I first learned about the work SECORE International is doing while I was deep in a research rabbit hole trying to learn about how coral reproduce. I had read an article somewhere about problems associated with coral restoration through fragmentation alone and I wanted to understand why.
Fragmentation refers to the process of taking smaller pieces of coral that break off of large coral during storms, from human damage, or any number of other factors. These small pieces are then collected and carefully attached to large structures that keep the coral out of the sand, away from predation, and at the right level to receive enough sunlight. It also makes it easier for humans to monitor, clean and protect them until they grow big enough to be replanted out in the reef. The new coral that grows from the small fragment is a clone – genetically identical to the original coral it broke off of.
Problems with this process arise if the majority of the coral being raised in nurseries and out-planted are all from a few genetic strains. This would dramatically reduce the overall genetic diversity of coral populations – and loss of genetic diversity is associated with all kinds of other problems for almost every kind of organism. Not the least of which is severely limited opportunities for evolution to make it possible for coral to adapt to the conditions of climate change.
So, all this had me wondering, how do coral reproduce?
In my search to understand coral reproduction, I found an article titled Broadcast Spawners that goes into a very satisfying amount of detail about coral reproduction. Coral (and other broadcast spawners) have an annual event where they release their reproductive genetic material (egg and sperm bundles) called gametes. The bundles are released simultaneously and float to the surface where they mingle and the eggs become fertilized.
Once fertilized, the eggs immediately begin to divide and develop into embryos that will float around the ocean as plankton until they become larva. The coral larvae develop cilia (hair-like structures they can move in order to propel themselves through the water) allowing them to swim down to the ocean floor in search of a new home.
One of the major challenges for coral reproduction is that broadcast spawning requires a critical mass of egg and sperm for fertilization to take place. In locations where coral has been severely reduced, reproduction may simply not be possible anymore. So scientists have started collecting these gametes and doing a kind of in-vitro fertilization process. This can be done not only to increase overall fertilization rates, but also to promote certain genetic strains that have shown greater resilience to climate change conditions.
There’s another challenge at this stage – infrastructure. The aquaculture facilities required to raise the coral larva at a scale sufficient for meaningful coral restoration is substantial. This is an insurmountable barrier for many of the small communities where coral is found. This is where coral kindergartens come in!
Another amazing and wonderfully informative article by SECORE International – titled Engineering Restoration – outlines three key developments they have pioneered;
- Coral settlement substrates
- Coral Rearing In-Situ Basins (CRIB) aka coral kindergartens, and
- Coral germ cell collecting devices
Gametes are collected using their coral germ cell collecting devices, the coral larvae settle on the coral settlement substrate, and then they are sheltered and protected in floating basins called Coral Rearing In-Situ Basins (CRIB) aka coral kindergartens.
These developments not only make it possible to scale up restoration efforts, but also to do this in remote areas where it would otherwise not be possible.
Erica Lauer Vose 