Outlook Online 2009

Recovery of coral reefs after crown-of-thorns starfish outbreaks

Australian Institute of Marine Science, 2008:

Wheeler Reef

"Wheeler Reef has been surveyed using manta tow 13 times since 1983, when it was classified as No Outbreak. Active Outbreak levels of COTS were first observed in 1985 and persisted through to 1989, with the population size peaking in 1988. No COTS have been observed from 1990 to 2007 and the reef was reclassified as Recovering in 1991. Median reef-wide live coral cover dropped from a high level (31-50%) in 1986 to a low level (1-10%) in 1988. By 2003 coral cover had recovered to the high levels (31-50%) that were recorded prior to COTS outbreaks in the early 1980s. Wheeler Reef was reclassified from Recovering to No Outbreak in 1998. Reef-wide coral cover declined to a moderate level (21-30%) following the bleaching event of 1998. However, it recovered quickly and was recorded at a high level again in 2001. Surveys in 2007 showed median reef-wide coral cover remained high. No COTS coral bleaching or signs of black band disease were recorded in 2007. Signs of white syndrome affected a few scattered coral colonies around the reef perimeter. Wheeler Reef remained classified as No Outbreak in 2007."

COTS_Coral_Wheeler

Davies Reef

"Davies Reef has been surveyed extensively using manta tow since 1986, when it was originally classified as No Outbreak. Median reef-wide live coral cover was high (41-50%) in 1987. In 1988 COTS numbers increased and the reef was classified as an Active Outbreak. Reef-wide coral cover correspondingly had dropped to a moderate (11-30%) level. COTS numbers subsequently peaked in 1990 and had declined by 1993 when the reef was reclassified as Recovering. Despite decreased numbers of COTS, median reef-wide live coral cover remained moderate and it was not until 1998 that there was a noticeable increase to a high level (31-50%). Small numbers of COTS were observed in 1997 and 1998 but well below levels that should affect reef-wide live coral cover. Coral cover declined between 1999 and 2001 to a moderate level (11-30%) that persisted through to 2004. There was an increase in COTS activity between 2002 and 2005, which contributed to the small decline in reef-wide live coral cover to a moderate (11-20%) level in 2007. No COTS or signs of coral disease were recorded during surveys in 2007. The reef remained classified as Recovering."

COTS_Coral_Davies

John Brewer Reef

"John Brewer Reef has been surveyed using manta tow regularly since 1984, when it had an extremely large COTS population and the reef was classified as Active Outbreak. The COTS population subsequently declined and in 1987 the reef was reclassified as Recovering. Median reef-wide live coral cover persisted only at a low (1-10%) level from 1986 through to 1990 before beginning to show signs of recovery. In 1993 reef-wide live coral cover had increased to moderate (11-30%) levels and by 1998 reef-wide live coral cover was at high levels (31-50%). Surveys in 2001 recorded high COTS numbers and the reef was reclassified as Active Outbreak. COTS remained at outbreak levels through to 2003 and there was a corresponding drop in coral cover to a very low (1-5%) level. Coral cover has persisted at this low level through to the latest surveys in 2008. The reef was reclassified as Recovering in 2004 and retained this classification in 2008. No COTS, coral bleaching or signs of disease were observed during manta tow surveys in 2008."

COTS_Coral_John_Brewer

Lizard Island

"Lizard Island Reef has been surveyed regularly using manta tow since 1986 when it was considered Recovering from previous COTS activity. From 1996 until 1998 the reef was classified as Active Outbreak and there was a corresponding decline in median reef-wide live coral cover to a very low (1-5%) level. The reef was reclassified as Recovering in 1999 and coral has generally remained low (1-10%) since this time. This lack of recovery is likely due to small numbers of residual COTS that have been observed on this reef over succeeding years. Surveys since 2004 indicate some recovery with median reef-wide live coral cover at a moderate level (10-20%) recorded in 2007 and 2008. Small numbers of COTS were observed in 2007 with increased numbers observed in 2008 but well below outbreak levels. Lizard Island Reef remains classified as Recovering. Low level bleaching and signs of black band disease restricted to small numbers of individual colonies were observed on the back and front of this reef in 2008. Signs of white syndrome disease were restricted to a few scattered coral colonies on the back, northern flank and front of the reef but absent from the rest of the reef. Lizard Island Reef remains classified as Recovering."

COTS_Coral_Lizard

Hardy Reef

"Hardy Reef has been surveyed 15 times since 1986 when it had high reef-wide live coral cover (30-50%) and was classified as No Outbreak. An outbreaking population of COTS developed between 1986 and 1989, resulting in a sharp decline in coral cover. The coral then recovered and reef-wide live coral cover remained high in subsequent years despite an Incipient Outbreak in 1992. Between 1993 and 1997 coral cover once again declined with a sharp drop recorded in 1997, most likely due to Cyclone Justin. Reef-wide live coral cover has increased gradually since 1997 and remains moderate (10-30%) in 2004. COTS were observed during surveys in 2004 but in numbers well below those expected to cause significant coral damage. Bleaching and white syndrome disease was restricted to a few scattered colonies during surveys in 2004 with the exception of the second flank where coral bleaching affected up to 5% of total hard coral cover."

COTS_Coral_Hardy


Citation and/or URL

 http://data.aims.gov.au/waReefPage/servallreefs 

Spatial Coverage

 Reef-wide

Temporal Coverage

 1986 to present

Update Frequency

Surveys took place every year from 1986-2006 and every other year from 2006 to present. 

Other Information

None

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