A trip to the Great Barrier Reef

In July last year, I took my two boys to the north of Queensland to spend a week at Cairns and Port Douglas, diving on the Great Barrier Reef and also doing trips inland to rainforest and the Daintree River. I had been to the Great Barrier Reef once before about 20 years ago, but much further south in the Whitsunday Islands.  Aware that global warming was already damaging the reef, I wanted to give my boys a chance to see it while there was still time.

From Cairns we made a first trip out to Michaelmas Cay and Hastings Reef. These reefs are about an hour’s trip in a fast boat. My older son did a day of scuba diving, while I and my younger son went snorkeling.  Following are some photos from these trips.

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Michaelmas Reef (above) is underwater at high tide, and just out of the water at low tide. It is on the outer reef and there was quite a strong wind making the water choppy. Additionally, there was a reasonably strong current, so snorkeling was quite strenuous.

After a day on the Atherton Tableland inland from Cairns we did another trip out to Upolo Cay.  Some of us came ashore (to a quite small sand island) on the glass bottom boat, others like my sons dived off the big boat and swam to the island. Surrounding it were some magnificent coral reefs.  We all snorkelled on this second trip, and got quite good at free diving.

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As we came to the end of our time on Upolo Cay, the tide was coming in and the sand island disappeared beneath the waves.

That evening we drove about 30 km north along the coast to Port Douglas. The next day we took a very fast speedboat to Low Islands. The Low Isles were named by Captain Cook when he sailed up the coast of Queensland in 1770. The lighthouse was built in the late 1800s. These islands have flat coral beds around them not far below the surface of the sea, and green turtles swim across the coral beds grazing on the seaweed.  We saw lots of turtles, and dived down and swam alongside some.

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After a day finding crocodiles on the Daintree River, we headed out to the outer reef again and visited Opal Reef, perhaps the highlight of our trip. Opal Reef is in deeper water and there are some quite spectacular coral cliffs and bommies (outcrops).

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Some of the giant clams had spectacular colouring. Some were more than 1 metre across.DSCN4884DSCN4880DSCN4907DSCN4874DSCN4953DSCN4962DSCN4968

Some coral bleaching is visible in some of the photos above. Coral bleaching is due to thermal stress when sea temperatures rise. Coral bleaching is not always fatal, but has been one of the main causes of coral death around the world in the last 20 years. One of the marine biologists on our boat told me that in past decades there was a major bleaching event around once a decade affecting about 10% of the reef, and the reef could cope and recover from this level of bleaching. In the last few years, the bleaching events have become more frequent and are affecting more than 30% of the reef at a time.

Additionally, the higher sea temperatures also affect the growth and reproduction of corals. In 2016, for the first time, the annual spawning of the coral did not occur in the northern reef.  If this becomes more common, it will dramatically decrease the reef’s chances of recovering from bleaching events.

In a recent study, researchers analyzed data about bleaching events at 100 reef locations around the world from 1980 to 2016. They found that the rate of bleaching has increased more than fourfold in the past four decades — from once every 25 to 30 years back in the 1980s, to once every six years by 2016. That’s because ocean waters are warming up, according to the study published in Science.

http://science.sciencemag.org/content/359/6371/80

Extensive aerial surveys and dives have revealed that 93 percent of the world’s largest reef, the Great Barrier Reef, has been damaged by coral bleaching. The culprit has been record-warm water driven by El Niño and climate change that has cooked the life out of corals.

Another study has estimated that the 2016 ocean heatwave killed 30% of the Great Barrier Reef. Combined with a 2017 temperature spike, half of the 2 billion corals on the reef have died since 2015.

https://www.smithsonianmag.com/smart-news/2016-ocean-heatwave-killed-30-percent-great-barrier-reef-180968844/#Vj2YUdGK4XxDiLLh.99

This trip to the Great Barrier Reef really brought home to us the reality of climate change and the massive impact it is already having.  I just hope the human race can act before its too late, though I am not optimistic.

 

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