It’s official, we are waving goodbye to our precious coral reefs and it’s happening faster than any of us had realised.
This week, the ARC Centre of Excellence for Coral Reef Studies released a worrying report that confirms a huge depletion of coral reef populations in The Great Barrier Reef. The study was lead by Dr Andy Dietzel from the ARC Centre, and he and his co-authors studied colony sizes of coral in The Great Barrier Reef between 1995 and 2017. The results are shocking. Co-author Terry Hughes of CoralCoE has reported that they, “found the number of small, medium and large corals on the Great Barrier Reef has declined by more than 50 percent since the 1990s.”
Hughes went on to explain that: “The decline occurred in both shallow and deeper water, and across virtually all species—but especially in branching and table-shaped corals. These were the worst affected by record-breaking temperatures that triggered mass bleaching in 2016 and 2017.”
The impact of this bleaching is not restricted to coral depletion. As the study points out, fish live within these coral reefs and depend on them to survive. As is always the case, environmental changes have a domino effect. It is also a sad fact that coral reefs cannot regenerate as quickly if there are fewer of them, because they need to breed and produce larvae.
At this stage, you might be asking yourself “what is coral bleaching?”. It’s all to do with what coral eat: algae, and lots of it. The algae cover the coral, as tomato sauce might cover a toddler at dinnertime. However, unlike tomato sauce, the algae become stressed due to certain changes in the environment, including increases in water temperature and pollution. When the algae become stressed, they move away from the coral, leaving the coral bleached and white. The coral loses its food source and becomes more vulnerable to disease, which is what we can now see has been happening at record levels.
The authors of this report are very clear on what it will take to slow the decline of coral populations: “There is no time to lose—we must sharply decrease greenhouse gas emissions ASAP.” A sobering reminder that coronavirus is far from the only huge threat our world is currently facing.