Planted reef reproduction seen for first time at Moore Reef
In a breakthrough moment for reef recovery spawning of new coral planted by hand off the coast of Cairns has been documented on video for the first time in Australia.
In a breakthrough moment for reef recovery spawning of new coral planted by hand off the coast of Cairns has been documented on video for the first time in Australia.
The spawning event at the Moore Reef on Sunday night was witnessed by marine biologists, videographers, and PhD students from UTS Sydney and was part of a reef-wide synchronised reproduction cycle that usually follows the full moon in November.
There was a buzz of excitement on-board the Reef Magic pontoon in the lead-up to the event as excited scientists got ready for a camp out 30kms off the Cairns coast.
In a mirroring of the activity in the water there was dancing in celebration of the reproduction event during a night dive briefing.
Then it was time to suit up and slip beneath the surface.
Two teams of divers and snorkellers got in the water about 8.30pm on Sunday, one group swam into the coral lagoon directly in front of the pontoon while the other went to site of a reef restoration project to the east of the platform.
Since 2020 an arm of the confectionery giant Mars Incorporated have been anchoring “stars” made of rebar to the ocean floor to which coral fragments have been attached with zip ties.
Mars Sustainable Solutions marine program manager Freda Nicholson for years has been monitoring the growth of the coral and described seeing polyps spawning as a full circle moment.
“You can see the evidence of this happening (in pervious years) but that’s the first time we’ve actually been in the water while it’s happening and (we’ve) been able to physically see it and film with a GoPro, so that was really cool,” she said.
“It’s been really nice to see it from the start, it’s like a proud mum moment, the corals are my kids.”
While the planted coral spawned on cue as expected at the Mars reef stars site, Ms Nicholson said there was no known explanation as to why neighbouring corals didn’t spawn at the same time.
“No one knows exactly why different species spawn on different nights or even different corals on different parts of the reef spawn on different nights,” she said.
“And for some reason, that particular site has always behaved slightly differently to other corals on this reef.”
Coral spawning on the Great Barrier Reef is a spectacular annual event involving thousands of corals simultaneously releasing eggs and sperm into the water to create a scene described as being like an “underwater snowstorm.”
Soon after spawning, coral larvae, known at this stage as prawn crisps, float to the surface and if conditions are right embryos settle on a hard surface such as old coral skeletons after developing hairlike structures that give them ability to swim.
However, PhD student Hannah Kish from the Sydney University of Technology said there was knowledge gaps surrounding exactly how coral embryos find a host rock.
“We’re assessing the sensing ability of larvae to see if they smell out good locations or if it’s more happenstance,” she said.
Ms Kish said researchers at Moore Reef, under UTS coral expert Dr Jen Matthews,
have been experimenting with nutritional dosing of corals with essential sterols to determine if the survival rate of offspring can be improved.
“So we’ll place settlement tiles into our different bowls that have different treatments … and we’ll see how their settlement rate is, then we’ll track how well the corals on the settlement plate survive to the next stage,” she said.
Also on the Reef Magic pontoon overseeing the spawning event was Great Barrier Reef fish behaviour and coral research expert Dr Eric Fisher.
The head of GBR Biology said leading up to spawning tourism workers who relied on the reef for a living and scientists shared information from different sites in a collaboration to better understand the reef seeding process.
“The beautiful part of it is you’re (part of) this whole network of people that rely or work or live on the reef starting to be united by this one event,” he said.
“Its that deep love affair that connects people to the reef.
“So that’s pretty special.”
The spawning event was particularly significant this year following a loss of up to 20 per cent of reef flat coral cover off the coast of Cairns caused by heat stress and the impacts of Cyclone Jasper in 2023, Dr Fisher said.
With warming sea temperatures being identified by scientists and reef-management authorities as the greatest threat to the reef, stakeholders have been apprehensive following an evolving Australian emissions policy.
The federal government announced in September a new national target to reduce greenhouse gas emissions by 62-70 per cent on 2005 levels by 2035, but this week the Liberal Party formally abandoned a goal of reaching net zero by 2050.
Referencing increased frequency and intensity of marine heatwaves and mass coral-bleaching events Dr Fisher was asked how he imagined the reef in one hundred years’ time.
“I’m optimistic, and I’m incredibly worried,” he said.
“I’ve seen modelling where this reef (Moore Reef) disappears … and that’s a really sobering thought.”
The master reef guide said safeguarding the future of the reef needed a holistic approach that included boosting resilience while at the same time advocating for global emission reductions.
“What can we do now? he asked.
“We need both, we can’t alienate them and that’s always the hardest story to tell.
“I’ve been trying to tell that story for seven years now, and I love now the fact people are seeing climate change, there’s an acceptance we are in a climate crisis.
“And people know that and want to make changes.”
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Originally published as Planted reef reproduction seen for first time at Moore Reef
