New hope for coral reefs

Coral Reef

Scientists have found new hope for our damaged coral reefs in transplanting lab-grown coral larvae to the ocean. The venture has already seen a transplanted population of 100 healthy young corals thriving on Heron Island.

Coral can reproduce one of many different ways, depending on the type of coral. Coral can be male, female, or both! They can also reproduce inside or outside their bodies.

Most commonly, larvae are formed when eggs and sperm from the male and female are released into the water. Together, the eggs are fertilised by the sperm and form larvae that are attracted to the light at the water’s surface. The larvae will grow near the light, and eventually sink down to attach to rocks.

Larvae produced inside the body is a similar process; eggs inside the coral are fertilised by the water-borne sperm and mature inside the ‘mother’ until spat out to attach to a rock.

Sometimes, mass coral spawning can be observed. This is when all the coral of a particular species release their eggs and sperm all at once to increase chances of fertilisation. It occurs once a year, after a full moon when the tides are warm.

It was during the 2016 mass spawning event that Professor Harrison (Southern Cross University) and team funded by the Great Barrier Reef Foundation collected large amounts of sperm and eggs. The eggs and sperm were grown into over a million larvae before being transplanted back into the sea.

Eight months later, the 100 surviving young corals were discovered on Heron Island. “This is the first project of its kind on the Great Barrier Reef to successfully re-establish a population of juvenile corals from larvae settling directly on the reef,” says Professor Harrison.

coral reef

“The results are very promising and our work shows that adding higher densities of coral larvae leads to higher numbers of successful coral recruits.”

The reseeding project has been repeated for the 2017 mass spawning on Heron Island, and has already seen success results from the project. “I’m excited to announce that we’ve already observed successful settlement of the new coral larvae this year so it’s worked again.

“We’ll be monitoring the growth of the colonies and working to further refine the technique for potentially large scale application in the future,” said Professor Harrison.

While the research is an important breakthrough in discovering reparative measures for the reef, it’s not a band-aid solution. “In recent years, the impacts of climate change on the Great Barrier Reef have undoubtedly accelerated, as we saw with back-to-back years of bleaching.

“It is vital everyone keeps working to address climate change and build the Reef’s resilience, and for restoration strategies to be developed that can work over large areas.” says Great Barrier Reef Marine Park Authority Chief Scientist Dr David Wachenfeld.

Eliza Brockwell

Liked this article? Read Bragg Writing Prize runner up, Carol Ge’s essay on the decline of the Great Barrier Reef.

Eliza Brockwell

Author: Eliza Brockwell

Eliza is the Digital Producer for Careers with STEM. Eliza is passionate about creating content that encourages diversity of representation in STEM.

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