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Parts of the Great Barrier Reef show the highest coral cover in 36 years



Coral is a vital part of many marine ecosystems, and it has faced significant challenges in recent centuries, especially in Australia’s Great Barrier Reef. However, a recent study has found that areas of the Great Barrier Reef currently show the greatest hard coral cover in 36 years, meaning coral populations are growing back even in the wake of various threats proving just how resilient coral reefs can be.


According to the Australian Institute of Marine Science (AIMS) annual report, the northern and central areas of Australia’s Great Barrier Reef show the highest level of hard coral cover since they began monitoring the reef's health in 1985. Hard coral cover refers to the proportion of a reef’s surface that is covered by live, stony corals which are the main contributors to a reef’s structure. Hard coral cover is a good measure of the health of coral reefs. In the northern region of the Great Barrier Reef, the average hard coral cover went from a low of 13% in 2017 to 36% in 2022. In the central area, the average hard coral cover went from 12% in 2019 to 33% in 2022. However, the hard coral cover in the southern region has decreased from 38% in 2021 to 34% in 2022 due to crown-of-thorn starfish outbreaks. With the exception of the southern region, the increase in hard coral cover in recent years is a good sign as it shows recovery has taken place in the reefs in the wake of four mass bleaching events in the last seven years.


According to AIMS monitoring program leader Mike Emslie, “What we’re seeing is that the Great Barrier Reef is still a resilient system. It still maintains that ability to recover from disturbances, but the worrying thing is that the frequency of these disturbance events is increasing, particularly the mass coral bleaching events.” As previously mentioned in our June Newsletter, bleaching is a natural stress response in the coral where it loses symbiotic algae and pigments, causing it to turn white and potentially die. Bleaching is caused by stress such as heat and a mass bleaching event is when bleaching is widespread throughout coral in a reef. The findings of AIMS show promise that coral is able to recover from significant disturbances but the increasing frequency of these bleaching events may pose a threat in the future.


Coral reefs play a vital role in maintaining marine ecosystems and biodiversity, and Australia’s Great Barrier Reef is perhaps the best example of this considering the many diverse marine organisms that call this reef home. However, due to heat stress from climate change, and other threats such as frequent mass bleaching events, wave damage, and predators like crown-of-thorn starfish, the Great Barrier Reef is still increasingly vulnerable. By annually monitoring the Great Barrier Reef, the Australian Institute of Marine Science hopes to discover long-term trends in the condition of coral communities across the reef that can help them to better protect this reef and its marine inhabitants. For now, the increased hard coral cover can be seen as a sign of hope, resilience, and recovery within the Great Barrier Reef.


Citations

1)“Parts of Australia’s Great Barrier Reef show highest coral cover in 36 years” NBC. https://www.nbcnews.com/news/world/great-barrier-reef-highest-coral-cover-36-years-australia-rcna41464

2) “Parts of Australia’s Great Barrier Reef Show Highest Coral Cover in 36 Years” US News.

https://www.usnews.com/news/world/articles/2022-08-03/parts-of-australias-great-barrier-reef-showhighest-coral-cover-in-36-years

3) “Highest coral cover in central, northern reef in 36 years” Australian Institute of Marine Science.

https://www.aims.gov.au/information-centre/news-and-stories/highest-coral-cover-central-northern-reef36-years

4) “Coral Cover” Healthy Reefs.

https://www.healthyreefs.org/cms/healthy-reef-indicators/coral-cover/


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