Abbot Point

We survey transects (paths) across each of the two island communities in the Abbot Point region, both pre- and post-wet season. At each transect, benthic (seafloor) cover is classified into categories of cover type and provides information on the dominant reef structure (hard or soft), as well as the extent of macroalgae, which can impede the growth of corals. Information on the extent of bleached, diseased or damaged corals is also determined, which provides information on the health of the coral community. Click below on each site.

Monitoring Locations
Camp Island

  • Camp Island is dominated by macroalgae, with levels consistently above 30%. Hard coral cover, while largely unaffected by TC Debbie with only small losses was severely impacted by a mass bleaching event in 2020; decreasing hard coral by 54% from October 2019 to June 2021. Hard coral cover has started to significantly increase as of May 2022, since the 2020 bleaching event.

    Mean percentage of Benthic Composition

    Download Data More Info

  • The 2020 major bleaching (almost 40% of hard corals) due to the accumulated heat stress has not occurred since at the same scale despite some prolonged warmer periods during both 2021 and 2022 summers. Sediment found on hard coral colonies during surveys has increased since monitoring began but subsequent damage has yet to be observed as a result. Damage from predation and disease, whilst low levels, has been consistently recorded.

    Mean density of affected coral colonies per 40 square metres

    Download Data More Info
Holbourne Island

  • Holbourne Island has comparatively very low macroalgae cover and on average double the hard coral cover of Camp Island; however, TC Debbie was shown to have had a devastating impact on coral cover, with a loss of more than 75% of coral cover. Recovery of these communities remains, to-date, negligible. In 2020 sample sites were adjusted to monitor more active community sites, where hard coral has since shown stability and progressive increases.

    Mean percentage of Benthic Composition

    Download Data More Info

  • The major regional scale bleaching event in early 2020 led to significant bleaching of Holbourne Island hard coral communities but to a lesser extent than at Camp Island; likely in part due to the slightly deeper sites at this location. Following the same trends as Camp Island, Holbourne corals also have an increased pattern of sediment found on corals, some predation and disease but with little measurable damage as a result.

    Mean density of affected coral colonies per 40 square metres

    Download Data More Info
1. Please note y-axis max differs between indicators of health and benthic composition charts.2. SEs (standard errors) can be accessed in the full reports on our reports and research page.3. Indicators of health chart represents pre-wet survey dates only, full survey data can be found in reports download4. Note: Small sponge readings up to approx 0.3 % may not be visible. Please refer to the downloadable data file.

Coral and Benthos Cover at Abbot Point

Inshore corals and benthic (seafloor) cover are, to an extent, naturally acclimatised to greater frequency and scale of disturbances like cyclones, high water temperatures, and freshwater influx and elevated turbidity (sediment in water) from flooding compared to their more offshore counterparts. Measuring coral cover, alongside diversity, juvenile recruitment, and bleaching and disease, can help us to understand the typical degree of change in these communities, anticipate recovery potential and timeframes from such disturbances.

What the chart shows

Surveys at Abbot Point commenced in 2016. A clear impact from Tropical Cyclone Debbie was shown 18 months later at Holbourne Island, which was most affected, given the cyclone's trajectory. Holbourne Island has struggled to recover from these impacts and has also been predated consistently by crown-of-thorns starfish.

Holbourne Island sites were revised in 2020 and therefore trends shown are not temporally comparable. Nonetheless, changes observed since October 2020 show stable hard coral cover at all Holbourne Island sites.

Camp Island hard coral communities, however, were somewhat protected by the angle of approach of Tropical Cyclone Debbie and showed strong recovery since 2017. The 2020 summer bleaching event however was found to significantly affect corals at all sites, with close to 40% of corals bleached and a high percentage of mortality at Camp Island (cover reduced from 24% to 6% from October 2019 to October 2020). Signs of recovery at Camp Island have since been observed however cover is still significantly below levels seen in 2019.

You can see more analysis on the data in these reports.

Hard coral cover at Abbot Point

1. Please note y-axis is dynamic and therefore differs between each tab.2. SEs (standard errors) can be accessed in the full reports on our reports and research page.

What the chart shows

Surveys at Abbot Point commenced in 2016. A clear impact from Tropical Cyclone Debbie was shown 18 months later at Holbourne Island, which had approximately 14% soft coral cover prior to this and has struggled to recover, most recently recording 5% soft coral cover.

Camp Island communities however have never recorded high percentages of soft corals, covering less than 1%.

You can see more analysis on the data in these reports.

Soft coral cover at Abbot Point

1. Please note y-axis is dynamic and therefore differs between each tab.2. SEs (standard errors) can be accessed in the full reports on our reports and research page.

What the chart shows

Holbourne Island is a more mid-shelf location than Camp Island. In part due to its location, Holbourne Island has never shown levels of macroalgae >1%. Cover during the most recent pre-wet surveys was 0.75%.

Camp Island, by comparison, has consistently had much higher macroalgae cover, 36% during the same recent survey period. These high macroalgae levels are thought to be influenced by seasonal nutrient fluctuations. The peak of 76% in October 2020 followed the GBR region-wide accumulated heat stress event of early 2020. In the Mackay and Hay Point region macroalgae was seen over this same period to decline significantly except for Sargassum spp., the predominant macroalgae at Camp Island.

While Camp Island coral communities have historically been more susceptible to the stress-related bleaching from high water temperatures and competition for space with macroalgae, the main influences on coral health at Holbourne Island are predation by sea snails (Drupella) and crown-of-thorns starfish.

You can see more analysis on the data in these reports.

Macroalgae cover at Abbot Point

1. Please note y-axis is dynamic and therefore differs between each tab.2. SEs (standard errors) can be accessed in the full reports on our reports and research page.