
Mentions: To provide a more direct measure of mortality rates in Acropora plate corals specifically and to allow for comparisons between depths (5 and 20 m) across all eight sites, an additional survey was conducted at both depths at the eight monitoring sites [19]. In this second survey, the number of dead Acropora plate colonies was recorded within three replicate 30 m by 10 m transects (at each depth and site). The mortality rate was then calculated as the number of dead Acropora plate coral colonies divided by the total number of live and dead Acropora plate coral colonies. We used 42 tagged Acropora plate corals that had been affected by WS and subsequently died as references for the visual appearance of corals that had died due to the WS outbreak (Fig 1). Corals that recently died due to WS had intact fine-scale morphological structures and were colonised by green and brown turfing algae and could be easily distinguished from corals that had died in previous years (which had lost fine-scale morphological features and were colonised by other organisms such as coralline algae and coral recruits). Furthermore, during the initial WS outbreak (February to April), previously dead colonies accounted for less than 0.3% of all plate corals at the survey sites, and thus the number of dead plate corals in the follow-up survey (October) was strongly indicative of recent WS induced mortality. Between the initial outbreak and the follow-up survey (approximately 6 months later) no other obvious environmental impacts were observed (e.g. coral bleaching, storms, floods, Acanthaster outbreaks). Thus we have no reason to believe that anything other than WS caused the observed mortality in Acropora plate corals. Furthermore, we observed WS progress and kill 40 tagged plate corals during late April and May, providing further support that dead plate corals observed in October had died due to WS.

Bottom Line: Following the outbreak, live Acropora plate coral cover at 5 m depth decreased significantly from 7.0 to 0.8%, while the cover of other coral taxa remained unchanged.Observations five years after the initial outbreak revealed that total Acropora plate cover remained low and confirmed that corals that lost all their tissue due to WS did not recover.These results demonstrate that WS represents a significant and selective form of coral mortality and highlights the serious threat WS poses to coral reefs in the Indo-Pacific.

View Article: PubMed Central - PubMed

Affiliation: Department of Environment and Agriculture, Curtin University, Perth, Australia.

ABSTRACT
Coral diseases represent a significant and increasing threat to coral reefs. Among the most destructive diseases is White Syndrome (WS), which is increasing in distribution and prevalence throughout the Indo-Pacific. The aim of this study was to determine taxonomic and spatial patterns in mortality rates of corals following the 2008 outbreak of WS at Christmas Island in the eastern Indian Ocean. WS mainly affected Acropora plate corals and caused total mortality of 36% of colonies across all surveyed sites and depths. Total mortality varied between sites but was generally much greater in the shallows (0-96% of colonies at 5 m depth) compared to deeper waters (0-30% of colonies at 20 m depth). Site-specific mortality rates were a reflection of the proportion of corals affected by WS at each site during the initial outbreak and were predicted by the initial cover of live Acropora plate cover. The WS outbreak had a selective impact on the coral community. Following the outbreak, live Acropora plate coral cover at 5 m depth decreased significantly from 7.0 to 0.8%, while the cover of other coral taxa remained unchanged. Observations five years after the initial outbreak revealed that total Acropora plate cover remained low and confirmed that corals that lost all their tissue due to WS did not recover. These results demonstrate that WS represents a significant and selective form of coral mortality and highlights the serious threat WS poses to coral reefs in the Indo-Pacific.

No MeSH data available.