Hay Point & Mackay
We survey transects (paths) across each of our island communities in the Mackay and Hay Point region, both pre and post-wet season. The inshore communities have been monitored since 2006. Keswick Island monitoring was also completed from 2015 until 2020. Data confirmed this location as more representative of mid-shelf reefs compared to inshore coral communities, the focus of our regular monitoring program. At each transect, benthic (seafloor) cover is classified into categories of cover type and provides information on the dominant reef structure (hard or soft coral), 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 monitoring location.
Four cyclone and extreme tropical low weather events impacted these inshore island locations in the years leading up to 2025. Read more on extreme weather impacts on the coral near our ports. In this same period, these locations have also experienced two GBR-wide bleaching events aligning with accumulated sea surface temperature peaks. More information on the broader reef health and coral bleaching is available at the Great Barrier Reef Marine Park Authority website.
1. 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 download.4. Small sponge readings up to approx 0.3 % may not be visible. Please refer to the downloadable data file. 5. An adjusted monitoring program design was implemented in Oct 2020 at Holbourne Island, resulting in a rearrangement of site locations to provide a more representative spread of coral cover and community assemblage. Pre-October 2020 results shown in graphs are therefore not directly comparable and may show increased variability in trends initially. Further details of these changes can be seen in the full reports.6. This same review (Oct 2022) resulted in a reduction from 6 to 4 sites per island for Hay Point and Mackay. Pre-October 2020 results shown in graphs will therefore not be directly comparable however this is not considered to have a measurable impact for the purpose of this display.7. Monitoring at Keswick Island ceased in 2020 after data confirmed this location as more representative of mid-shelf reefs compared to inshore coral communities.Coral and Benthic Cover at Hay Point & Mackay
Inshore corals and benthic (sea floor) 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
Over the past 12 months, hard coral cover has continued to increase in the three inshore locations following the major 2020 disturbance of accumulated sea surface temperature heat stress at the GBR-wide scale in 2020. This potential recovery is a positive outcome over only a few years following such a large-scale disturbance at these locations.
Over the last decade, hard coral cover has fluctuated with some losses across locations after both the 2017 TC Debbie and the 2020 heat stress event, however, recovery gains since then have held at both Round Top and Victor Island with 31% and 29% hard coral respectively. Slade Island, with 27% hard coral cover, is also showing good recovery since 2020 diebacks.
Read more on cyclone impacts on the coral near our ports. You can see more analysis on the data in these reports.
Hard coral cover at Hay Point & Mackay
What the chart shows
Soft corals have never been common in the inshore islands monitored (historically ranging from 2% to 10% of cover); however, they have consistently been significantly more abundant on Round Top and Keswick. Being a mid-shelf reef, Keswick has since been removed from the monitoring program however Round Top remains the most abundant for soft corals, these most recently accounting for 15% of cover.
This coverage represents an increase since the declines observed in 2020 that aligned with GBR region-wide accumulated sea surface temperature peaks. Slade and Victor Islands have also maintained small to minor increases, with cover most recently at 3.5% and 2.6% respectively. Read more on cyclone impacts on the coral near our ports. You can also see more analysis on the data in these reports.
Soft coral cover at Hay Point & Mackay
What the chart shows
The extreme cyclonic weather events over the last decade not only had significant effects on hard coral cover but also preceded a marked increase in macroalgae at all locations. In contrast, macroalgae at all locations declined during the 2020 region-wide accumulated heat stress event. Macroalgae at Round Top Island and Slade Island, while fluctuating seasonally, have since maintained significantly lower coverage.
From summer 2015 to 2025 macroalgae decreased from 24% to 0.96% on Round Top Island and similar coverage to the 2006 & 2007 baseline surveys. In contrast, while Victor Islet coverage has shown sharp reductions after cyclone or heat stress events, this rebounds with consistently higher coverage over time, increasing from 29% to 31% between 2015 and 2025.
You can see more analysis on the data in these reports.