Summary
- 4 reefs were surveyed in the Innisfail sector.
- Sector-wide hard coral cover was moderate (10-30%) and has increased slightly since 2020.
- Hard coral cover had increased on two reefs, declined on one reef and was stable on the remaining reef.
- No crown-of-thorns starfish (COTS) were recorded.
- Low levels of hard coral bleaching were observed on one reef.
Hard Coral Cover 0-10% 10-30% 30-50% 50-75% 75-100%
Figure 1: Map showing location of reefs in the Innisfail sector. Click the points for more information.
Table 1: Overview of results obtained from manta tow surveys of reefs in the Innisfail sector
| Innisfail Sector | Summary | Trend since last survey |
|---|---|---|
| Average Coral Cover (%) | 13.1 | Increased |
| COTS status: | No Outbreaks | Stable |
| Coral bleaching: | Low | Decreased |
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 4 reefs in the Innisfail 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 slightly since previous surveys in 2020 (Fig 2).
Hard coral cover was moderate (10-30%) on all four reefs (Table 2). Since the previous surveys, hard coral cover had increased on two reefs, decreased at one reef and was stable on the remaining reef (Table 2).
No COTS were recorded at any reef during manta tow surveys (Table 2). Sector-wide numbers of COTS were low and stable since previous surveys (Table 1, Fig 2).
Low levels of coral bleaching were recorded at one reef, 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 Innisfail 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 |
|---|---|---|---|---|---|---|---|---|---|
| MOORE REEF | Mid | 80 | 2020 | 0 | 0 | NO | 13.2 ▲ | 10.1 ▲ | 2021 |
| SCOTT REEF | Mid | 68 | 2009 | 0 | 0 | NO | 10.9 ▼ | 5.9 ▼ | 2021 |
| FEATHER REEF | Mid | 45 | 2020 | 0 | 0 | NO | 15.2 ▲ | 6 ▲ | 2021 |
| WARDLE REEF | Outer | 58 | 2017 | 0 | 0 | NO | 11.6 | 9.9 ▲ | 2021 |
Figure 2: - Sector-wide changes in coral cover and the numbers of A. solaris for survey reefs in the Innisfail sector of the GBR. Orange trend line = Hard coral. Purple bars = Crown-of-thorns (COTS)
Image 1. Steep headed parrotfish cavort on the reef slope at Wardle Reef. Hard coral cover was moderate at this reef following declines due to crown-of-thorns starfish outbreaks.
Image 2. There were some sections of reef where coral cover was high, with abundant table Acropora colonies, like this section of Moore Reef.
Image 3. An abundance of large fishes on Scott Reef, despite only moderate coral cover. Many of the fishes seen here are not directly dependent on live hard coral cover, but rather require habitat complexity with crevices, nooks and crannies in which to shelter.
