Cementing coral reefs

Crustose coralline algae, or CCA, is an important part of what stabilises reef structures in changing conditions. To determine just how rising temperatures and ocean acidification affect CCA, researchers have deployed more than 144 'stations’ across 18 reefs. Designed from concrete blocks covered in settlement tiles, these inventive stations are monitoring how CCA calcifies and grows under differing environments. 

In the long-term, ocean acidification is likely to be a significant impact of a changing climate on the Great Barrier Reef ecosystem. As more carbon dioxide from the atmosphere is dissolved in the ocean, the water becomes more acidic. Among other impacts, this decreases the capacity of corals to build their skeletons which create important habitats for other marine life. But the impacts will vary greatly across different reef habitats and locations, hence the ability to monitor individual reefs and gain early feedback on changes is vital. Crustose coralline algae (CCA) are integral to coral reef growth and stabilisation. They also facilitate reef recovery by encouraging settlement of coral larvae. This research project investigated whether CCA can be used as an early warning system for changes in ocean chemistry and temperature.

• Pink in colour 

• Have a CaCO3 skeleton 

• They are diverse (and beautiful!) 

• Provide beneficial roles on the reef 

Two key roles:

1. they contribute significantly to reef calcification and cementation 

2. they induce larval settlement of many benthic organisms. 

• METHOD of developing a way to measure coralline algae calcification 

• MEASUREMENTS of coralline algae calcification along the Great Barrier Reef 

• MONITOR the Great Barrier Reef into the future to track impacts of climate change on the reef 

This research forms part of the foundational knowledge around the use of CCA as a metric and the ecological role it plays in the coral reef ecosystem.