Sweatman et al. 2008:

"Coral cover, the number of COTS per reef and the average number of COTS per tow are used to assess the outbreak status of each reef (Fernandes 1991; Moran and De'ath 1992). There are four categories: Active Outbreak (AO), Incipient Outbreak (IO), Recovering (RE), or No recent Outbreak (NO). An Active Outbreak occurs when starfish densities reach levels where loss of coral tissue through starfish feeding is estimated to be faster than the growth of coral. Definitions of outbreaks have evolved over the time that surveys have been made. Initially, reefs with active outbreaks were those where >40 COTS were recorded over the whole reef perimeter and >30% of hard coral was dead. An examination of manta tow data from reefs of all categories found that 90% of reefs with active outbreaks by these criteria supported >1500 COTS km^-2 (Moran and De'ath 1992). This corresponds to approximately 0.22 COTS per two-minute tow. After consideration of the relative costs of Type I and Type II errors, the criterion for an Active Outbreak was revised upwards to 1.0 COTS per tow (Lassig and Engelhardt 1995), Engelhardt et al. 1997). This represents a starfish density that is highly likely to cause net decline in corals. In this report the criterion of 0.22 COTS per tow is referred to as "Incipient outbreak" level."

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Citation and/or URL

 Sweatman, H., Cheal, A.J., Coleman, G.J., Emslie, M.J., Johns, K., Jonker, M., Miller, I.R. & Osborne, K. 2008, Long-term monitoring of the Great Barrier Reef: status report, Australian Institute of Marine Science 8, Townsville.

Spatial Coverage

 Reef wide

Temporal Coverage

 1986 to present

Update Frequency

 Annual

Other Information

 None