AS ocean temperatures continue to rise in the Great Barrier Reef this summer, scientists from James Cook University (JCU) have reported areas of moderate to severe coral bleaching offshore from Rockhampton.
The bleaching was observed during routine surveys conducted as part of a 25-year program tracking changes in fish communities and coral reef habitats at 42 Great Barrier Reef islands, which are highly valued and frequented by tourists, recreational fishers, and local communities.
Dr Maya Srinivasan from JCU’s Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) expressed concern over the unprecedented warmth of the water which reached 29°C during multiple days of surveys.
“Once we were in the water, we could instantly see parts of the reef that were completely white from severe bleaching – some corals were already dying,” Dr Srinivasan stated.
Heat stress is the primary cause of coral bleaching and severely bleached corals may die if the water temperature remains higher than normal for too long. However, they can recover if ocean temperatures stabilize.
The team surveyed 27 sites at the Keppel Islands, with most sites showing signs of bleaching, and only deeper areas of reefs relatively unimpacted by heat stress.
“While some corals were already dying, many could recover if the water cools in the coming weeks, and we did see temperatures begin to drop towards the end of the trip,” Dr Srinivasan said.
The Keppel Islands, a highly visited island group in the Great Barrier Reef, have seen coral reefs and fish communities recover from past bleaching events but prolonged heat stress poses a threat to their resilience.
Dr Srinivasan highlighted the vulnerability of island reef habitats, especially inshore locations, making them more susceptible to impacts like water quality issues, coral bleaching, and overfishing.
The team will now survey reefs in the far northern Great Barrier Reef and other locations impacted by recent floods, gathering data to understand recovery rates and fish population dynamics.
The monitoring program, funded by the Australian Government’s #ReefTrust and the Great Barrier Reef Foundation, aims to provide insights into reef health and inform targeted intervention and management strategies to preserve this vital ecosystem.
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