Report on surveys of the Swain sector of the Great Barrier Reef
· Most reefs in this sector remain to be surveyed in this reporting year.
Hard Coral Cover 0-10% 10-30% 30-50% 50-75% 75-100%
Figure 1: Map showing location of reefs in the Swain sector.
Table 1: Overview of results obtained from manta tow surveys of reefs in the Swain sector
As part of the Long Term Monitoring Program (LTMP), manta tow surveys of coral cover and the abundance of the coral feeding crown-of-thorns starfish (COTS), Acanthaster cf. solaris* were completed on two reefs, Reef 21-245 and Reef 21-278, in the Swain sector of the Great Barrier Reef. The preliminary results of the manta tow surveys are presented in Table 1. Median reef-wide live coral cover (coral cover) had increased at Reef 21-245 and remained stable at Reef 21-278. Low numbers of COTS (below outbreak levels) were recorded from Reef 21-245.
Scuba surveys of fixed transects were conducted at both reefs and recorded no COTS or coral bleaching. For both reefs cases of disease and numbers of the corallivorous snail, Drupella spp. were within the range of past values recorded from reefs within this region.
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 Swain 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.
Dates: 10th September – 1st October 2019
Vessel: RV Cape Ferguson
Survey leader: Ian Miller
Details of the manta tow method and results can be found here.
Click here for further details of the monitoring program design, sampling methods and a full explanation of the A. solaris outbreak terminology.
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