How do we save the worlds oceans? Coral Conservation

I love diving and so do many other people. It is an amazing activity and there is nothing else like it. Coral reefs are hands down the coolest place to go diving. The amazing structures and beautiful colors of the corals, all the fish swimming through and around the reef creates this magical seascape that is nearly impossible to described. But a sad thing has been happening over the last few decades. These beautiful places are disappearing. Massive bleaching events have spread across the world and are occurring at an alarming rate. Bleaching is when the symbiotic zooxanthellae (photosynthetic organisms) are expelled from the corals. These microorganisms are how corals survive off of sunlight and losing them means almost certain death for corals.

Bleaching occurs when the corals are stressed out. Corals can be stressed because of high temperatures, acidic water conditions, pollution and more. The biggest concern and cause of bleaching is the rise in global sea temperatures. This rise in temperatures will cause more and more bleaching events to occur since the threshold is closer to the normal water temperature.

Loosing corals is not just a loss of a pretty place but the loss of the most diverse and biologically rich ecosystems in the world. Most marine species either live within, spawn at, or interact with reefs at some point in their lives. Reefs provide much needed shelter and food for many species. As these reefs disappear these species are losing their habitat and the ability to live. The likely hood of losing these species along with corals rises every year.

So how do we stop this? There are many ways that researchers and scientists are trying to recover the worlds corals. Corals are fascinating organisms. Corals are not one animal but a collection of hundreds of thousands of tiny coral polyps forming massive colonies that share resources. There are hard corals that form a rocky skeleton made of calcium carbonate, and soft corals have larger more flexible bodies that do not have the hard structure of stony corals.

                                        Hard coral                                                    Soft Coral

Hard corals can break, the skeletons are made of a fairly soft calcium carbonate, and it can be broken into pieces. A broken piece of coral is not dead it can actually form its own new colony. This practice is known as fragmentation planting. Scientists will go out and break small pieces off of a larger coral and plant them to grow on their own.

These fragments take a long time to grow, it takes years for them to double in size. Large corals in the ocean, the “boulder corals” can take around 500-1000 years to grow. It takes most corals around 100 years to grow large enough to be at a reproductive size. So, it is not the best solution, it takes too long. So, how do we speed it up?

This is where the relatively new and exciting concept of micro fragmentation comes in. Researchers discovered that when a piece of coral is cut off it goes into a sort of frantic growth mode where it tries to replace the lost mass and grows incredibly quickly. This means that by breaking corals into small pieces the growth rates can be increased. You may be thinking “well how does having a bunch of tiny corals help? Now they have to grow even more to get to size.” That is actually not the case. There is a fascinating effect where if you take two pieces taken from the same donor colony and put them close together, the two pieces rather than fighting for space actually fuse together into one colony.

If you allow enough pieces to fuse together you can create a coral large enough to be reproductively active in around 2 years. This would normally take around 100 years to accomplish.

Check out this video about micro fragmentation: https://www.youtube.com/watch?v=hRBpZGOQmNo

Corals can be restored in a number of ways but the most effective way I have seen is fragment planting especially utilizing micro fragmentation. But there are a lot of other things that have to happen before the corals are truly safe. Simply putting more corals out and growing more will not prevent the planted corals from dying along with the naturally growing corals. In order to save the corals, we have to reduce or eliminate the stressors that are killing them. This means large scale policy changes to limit and prevent the future escalation of climate change and stabilizing the climate. Even if we cannot stop the changes if the changes can be slowed the corals will have more time to adapt to the changes. This leads to the idea of assisted evolution.

Assisted evolution is probably the most hotly debated concepts of coral restoration. Assisted evolution can take the form of researchers artificially altering the gene pool of an area to resist a stressor. If the same species of coral lives in the Indian ocean and in the Caribbean, and the Indian ocean population is thriving and the Caribbean population is dying. Assisted evolution would be moving corals from the Indian ocean to the Caribbean and introducing the temperature resistant genes into the Caribbean population. The biggest issue with this is the possibility of unwanted passengers. Many organisms that can harm or kill corals are tiny and difficult to see. The last thing we want is to bring the coral equivalent of smallpox blankets into the already struggling coral reefs. There is a disease known as stony coral tissue loss disease that is often referenced in these debates since it is a particularly nasty disease that we do not want to spread anywhere else.

The large brain coral on the right is probably between 500-1000 years old and stony coral tissue loss disease has killed it in less than 1 year. For more information about assisted evolution check out this paper by Van Oppen, et al. https://www.pnas.org/content/pnas/112/8/2307.full.pdf

There are so many ways that we can help corals and try and prevent further damage, but it will take a lot of coordination and working together. So do your part and support the conservation of corals in whatever way you can. Whether it is in the fight against climate change or just supporting politicians that emphasize environmental protection. Anything we can do to stop or slow the degradation of the environment will help.