Summary
- 11 reefs were surveyed in the Princess Charlotte Bay sector.
- Sector-wide hard coral cover was moderate (10- 30%) and had increased since 2020.
- Hard coral cover had increased on nine reefs and had declined on two reefs.
- Elevated levels of white syndrome were observed on Rodda Reef.
- No crown-of-thorns starfish (COTS) were recorded.
- Low levels of hard coral bleaching were observed.
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. Click the points for more information.
Table 1: Overview of results obtained from manta tow surveys of reefs in the Princess Charlotte sector
| Princess Charlotte Bay Sector | Summary | Trend since last survey |
|---|---|---|
| Average Coral Cover (%) | 27.6 | Increased |
| COTS status: | No Outbreaks | Stable |
| Coral bleaching: | Low | Stable |
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 11 reefs were surveyed in the Princess Charlotte Bay sector of the Great Barrier Reef (GBR) (Fig 1).
Preliminary results of the manta tow surveys are presented in Tables 1 and 2. The overall median hard coral cover for the sector was moderate (10-30%) (Table 1) (Fig 2) and had increased since previous surveys in 2020 (Fig 2).
Hard coral cover was high (30 to 50%) on five reefs and moderate (10-30%) on six reefs. (Table 2). Since the previous surveys hard coral cover had increased on nine reefs and declined on two reefs (Table 2).
There were no COTS recorded during manta tow surveys (Table 2). Sector-wide numbers of COTS remained stable since previous surveys (Table 1, Fig 2).
Low levels of coral bleaching were recorded at four reefs, restricted to scattered individual colonies.
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 Long-Term Monitoring Program can be found on the AIMS website.
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. Outbreak Status: NO no outbreak, PO potential outbreak >0.1 COTS per tow, IO incipient outbreak >.22 COTS per tow, RE recovering, AO = Active Outbreak>1 COTS per tow.
| Reef | Shelf Position | Tows | Previous survey year | Total A. solaris per reef | A. solaris per tow | A. Solaris Outbreak Status | Live Hard Coral Cover % | Soft Coral Cover % | Survey Year |
|---|---|---|---|---|---|---|---|---|---|
| 13063S | Mid | 62 | 2002 | 0 | 0 ▼ | NO | 13.8 ▼ | 3.2 ▼ | 2021 |
| 13124S | Mid | 58 | 2020 | 0 | 0 ▼ | NO ▼ | 23.5 ▲ | 9.3 ▲ | 2021 |
| 13040S | Outer | 45 | 2020 | 0 | 0 | NO | 31.4 ▲ | 5.8 ▲ | 2021 |
| 13121S | Outer | 33 | 2019 | 0 | 0 | NO | 21.5 ▲ | 6.9 ▲ | 2021 |
| CREECH REEF (NORTH) | Outer | 36 | 2020 | 0 | 0 | NO | 39.7 ▲ | 6.6 ▲ | 2021 |
| DAVIE REEF | Outer | 44 | 2020 | 0 | 0 | NO | 32 ▲ | 3.8 ▲ | 2021 |
| RODDA REEF | Outer | 36 | 2019 | 0 | 0 | NO | 37.5 ▲ | 9.1 ▲ | 2021 |
| SAND BANK NO 1 REEF | Outer | 45 | 2020 | 0 | 0 | NO | 33.5 ▲ | 8.5 ▲ | 2021 |
| TYDEMAN REEF | Outer | 65 | 2005 | 0 | 0 | NO | 22 ▼ | 3.8 ▲ | 2021 |
| CORBETT REEF | Mid | 97 | 2020 | 0 | 0 | RE | 23.9 ▲ | 2.5 ▲ | 2021 |
| SAND BANK NO 8 REEF | Outer | 35 | 2019 | 0 | 0 | NO | 23.7 ▲ | 5.1 ▲ | 2021 |
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 dense school of Trevally swim along the reef flank at Corbett Reef.
Image 2. The northern flank of Rodda Reef had a steep drop-off, with the top and crest covered in large Acropora plates.
Image 3. The sand cay at Davie Reef populated with nesting seabirds.
Image 4. A Queensland grouper swimming with numerous pilot fish at Reef 13124S.
