Extinction or Survival?
- ninoxmitwpu
- Nov 25, 2021
- 4 min read
The Great Barrier Reef is one of the seven wonders of the natural world. Larger than the Great Wall of China, it is Australia’s one of the most remarkable natural gifts. the Great Barrier Reef is blessed with the breath-taking beauty of the world’s largest coral reef. The reef contains an abundance of marine life and comprises over 3000 individual reef systems and coral cays and hundreds of picturesque tropical islands with some of the world’s most beautiful sun-soaked, golden beaches. Because of its natural beauty, the Great Barrier Reef has become one of the world’s most sought-after tourist destinations. A visitor to the Great Barrier Reef can enjoy many experiences including snorkeling, scuba diving, aircraft or helicopter tours, bare boats (self-sail), glass-bottomed boat viewing, semi-submersibles, and educational trips, cruise ship tours, whale watching, and swimming with dolphins. Located in the Pacific Ocean, The Great Barrier Reef extends in roughly a northwest-southeast direction for more than 1,250 miles (2,000 km), at an offshore distance ranging from 10 to 100 miles (16 to 160 km), and its width ranges from 37 to 155 miles (60 to 250 km). The Great Barrier Reef has an area of some 135,000 square miles (350,000 square km), and it has been characterized, somewhat inaccurately, as the largest structure ever built by living creatures.
While it’s known mostly for its large maze of colorful reefs, its intricate architecture also provides a home for a huge number of animals and plants. Some of these, such as turtles and crocodiles, have been around since prehistoric times and have changed little over the millennia. The breathtaking array of marine creatures includes 600 types of soft and hard corals, more than 100 species of jellyfish, 3000 varieties of mollusks, 500 species of worms, 1625 types of fish, 133 varieties of sharks, and rays, and more than 30 species of whales and dolphins. Coral reefs only comprise about seven percent of the Marine Park and the World Heritage Area. The rest of the Marine Park is an extraordinary variety of marine habitats, ranging from shallow inshore areas — such as seagrass, mangroves, sand, algal and sponge gardens, and inter-reefal communities — to deep oceanic areas more than 250km offshore. Rather than having one level of protection throughout the Marine Park, the area is instead divided into different zones. Each zone has different rules outlining permitted activities and those that are prohibited.
In the past 20 years, climate change has emerged as the single biggest threat to the future of the GBR and reefs worldwide. The evidence is unequivocal. Corals are highly susceptible to small changes in water temperature. Warming of as little as 1C maintained for eight weeks is enough to cause coral bleaching — which can lead to death. Mass bleaching, unheard of before the 1990s, is now becoming a regular occurrence, with major events in 1998, 2002, 2010, 2016, 2017, and 2020. We now know coral reefs take about a decade to recover after serious damage. Mounting evidence suggests that as reefs recover, they are changing in composition and diversity. And as marine heatwaves become more frequent, there is less and less time for recovery. It’s a vicious spiral.
And, despite another widespread bleaching event in 2020, the Australian Institute of Marine science monitoring report for 2021 shows that from north to south, corals are starting to recover. This welcome news reflects the relatively benign conditions the reef experienced last summer. But even though the GBR is unquestionably the best-managed reef system in the world — thanks to significant government investment over the years, and the substantial efforts of farmers, tourism operators, regulators, and the public — the longer-term picture is not so positive. 40 years of data clearly show the largest and most diverse reef system in the world is under growing pressure from the combined effects of coral bleaching, outbreaks of coral-eating crown-of-thorns starfish, cyclones, and poor water quality.
Today, there are still many parts of the reef that remain in excellent condition — the ecosystem has huge in-built resilience that allows coral to recover when given the chance — but the number of such reefs has been declining over time. And the number of reefs in poor condition is increasing.
In 2021, widespread recovery was underway, largely due to increases in fast-growing Acropora corals. Survey reefs experienced low levels of acute stressors over the past 12 months with no prolonged high temperatures or major cyclones. The number of outbreaks of crown-of-thorns starfish on survey reefs has generally decreased; however, there remain ongoing outbreaks on some reefs in the Southern GBR. In 2020, most of the surveyed reefs experienced heat stress accumulation that produced widespread coral bleaching but was below thresholds where widespread mortality is expected to occur. Consistent with this, surveys in 2021 recorded low coral mortality from the 2020 bleaching event. The Great Barrier Reef remains exposed to the predicted consequences of Climate Change including more severe cyclones and more frequent and intense marine heatwaves. The observed recovery has been seen previously and can be reversed in a short amount of time.
Despite this year’s good news, the trend is clear, and the next major bleaching event is only ever a summer away. All the planet’s coral reefs face the same threat. If global emissions are not brought under control, and quickly, the vast majority of reefs around the world will disappear by mid-century, and those that remain will look very different to those we enjoy today. Reducing emissions alone will no longer be enough. There is already so much warming locked into the global system we also need to do everything we can to bolster reef resilience now.
It’s a huge effort that will take a decade or more. But we won’t know what we can accomplish unless we do the research. And, while it’s tempting to reduce such a complex issue to simple statements such as “the reef is fine” or “the reef is dead”, the truth is that while the trend is worrying, there remains much to be hopeful about. In the end, it is up to all of us. If we want to save the world’s reefs, we can, by working together. The place to start, as with most things, is with a firm basis.
Co-Authors —
References —
https://www.gbrmpa.gov.au/the-reef/reef-facts
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