By Michela Reinink
After the devastating wildfires in Australia, the Great Barrier Reef is potentially heading towards the third mass bleaching of coral in five years.
Coral bleaching is caused by ocean temperatures. It is now a “critical time” period, according to scientists, as the weather conditions over the next month will determine the final outcome.
The Great Barrier Reef, roughly the size of Japan, is the largest living structure on Earth. The reef, who’s condition status was downgraded from “poor” to “very poor” in 2019 by the Great Barrier Reef Marine Park Authority, may be able to recover if weather conditions cool down in the coming weeks. If not, the extensive damage could be of similar severity to the bleaching events of 2016 and 2017. The 2016 event resulted in the death of 30% of the reef’s coral, while the 2017 event resulted in the death of another 22%. A report updated every five years on coral health determined that climate change was the biggest threat to coral reef, due to ocean temperatures climbing more often over the bleaching threshold. These bleaching events are a stark reminder of the challenges that will surely face in the coming decades.
The consequences of bleaching of the Great Barrier Reef are extensive. Economically, the Great Barrier Reef is a major driver of the local economy, bringing Australia $56 billion dollars for tourism, with 64,000 jobs tied to the reef. Total loss of all reefs would cost an estimated $1 trillion dollars.
There are also many biological implications of coral reefs; they host a multitude of species, increasing biodiversity of the shores, and also act as coastal protections from cyclones and storms. Threats to coral reefs are also threats to the survival of many species. In what is being called the Anthropocene extinction (also called the Holocene extinction), a present-day mass extinction event of species due to human activity, biodiversity conservation is of the utmost importance.
Ecologists and conservationists continue to search for innovative solutions. Surviving coral found in some coral graveyards has been dubbed “super coral”, and this super coral may have great potential for use in coral reef recovery methods. The idea is that the super coral is of superior genetic quality and contains higher survival capabilities. In theory, this super coral will eventually become more and more common as it is naturally selected. So scientists believe that manually accelerating the natural process of evolution by breeding super coral, and replanting it on the reefs, could be the key to increasing coral resilience and minimizing further coral reef death.
However, as with any ecosystem, coral reef ecosystems are intricate and complex. Any habitat engineering ought to be done with great care, and only when backed up by thorough research. One major concern that is often overlooked is that coral superior in tolerating heat may only be able to do so at the expense of other traits. Super coral that is well-adapted to current environmental stressors may be genetically lacking in qualities that would be able to resist other stressors (change in ocean pH, for example).
So manipulating the environment such that there is an overrepresentation of a certain type of super coral may provide a quick-fix now, but could present problems in the future. Some corals will be able to tolerate several stressors, but the super coral selected to be bred must be carefully assessed for such capabilities before any action is taken. If it is not, there may be disastrous outcomes for coral genetic diversity and survival capabilities.