Back from the Reef: December 2023

Hi Everyone,

The AIMS Long-term Monitoring Program have recently completed the third survey trip of the 2023/24 reporting year. The latest round of surveys were from 18 reefs in the Cooktown/Lizard Island, Princess Charlotte Bay, and Cape Grenville sectors of the northern Great Barrier Reef during November to December 2023.

View our reef dashboard at the online reporting platform. Archived sector reports are available from the old survey reports page. Previous Back from the Reef emails are also available: Oct 2023 (Capricorn-Bunkers and Swains), Sept 2023 (Cairns and Innisfail), March 2023 (Cairns, Innisfail and Townsville), February 2023 (Whitsundays and Pompeys).

Cooktown/Lizard Island Sector

Dates: 17 November to 20 November, 2023

Three reefs were surveyed in the Cooktown/Lizard Island sector: North Direction Island, Macgillivray Reef, and Lizard Isles.

Although no crown-of-thorns starfish (COTS - Acanthaster cf. solaris) were observed on manta tow in this sector, scars were observed on all surveyed reefs.

Live hard coral cover increased on all of these reefs compared to the previous survey. However, all reefs remained within their range of coral cover from the 2022-23 surveys.

Minor levels (<5%) of bleaching were recorded on two reefs. These levels are in line with observations in previous surveys during summer.

The results of manta tow surveys are available on the reef pages at the reef monitoring platform. Results from fixed site surveys of corals and reef fishes will become available following completion of QA/QC and image analyses.

Map showing the location of the Cooktown/Lizard Island sector, of which three reefs were surveyed in November 2023.

Table 1: Summary of manta tow surveys of reefs in the Cooktown/Lizard Island sector surveyed in November 2023. Arrows indicate the trend in live coral cover and Acanthaster cf. solaris (COTS) numbers since last survey; ▲ = increase, ▼ = decrease, " " = no change. COTS outbreak status: NO = No Outbreak. Tows relates to the reef perimeter.

Image 1: Ostracion cubicus above the north-eastern flank of Lizard Isles in the Cooktown/Lizard Island sector of the Great Barrier Reef. Many small tabulate colonies of hard coral are growing on the reef pavement, showing evidence of recovery following multiple disturbances in the past decade.

Image 2: A view of the south-western flank of Macgillivray Reef in the Cooktown/Lizard Island sector of the Great Barrier Reef. The reef slope is dominated by hard corals with tabulate growth forms.

Princess Charlotte Bay Sector

Dates: 21 November to 4 December, 2023

Six reefs were surveyed in the Princess Charlotte Bay sector: Davi e Reef, Reef 13-124, Corbett Reef, Rodda Reef, Tydeman Reef, and Sand Bank No. 1 Reef. This completes surveys in the Princess Charlotte Bay sector for 2023-24.

Although no COTS were observed in this sector, scars were observed on three reefs.

Live hard coral cover increased on five reefs and decreased on one reef. However, most reefs remained within the range of coral cover of their previous surveys, and only two increased significantly.

Minor levels (<5%) of bleaching were recorded on four reefs. These levels are in line with observations in previous surveys during summer.

Map showing the location of the Princess Charlotte Bay sector, of which six reefs were surveyed in November to December 2023.

Table 2: Summary of manta tow surveys of reefs in the Princess Charlotte Bay sector. Arrows indicate the trend in live coral cover and Acanthaster cf. solaris (COTS) numbers since last survey; ▲ = increase, ▼ = decrease, " " = no change. COTS outbreak status: NO = No Outbreak. Tows relates to the reef perimeter.

Image 3: A view of Davie Reef in the Princess Charlotte Bay sector of the Great Barrier Reef, with a diverse fish community and high cover of hard corals in a variety of growth forms including digitate, tabulate and submassive.

Cape Grenville Sector

Dates: 24 November to 2 December, 2023

Nine reefs were surveyed in the Cape Grenville sector: Reef 11-162, Monsoon Reef, McSweeney Reef, Reef 11-049, Pearson Reef, Middle Banks 2, Middle Banks 3, Mantis Reef, and Lagoon Reef. This completes surveys in the Cape Grenville sector for 2023-24.

Low numbers of COTS were observed on two reefs, but these numbers were below the threshold of a Potential Outbreak (0.1 COTS per tow). COTS scars were also observed on four other reefs.

Live hard coral cover increased on eight surveyed reefs and decreased on one reef. However, most reefs remained within the range of coral cover of their previous surveys, and only three increased significantly.

Five reefs had low levels of coral bleaching (<5% of corals), and these levels are in line with observations in previous surveys during summer. However, bleaching levels up to 20% of corals were recorded on some sections of Lagoon Reef, indicating an early onset of heat stress in some areas of the sector.

Map showing the location of the Cape Grenville sector, of which nine reefs were surveyed in November to December 2023.

Table 3: Summary of manta tow surveys of reefs in the Cape Grenville sector. Arrows indicate the trend in live coral cover and Acanthaster cf. solaris (COTS) numbers since last survey; ▲ = increase, ▼ = decrease, " " = no change. COTS outbreak status: NO = No Outbreak. Tows relates to the reef perimeter.

Image 4: A view of Middle Banks 2 in the Cape Grenville sector of the Great Barrier Reef, with high cover of hard coral dominated by branching Porites.

News and stories from AIMS

Seabird droppings may help corals recover faster from climate change-driven disturbances

Nutrients in seabird droppings are boosting coral growth rates in a remote reef system and helping them bounce back quicker from disturbances like bleaching, a new study has found.

Traditional knowledge exchange to create a framework for Pacific reef monitoring

AIMS scientists are working with Australia’s Gidarjil Development Corporation, Papua New Guinea’s Sea Women of Melanesia (SWoM), the Samoan Government and community, the Secretariat for the Pacific Regional Environmental Programme (SPREP), and Conservation International, to develop a coral reef monitoring framework for Pacific nations.