Summary
- Fourteen reefs were surveyed in this sector
- Sector-wide hard coral cover was moderate.
- Eight reefs were previously surveyed in January 2019; hard coral cover had increased on seven reefs and was unchanged on one.
- Three previously unsurveyed reefs had low coral cover.
- Low levels of crown-of-thorns starfish were recorded at three reefs.
- Coral bleaching was widespread, but at low levels (scattered, individual colonies).
Hard Coral Cover 0-10% 10-30% 30-50% 50-75% 75-100%
Figure 1: Map showing location of reefs in the Princess Charlotte sector.
Table 1: Overview of results obtained from manta tow surveys of reefs in the Princess Charlotte sector/p>
| Princess Charlotte Bay Sector | Summary | Trend since last survey |
|---|---|---|
| Average Coral Cover (%) | 16.93 | Decreased |
| COTS status: | No Outbreaks | Stable |
| Coral bleaching: | Low | Decreased |
Table 2: Summary of manta tow surveys of reefs in the Princess Charlotte sector. Arrows indicate the trend in live coral cover and A. solaris since last survey; ▲ = increase, ▼ = decrease, " " = no change. A. solaris 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 | A. Solaris Outbreak Status | Live Hard Coral Cover % | Soft Coral Cover % | Survey Year |
|---|---|---|---|---|---|---|---|---|---|
| OSBORNE REEF | Inner | 41 | 2017 | 0 | 0 | NO | 3.48 ▼ | 2.62 ▼ | 2020 |
| 13124S | Mid | 62 | 2019 | 8 | 0.13 | NO | 20.54 ▲ | 4.71 ▼ | 2020 |
| 13040S | Outer | 49 | 2019 | 0 | 0 | NO | 16.55 ▼ | 4.48 ▲ | 2020 |
| CREECH REEF (NORTH) | Outer | 37 | 2019 | 0 | 0 | NO | 39.19 ▲ | 3.71 ▼ | 2020 |
| DAVIE REEF | Outer | 49 | 2019 | 0 | 0 | NO | 24.43 ▼ | 2.8 ▼ | 2020 |
| SAND BANK NO 1 REEF | Outer | 38 | 2019 | 0 | 0 | NO | 25.65 ▲ | 2.89 ▼ | 2020 |
| 13093A | Mid | 19 | 2013 | 0 | 0 | NO | 7.11 ▼ | 3.82 ▼ | 2020 |
| CORBETT REEF | Mid | 100 | 2019 | 0 | 0 | RE | 10.3 ▼ | 2.37 ▼ | 2020 |
| HEDGE REEF | Mid | 40 | 2013 | 0 | 0 | NO | 2.88 ▼ | 3 ▼ | 2020 |
Figure 2: - Sector-wide changes in coral cover and the numbers of A. solaris for survey reefs in the Princess Charlotte sector of the GBR. Orange trend line = Hard coral. Purple bars = Crown-of-thorns (COTS)
Image 1: A vibrant and diverse coral assemblage on the back of Creech Reef
Image 2: Humphead wrasse, red snapper, and diagonal-banded sweetlip swim among a school of steephead parrotfishes at Reef 13040.
Image 3: Evidence of severe mortality from the 2016/17 coral bleaching events at Osborne Reef. Turf algae covers most of the reef surface, with a few remaining massive corals interspersed among dead standing coral skeletons.
