The temporal and spatial scale of coral bleaching: chasing corals
By Ana Vila Concejo, Associate Professor in the Faculty of Science, The University of Sydney
The documentary Chasing Coral provides undeniable visual evidence that coral reefs around the world are vanishing at an unprecedented rate in coral bleaching events caused by climate change.
Chasing Coral highlights the 2016 bleaching event in the northern Great Barrier Reef; this is important because it describes how coral bleaching is evident in the temporal and spatial scales, which are typically hidden from the public view. The spatial extent of the bleaching covered thousands of kilometres and expanded all over the world; the temporal scale saw coral turning white on a matter of days. This begs the question: what would we think if most of the trees in the world suddenly turned white in a given year? People would be alarmed and there would be no way to deny it; this documentary shows how this has happened to the world’s coral reefs and argues that the alarm raised has not been nearly enough for us humans to consider changing the way we live.
The effects of climate change on the Great Barrier Reef has been a component of the research to come from the University of Sydney’s Geocoastal Research Group and One Tree Island Research Station, which have mostly focused on the geology and geomorphology of coral reefs at different time scales with special emphasis on the geologic resilience of the Great Barrrier Reef, and the effects that sea level change have on the morphology, hydrodynamics, and sedimentation of coral reefs; the effects of coral bleaching are also a part of their research. .
The Geocoastal Research Group’s studies in coral reefs have shown that the Great Barrier Reef has been a resilient feature over hundreds of thousands of years. As sea levels rose and fell over the last half a million years or so, the Australian continent has seen about eight Great Barrier Reefs grow and die. Indeed, there are Dreamtime stories where the first inhabitants of Australia tell their account of changing sea levels and how the reef changed. We know that, from a geological point of view, the Great Barrier Reef is resilient. Yet, we have established that small changes in sea level might trigger large changes in the growth and morphology of coral reefs. We know that coral reefs are the greatest wave dissipaters in the world and that, without them, the coasts that they protect would be exposed to waves larger than the waves they receive now. We are also starting to understand how wave exposure determines the geologic evolution of reefs.
The past few decades have seen unprecedented climate change and scientists have proven over and over that this climate change is due to human causes. Consequently, coral bleaching has been happening somewhere almost every year, and in three occasions (1998, 2002, and 2016-17) this bleaching has occurred on a global scale, causing the dead of large proportions of the coral around the world. If we just focus just on the Great Barrier Reef, just the 2016 event was so severe that caused the dead of 2/3 of the coral in the upper third of the Great Barrier Reef, Professor Terry Hughes, in an event organised by the SEI, told us about their scientific findings and what needs to change if we want the Great Barrier Reef to revive for generations to come. Only recently, in the SMH, Professor Emma Johnston wrote about the efforts that scientists are doing to preserve the coral reef that includes creating heat resisting algae symbionts that can be frozen and released to the reef during bleaching events. However, we all know, or should know that the first step to help the reef is to change how we obtain our energy and switch to renewable energy.
Further discussion on Chasing Coral, the need for climate action and the research from the Geocoastal Research Group will be explored on October 16 2017, at Coral Bleaching in the Great Barrier Reef with a screening of ‘Chasing Coral’. This SEI film screening in collaboration with the Geocoastal Research Group and Sydney Ideas will be followed by a panel discussion featuring Assoc Prof. Ana Vila Concejo (chair), Prof. Iain McCalman, Prof. Maria Byrne, Assoc Prof. Jody Webster, and David Ritter.
Ana Vila Concejo: My career started in Spain, where I did my undergraduate and MSc studying urban beaches at the University of Vigo; and Portugal, where I completed my PhD at the University of Algarve investigating the short and medium term evolution of tidal inlets in a barrier island system. Then I moved to Australia and started looking into the morphodynamics of flood-tide deltas in wave-dominated coasts within the framework of an ARC funded linkage project which was based in Port Stephens. In 2010 I started researching the morphodynamics of coral reefs, particularly the processes that transport and accumulate sand in backreef environments and the role that reefs have as wave dissipaters. In 2011 I was awarded an ARC Future Fellowship to support my coral reefs morphodynamics research and to continue the studies in the dynamics of coral sands. I am the Deputy Director of One Tree Island Research Station; between 2012 and 2015 I was the Director.
Header image: by Sabangvideo via Shutterstock, Stock photo ID: 669591700.