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  • Image credit: Troy Mayne, Oceanic Imagery

    Image credit: Troy Mayne, Oceanic Imagery

Journey to the far North Great Barrier Reef

Karen JohnsonCitizen scientist and former AMCS staff member Karen Johnson recently spent 10 days collecting data on the health of coral reefs for CoralWatch, a not-for-profit organisation monitoring coral health globally. This is a small excerpt from Karen’s journal and her firsthand experience of how the recent coral bleaching epidemic has affected reefs between the Torres Strait and Cairns.

A couple of weeks ago I was given a remarkable opportunity to spend 10 days on a live-aboard boat as a citizen scientist. We dived, monitored and explored remote coral reefs from the Torres Strait to Cairns, collecting data on the health of our corals for CoralWatch.

Shockingly, all the reefs we visited had evidence of bleaching. The outer reefs had a greater diversity of corals, fish and invertebrates.

Image by Chris Roelfsema Image by Chris Roelfsema

While there is no doubt that coral bleaching is a significant and serious threat to our corals, it is not true that the reefs are no longer worth diving. On the contrary, we found spectacular reefs which made for fantastic diving, well worth a visit.

The size of the Great Barrier Reef is mind blowing and requires all hands on deck (management, research, citizen science and community) to help conservation efforts.

The sites we visited surprised us in their morphology, diversity and colours and so worth maintaining the pressure to preserve.

18 April

As I step ashore to Thursday Island the breeze carries a warm greeting. How big Australia is, when you can fly to one of our outlying remote islands and feel you're in another country and culture. The size and remoteness of Australia shows the need for ‘citizen scientists’ to help monitor and care for this big country of ours.

Johnson Islet is a beautiful small vegetated island in the Torres Strait. As we crossed the shallow reef flat we saw startling fluorescing coloured corals glowing in the shallow water. The unnatural neon colours are evidence of the coral under stress; fluorescing is the stage before bleaching. We wandered the reef flat and were shocked to see vast soft corals colonies are a 'day-glo' yellow.

In disbelief, I scanned the reef flat and saw the broad scale extent of fluorescing corals and the loss of habitat.

A reef flat that should have been teaming with life was eerily devoid.

In the field we compared and recorded the colours of the coral against a CoralWatch colour chart. CoralWatch uses coral colour as an indicator of coral health to monitor bleaching. The data is then uploaded via an app to a global database and contributes to monitoring, reporting and management strategies.

Image by Trevor Barrenger Image by Chris Roelfsema

19 April

I could see evidence of coral bleaching from the boat as we arrived at Monsoon Reef.

The water was warm like a bath. As I approached the reef flat I was disheartened to see the full extent of coral bleaching from within the water.

Elderly porites corals were devoid of colour and reduced to bleached boulders, spectacular foliaceous plates appeared white and fragile. My random 20 samples taken for CoralWatch showed the hard corals were having a hard time.

I saw two beautiful whitetip reef sharks, a graceful old turtle as well as angel, butterfly, trigger and damselfish, but this was my first reef dive where I haven’t been able to find clownfish.

Image by Chris Roelfsema Image by Chris Roelfsema

As I jumped into ridiculously warm waters at Collette Reef (30 degrees), I circumnavigated coral islets to collect CoralWatch data.

My dive highlight was a friendly remora who wanted to be my pilot and the beautiful array of diverse fish life. Harder to take in was the high percentage of bleached corals. This was another struggling reef.

Image by Trevor Barrenger Image by Trevor Barrenger

20 April

There are nearly 3,000 individual reefs in the Great Barrier Reef and not all of them are named. Reef 11-090 is a stunning reef around 100 kilometres from mainland Australia. The water temperature here was still a warm 28 degrees, only slightly cooler than previous dives.

My beaming smile made it hard to keep the scuba regulator in my mouth.

