Summary
- 12 reefs were surveyed in the Cape Upstart sector.
- Sector-wide hard coral cover was moderate (10- 30%) and had increased since the most recent survey year, 2018.
- Of the 12 reefs surveyed in 2021 the previous survey date varied from 2004 to 2018.
- Hard coral cover had increased on ten reefs and had declined on two reefs.
- Low numbers of crown-of-thorns starfish (COTS) were recorded on three reefs.
- 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 Cape Upstart sector. Click the points for more information.
Table 1: Overview of results obtained from manta tow surveys of reefs in the Cape Upstart sector
| Cape Upstart Sector | Summary | Trend since last survey |
|---|---|---|
| Average Coral Cover (%) | 26.3 | Increased |
| COTS status: | No Outbreaks | Stable |
| Coral bleaching: | Low | Increased |
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 12 reefs were surveyed in the Cape Upstart 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 2018 (Fig 2).
Hard coral cover was high (30-50%) on four reefs, and moderate (10-30%) on seven reefs and low (0-10%) on one reef. (Table 2). Since the previous surveys hard coral cover had increased on ten reefs and declined on two reefs. (Table 2).
Sector-wide numbers of COTS remained stable since previous surveys (Table 1, Fig 2). Low numbers of COTS were observed on three reefs (Table 2).
Low levels of coral bleaching were recorded at nine 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 Cape Upstart 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 |
|---|---|---|---|---|---|---|---|---|---|
| HOLBOURNE ISLAND REEF | Inner | 21 | 2004 | 0 | 0 | NO | 8.8 ▼ | 7.1 ▼ | 2021 |
| BOWDEN REEF | Mid | 77 | 2018 | 2 | 0.03 ▼ | NO | 29.7 ▲ | 3.3 ▼ | 2021 |
| CHARITY REEF | Mid | 33 | 2007 | 0 | 0 | NO | 16.5 ▲ | 3.7 ▼ | 2021 |
| ELIZABETH REEF | Mid | 36 | 2015 | 0 | 0 | NO | 26.2 ▲ | 13.5 ▲ | 2021 |
| FAITH REEF | Mid | 34 | 2015 | 3 | 0.09 ▲ | NO ▲ | 26.7 ▲ | 6.1 | 2021 |
| HOPE REEF(19046) | Mid | 30 | 1992 | 0 | 0 | NO | 19.9 ▼ | 7.7 ▼ | 2021 |
| SHELL REEF | Mid | 25 | 2007 | 1 | 0.04 ▼ | RE ▼ | 35.4 ▲ | 7.2 ▲ | 2021 |
| SHRIMP REEF | Mid | 61 | 2007 | 0 | 0 ▼ | NO | 30.3 ▲ | 4.9 ▲ | 2021 |
| WANSFELL REEF | Mid | 48 | 2005 | 0 | 0 | NO | 22.8 ▲ | 14.6 ▲ | 2021 |
| JACQUELINE REEF | Outer | 64 | 2015 | 0 | 0 | NO | 28.1 ▲ | 5.4 ▲ | 2021 |
| JAGUAR REEF | Outer | 38 | 2002 | 0 | 0 | NO | 36.5 ▲ | 3.4 ▼ | 2021 |
| VIPER REEF | Outer | 29 | 2011 | 0 | 0 | NO | 49.3 ▲ | 2.9 | 2021 |
Figure 2: - Sector-wide changes in coral cover and the numbers of A. solaris for survey reefs in the Cape Upstart sector of the GBR. Orange trend line = Hard coral. Purple bars = Crown-of-thorns (COTS)
Image 1. Levels of coral bleaching in Cape Upstart were low but isolated colonies of bleaching in sensitive species was observed such as these Goniastrea at Elizabeth Reef.
Image 2. High cover of Acropora coral at Faith Reef.
Image 3. Branching Acropora on the back of Viper Reef is an indication that bleaching impacts have not been severe in recent years.
Image 4. A white tip reef shark cruising along the slope at Jacqueline Reef.
