Report on surveys of the Capricorn-Bunker sector of the Great Barrier Reef


Summary

  • Strong recovery in hard coral cover on most reefs since storms and Cyclone Hamish in 2008/09
  • Little evidence of significant impact of the 2016 bleaching event
  • One coral feeding crown-of-thorns starfish, Acanthaster planci observed at one reef

Figure 1 - Map showing location of reefs in the Capricorn-Bunker sector. Click on figure to visit AIMS Spatial Maps for information on individual reefs.

Capricorn-Bunker Sector 

Summary

Trend since last survey

Median Coral Cover:

High (30-50%)

Increased

COTS status:

No Active Outbreak

Decreased

Coral disease:

Overall Low

Increased

Coral bleaching:

Very Low

Decreased


As part of the Long Term Monitoring Program (LTMP), surveys of coral cover and abundance of the coral feeding crown-of-thorns starfish (COTS), Acanthaster planci, were completed on four reefs in the Capricorn-Bunker sector of the Great Barrier Reef (GBR) using the manta tow technique. Results (Table 1) showed that median reef-wide live coral cover (coral cover) had remained stable at two reefs and increased at two reefs, indicating strong recovery since storm damage in 2008/09.

A single A. planci was observed on one reef, Lady Musgrave Island. Small numbers of A. planci have been observed along the back reef at Lady Musgrave Island in previous surveys, but these have always been well below outbreak levels. Overall A. planci activity had declined in this sector compared to the last survey in 2015.

Surveys in 2017 recorded very low levels of coral bleaching, which was limited to scattered individual colonies on one reef (One Tree Island). There was no evidence of mortality from coral bleaching the previous summer. Although all reefs surveyed had a higher incidence of white syndrome coral disease since the previous surveys, levels were  low to moderate and no doubt reflect the increased cover of table and branching Acropora corals, which are known to be among the most susceptible corals to this disease. Higher than average incidence of brown-band coral disease was also observed at all the reefs surveyed 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. planci outbreak terminology can be found on the AIMS website
 

Table 1 - Summary of manta tow surveys of reefs in the Capricorn-Bunker sector. Arrows indicate the trend in live coral cover and A. planci since last survey; “”  = increase, “” = decrease, “  ” = no change.

Reef

Shelf Position

Tows

A. planci

A. planci per tow

Median Live Coral Cover

Median Dead Coral Cover

Median Soft Coral Cover

Reef Status

BROOMFIELD

Outer

47

0

0

40-50%

0%

0-5%

NO

LADY MUSGRAVE IS

Outer

69

1

0.01

30-40%

0-5%

0-5%

NO

ONE TREE IS

Outer

78

0

0

30-40%

0-5%

0-5%

NO

WRECK IS

Outer

45

0

0

50-63%

0%

0-5%

NO

Dates: 8th – 28th January 2017

Vessel: RV Cape Ferguson

Survey leader: Mike Emslie