This reef still had bleaching but comparatively it appeared to have a greater array of fish and healthier corals. I found vast communities of soft corals like undersea flowers; flashy coloured nudibranchs and chunky garden eels swam amongst an interesting geography of coral bommies.

The reef sharks were inquisitive and attentive buddies who accompanied me as I explored and collected CoralWatch data. This was such a remote location, I felt incredibly privileged to be where not too many others have the opportunity to visit.

Image by Chris Roelfsema Image by Chris Roelfsema

As we travel away from mainland Australia toward the reef edge at Turtle Farm, Great Detached Reef, I noted seeing less fluorescing corals and greater coral coverage within the reef communities. The temperature was 28 degrees and there was a diverse array of life to be explored among coral islets.

Great Detached Reef is the final frontier and lies beyond the Great Barrier Reef; a remote wilderness with infrequent visitors. Transported by the ocean’s current my dive buddies and I drifted along the outer edge of a breathtaking coral wall that dropped off to unfathomable depths - a great blue void. A greeting party of big whitetip reef sharks checked us out.

We travelled past noticeably different coral colonies - solid bolder corals, plate corals, flowering soft corals, gorgonians fans, sea whips and branching staghorn corals - which reflect of the different environmental and physical conditions these corals are exposed to.

As we continued further from the mainland, I saw less bleached and fluorescing corals as well as the biggest crown-of-thorn starfish and a variety of pelagic fish.

Image by Trevor Barrenger Image by Chris Roelfsema

Wood (Woodie Point) has spectacular geography. My dive buddy and I swam to the coral peninsula, and descended to an amazing wall, with caves and hollows to explore. We found a stunning array of large, brightly-coloured red and yellow gorgonians. The dense latticework of the sea fans was home to clinging feather stars, worms and molluscs. At the tip of the peninsula lay a rusting coral covered old mooring line.

We navigated back along the other side of the peninsula wall marvelling at the soft, hard and blue corals and the pretty nudibranchs in the shallow coral gardens. The corals here for the most part looked healthier and are home to lots of little damsel, angel and butterfly fish. There were bleached and fluorescing corals among the community but these were not the majority.

At Mad Surgeons Reef, Great Detached Reef, I swam against the current, marvelling at schools of big pelagic fish, including surgeonfish, humphead wrasse and a couple of whitetip reef sharks.

I also found the biggest clam I have ever seen and a large but timid octopus that was a little camera shy.

Image by Chris Roelfsema Image by Chris Roelfsema

22 April

We dived at Inside Wall, Tijou Reef and were watched by silvertip reef sharks and an abundance of fish schools including damsel, parrot, unicorn, leatherjacket and triggerfish as well as wrasse.

In the shallows, coral islets served as anchorages for soft and hard corals rich in diversity with limited bleaching.

That night under the light of a full moon we returned to the water where I met two beautiful loggerhead turtles. The oldest and biggest I found asleep in her turtle grotto; her shell was easily 1.5 meters in length. It was total turtle love.

Image by Trevor Barrenger Image by Trevor Barrenger

23 April

Travelling to Sandbank No 7 we were met by a school of inquisitive grey reef sharks who accompanied us on our dive. I saw loads of big fish: schools of surgeon, sunset platy, trevally, banner, butterfly, damsel and anemone fish as well as humphead wrasse. Diverse corals made homes for abundant little fishes.

Sandbank No 7 is in a designated marine sanctuary and the underwater flora and fauna at this site were amazing.

Image by Trevor Barrenger Image by Trevor Barrenger

13-117b Reef came alive at night and there was a plethora of sea life to see. The bommies were tower blocks, their worn hollows and passageways night refuges for sleepy marine life.

I found stunning chunky garden eels patrolling the passageways and sleeping coral trout in tiny hollows. A large hermit crab had carried his trumpet shell into the bommie for the night. He became a little grumpy with the torch beam and picked up his shell and retreated further into the shadows.

Image by Trevor Barrenger