Dead coral recruited to help keep the Great Barrier Reef alive
The changing climate is affecting all kinds of environments, but few places are harder hit than coral reefs. Australia's Great Barrier Reef in particular has suffered several severe coral die-offs in recent years, and its ultimate fate is looking pretty dire. Now, researchers from the University of Queensland have outlined a plan to recycle dead coral into structures that can help protect the remaining reef and promote new growth.
Nothing highlights the Great Barrier Reef's recent troubles like the back-to-back coral bleaching events that struck it in 2016 and 2017. With the waters only getting warmer, environmental experts predict that the frequency and severity of these events will only get worse in future, and although a recent study found that the reef has "died" five times in the last 30,000 years, the environment seems to be changing too fast for the coral to bounce back on its own this time.
Since this devastation is most likely our fault, it's our responsibility to help protect and restore the reef however we can. To that end, scientists have proposed altering the chemistry of sea water to be more like it was in the pre-industrial days, developed films that float on the surface to reduce the harsh sunlight hitting the coral, or even suggested using giant fans to circulate cooler water around the reef.
The new plan, from UQ and the consultancy BMT, might be a bit more practical. In nature, dead and damaged coral accumulates on the bottom of the sea, where it begins binding together and forming a foundation for new coral to take hold. The team wants to speed up that process by collecting dead coral and building new structures out of it, to protect the remaining reef and help new coral grow.
These structures often take the form of large pillars of coral called bombora – also known, in classic Australian fashion, as bommies.
"The idea is to take broken coral from the sea bed, wrap it into a natural-fiber net to provide a stable base for new coral recruitment, and place these artificial bommies in such a way as to protect other areas of the reef from cyclone wave damage," says Tom Baldock, a UQ professor on the project. "On a healthy reef, the wave energy is reduced by the coral structure, enabling broken coral to naturally bind to form a stable layer, initially through the growth of crustose coralline algae, or CCA.
"CCA helps bind coral rubble together to create the framework for reefs and releases chemicals which attract free-swimming coral larvae. Stabilizing and compressing the broken rubble into a single stable mound should assist this process."
These artificial bommies would each measure 2 m (6.6 ft) in diameter, and would be placed strategically to help speed up the natural repair processes and provide habitats for fish.
The team has so far received funding from the Australian and Queensland governments to conduct a pilot test.
Source: University of Queensland