The spectacular coral spawning event that occurs off Western Australia’s Ningaloo coastline each year has been successfully simulated for the first time under controlled conditions at the Minderoo Exmouth Research Lab.
During spawning, the corals release a shower of tiny gametes into the water column to cross fertilise. The resultant larvae drift with the currents before settling back onto the reef, carrying with them the hope for growing new coral colonies that form the building blocks for coral reef ecosystems.
The coral larvae now growing in Exmouth are being used by scientists from the Australian Institute of Marine Science and The University of Western Australia to examine why some individual corals are more resilient to heat stress.
Minderoo Foundation Flourishing Oceans Initiative Director Dr Tony Worby explained, having the Lab built on the doorstep of the World Heritage Ningaloo Marine Park has given researchers unprecedented access to high tech facilities that could ultimately help to protect parts of the reef from coral bleaching.
“We know the prediction is that the water at Ningaloo will reach temperatures warm enough to cause coral bleaching each year by 2049,” Dr Worby said.
“Corals will only spawn in a laboratory when the conditions perfectly replicate nature, so we’re really excited to see the success in spawning Ningaloo corals for the first time and it’s a testament to the quality of the facilities that have been built by Minderoo, in collaboration with AIMS that this has been achieved within six months of opening. We’re pleased that we’ve been able to move rapidly towards trying to find some solutions.”
Once fertilised, the tiny pink larvae are left to grow out in big culture tanks for a few days until they are robust enough to transfer to the temperature-controlled room, where the AIMS/UWA researchers will expose the corals to heat stress experiments in replicate tanks. After several days, those corals that have proven resilient to heat stress undergo whole genome DNA sequencing to explore the genetic variants that confer this tolerance.
Lead Researcher from AIMS and the UWA Oceans Institute Dr Luke Thomas said larvae are an elegant and simplified system to explore the drivers of heat tolerance.
“The Lab is based on technology from AIMS National Sea Simulator in Townsville,” Dr Thomas said. “It gives us the ability to manipulate the water temperature affecting Ningaloo corals and their larvae with unprecedented precision. It’s really expanded our capacity to address a range of new questions about coral biology. It also allows us to generate reliable, reproducible data that is a fundamental component of science.”
AIMS@UWA PhD candidate Shannon Duffy is working on understanding the genetic drivers and spatial patterns of this natural variation in coral thermal tolerance at Ningaloo.
“The ultimate goal is to help inform local management and conservation efforts,” Shannon said. “We’re focused on understanding how much natural variation in bleaching-resistance exists at Ningaloo, and how genetic tools can be used to identify and harness that variation to safeguard the reefs.”
This year’s spawning event has the team at the Exmouth Research Lab working alongside a pioneer of worldwide studies into coral spawning, AIMS Dr Andrew Heyward.
“This is an important milestone in research at the Ningaloo Marine Park,” Dr Heyward said. “If we can determine the genetic variants that confer heat resilience in coral larvae, then we can develop DNA probes to scan the adult populations in the wild. If we can find important genes that are associated with naturally heat tolerant corals, we can focus on protecting those corals or target our restoration efforts using these individuals.”