North Reef corals 2006 to 2022

Jiigurru (Lizard Island) is one of the best studied reef systems on the Great Barrier Reef, because the Australian Museum's Lizard Island Research Station has been operating there since the late 1970's. The whole island is within a Marine Protected Area, and there is detailed information on the coral community dynamics at multiple locations and spanning several decades. Coral Sea Foundation scientists have been monitoring the populations of corals and giant clams at Lizard Island since the mid 1980's.

Coral cover around Lizard Island has generally been high throughout this time, apart from a Crown of Thorns seastar outbreak in the mid 1990's. However, starting in April 2014, Lizard Island suffered 3 major disturbance events back-to-back over 3 years:
- Cyclone Ita (April 2014)
- Cyclone Nathan (March 2015)
- Strong coral bleaching event (early 2016).

Both cyclones were category 4, and the storm cores passed close to the island, with winds above 200km/h. There was extensive physical damage at exposed sites, with delicate corals broken and even large multi-ton heads of boulder coral (Porites) rolled around on the reef slopes. The 2016 bleaching event was the most severe recorded on the GBR since European occupation, and Lizard Island was right at the epicenter of the worst-hit region, with extensive coral mortality seen in the remaining branching corals that had survived the cyclones.
The important point is that virtually all the adult colonies of branching Acroporid corals around Lizard Island, and indeed most of the nearby reefs within 100km, were killed. So from the perspective of reef resilience, this situation produced a complete reset of the coral community, as only the toughest of the tough corals survived.
Despite these cumulative impacts, our surveys in mid 2016 and mid 2017 showed the recovery process was already underway, with recruitment of juvenile Acroporid corals observed at several sites around Jiigurru, including North Reef.
Subsequent photo surveys in 2018, 2019, 2021 and 2022 have revealed extremely rapid growth rates in these juvenile corals, and the image time series now provides a unique insight into the dynamics of reef recovery after severe disturbance.
As the Great Barrier reef faces a future with more frequent and more severe bleaching events, there has never been a greater need for regular scientific monitoring in order to understand the complex patterns of disturbance and recovery in this incredible ecosystem.
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