Spawning School

Spawning School is a practical learning program in using coral larvae for reef restoration. Reef Recruits co-leads Spawning School with JCU TropWATER at the James Cook University Nguma-bada campus in northern Cairns.

Spawning School is offered to First Nations Land & Sea Rangers from the Cairns-Port Douglas area. Over the last three years, we have had the privilege of training more than 40 Rangers.

More information here.

2023
2024
2025

Spawning School takes place mostly on land so it’s easy to participate. Our coral parents are typically Acropora kenti collected from Pixie Reef, with permission from Yirrganydji Sea Country Elders. We collect them with Caleb from GBR Aquatics.

Coral spawning

We collect our corals on the day of the November full moon, then spawning follows a few days later. Spawning nights are always a highlight of Spawning School!

Waiting for spawning – red light only!
Checking for setting
A setting coral – spawn bundles visible at the polyp mouths
Coral spawning!
Spawn bundles ready to collect
Collecting spawn bundles by carefully skimming them off the surface
Collecting spawn bundles
Collecting spawn bundles
Intact spawn bundles and individual eggs from dispersed bundles
Washing away excess sperm by moving the embryos into clean water three times.
Washing embryos
Washing embryos
Collecting washed embryos for monitoring in the lab
Checking fertilisation rates and counting embryo subsamples
Embryos clean and happy and ready for bed.

Larval development

Spawning School runs from spawning night until the coral larvae are ready to settle and metamorphose into coral polyps. There are many developmental changes in coral larvae during this 7 day period – the only time in their lifecycle when they are on the move.

Caring for corals and larvae

Keeping corals and coral larvae alive and healthy takes time and care every day.

Collecting larvae to view under the scopes
Larvae spread out in Borogov trays for easy observation and counting
Monitoring larval health under the scopes
Checking water temperature in a larval culture
Checking water temperature in the parent coral tank
Water change in a small larval culture to keep larvae healthy
Using refractometers to test salinity
Monitoring salinity
Monitoring salinity

Learning and doing

Alongside caring for our corals and keeping our growing larvae happy, we learn about coral biology and how to care for them on the reef and in aquaria. This happens through a mix of classroom talks, lab practicals and hands-on activities used in coral reef management.

Using microscope cameras to examine coral skeletons
Coral ID discussions
Using the Coral Finder for coral ID
Practicing how to check for ripe eggs on old coral skeletons
Checking that our collected corals still have ripe eggs
Ripe red eggs – spawning is imminent!
Confirming our collected corals still have ripe eggs
Carefully break off a central branch and look for ripe eggs
Classroom discussions about coral biology
How the outdoor aquarium system works
How the indoor aquarium system works
Lots of activities to develop microscope skills

Hands-on science

Every year Spawning School includes an experiment conceived and designed with the Rangers to explore coral settlement. In 2023 we looked at whether settlement was affected by time of day, in 2024 we gave the larvae different materials to settle on and in 2025 we investigated the effect of temperature on settlement.

Counting larvae for each experimental unit (2023)
Placing settlement cages into main tank (2023)
Settlement underway in mesh-sided cages (2023)
Prepping settlement choice experiment (2024)
300 larvae in each container (2024)
Monitoring settlement on the devices after 24 hours (2024)
Settlement in temperature controlled conditions (2025)
Settlement in ambient temperature (2024)
Monitoring settlement after 24 hours (2025)

Community Days

Another highlight of Spawning School every year is welcoming family and friends from the communities where some of our Rangers live. It’s a great opportunity for community members of all ages to see what the Rangers are working on and for the Rangers to share their knowledge.

Awesome to share and connect with community from Yarrabah!

Participating Ranger groups