Dates: 9th February– 3rd May 2019
- Manta tow surveys of two reefs were completed in the Pompey sector
- Creal Reef was recovering from a crown-of-thorns outbreak and coral bleaching
- Reef-wide coral cover at Credlin Reef declined due to multiple causes
Hard Coral Cover 0-10% 10-30% 30-50% 50-75% 75-100%
Figure 1: Map showing location of reefs in the Pompeys sector.
Table 1: Overview of results obtained from manta tow surveys of reefs in the Pompeys sector
|Pompeys Sector||Summary||Trend since last survey|
|Median Coral Cover||Moderate (10-30%)||Increased|
|COTS status:||No Outbreaks||Decreased|
As part of the Long Term Monitoring Program (LTMP), manta tow surveys of hard coral cover and the abundance of the coral feeding crown-of-thorns starfish (COTS), Acanthaster cf. solaris* were completed on two reefs in the Pompey sector of the Great Barrier Reef (GBR). Preliminary results of the manta tow surveys are presented in Tables 1 and 2.
While overall median reef-wide coral cover for the sector was moderate (10-30%) coral cover was had increased on one reef (Creal) and declined on the other (Credlin). The decline in coral cover on Credlin reef was attributed to the effects of Cyclone Debbie, a category 4 system that passed over the adjoining Whitsunday sector in 2017.
Details of the manta tow method can be found in the Standard Operational Procedure No. 9 [AIMS Research - Crown-of-thorns Starfish and Coral Surveys - Standard Operational Procedure 9]. Further details of the monitoring program design, sampling methods and a full explanation of the A. solaris outbreak terminology can be found on the AIMS website.
*Note: genetic studies show that there are at least four species of COTS. These are the North and South Indian Ocean species (A. planci and A. mauritiensis), a Red Sea species (not yet named) and a Pacific species. The range of the Pacific includes the Great Barrier Reef and it has been provisionally named Acanthaster solaris (Haszprunar et. al. 2017).
Table 2: Summary of manta tow surveys of reefs in the Pompeys sector. Arrows indicate the trend in live coral cover and A. solaris since last survey; ▲ = increase, ▼ = decrease, " " = no change. Outbreak Status: NO no outbreak, IO incipient outbreak >.22 COTS per tow, RE recovering, AO = Active Outbreak >1 COTS per tow.
|Reef||Shelf Position||Tows||Previous survey year||A. solaris||A. solaris per tow||Live Hard Coral Cover %||Soft Coral Cover %||Survey Year||Reef Status|
|CREAL REEF)||Mid||25||2017||0||0||23.99 ▲||0 ▼||2019||NO|
|CREDLIN REEFS (EAST))||Mid||53||2017||0||0||13.2 ▼||1.88||2019||NO|
Figure 2: - Sector-wide changes in coral cover and the numbers of A. solaris for survey reefs in the Pompeys sector of the GBR. Orange trend line = Hard coral. Purple bars = Crown-of-thorns (COTS)
Image 1. Submassive and digitate corals on the reef crest of Creal Reef. Submassive Isopora spp. hard corals are particularly susceptible to bleaching, so seeing them in abundance is a good sign.