In my fantasy world there are merpeople who have a magical ability to manipulate coral, they can make corals grow at a much faster rate than it naturally would, as well as control the shape it grows. The merpeople use this ability to grow material for pottery, jewelry and various tools, so instead of having to wait decades for corals to grow big enough and reach the hardness required for sculpting they only have to wait a few months at the very most.

I would want to know if there could be any dire ecological consequences that would arise from merfolk manipulating corals to grow much faster than they would normally and if there can be ways to prevent them.

  • $\begingroup$ Um...you should add the tags magic and science-based here, first of all. Second, ecological consequences? There's a reason magically sped plant or animal growth is handwaved, it's highly unrealistic thanks to the energy and nutrients required for said growth. I would suggest using magic or science alone here. $\endgroup$
    – Alendyias
    Sep 7, 2021 at 21:45

2 Answers 2


How magical is your world?

It's hard to give a solid answer without knowing how the magic works so I'll keep this general.

It's not entirely clear if you want individual coral polyps to be extremely large so a single skeleton can be used for some purpose or if you want to radically increase the generational cycle of a colony of coral polyps, so you get lots of raw reef material to work into some other form.

Either way, you're going to wreak havoc.

Giant coral polyps would involve creating new species and/or changing existing ones. We don't have any track record of deliberate speciation so the closest analog I can think of is species introduction (i.e., "invasive species"). Generally, introducing a species to a new environment where it has never existed before is a bad idea. Other species are almost certainly going to be lost in the process, possibly many other species.

Even if you limit yourself to "just" speeding up the life cycle of existing species, you run into problems.

A normal coral polyp has a lifespan of a couple of years. Based on your description you want "decades" of growth in "a few months". Since that's not exactly precise, I'll assume you want 50 years of growth in 3 months which works to a nice 200x increase. So, where is all the food and other resources for all of that coming from? Assuming you're not handwaving it all with magic (and given that you're even asking, I'm assuming that was not your plan), then you need to take those resources from the regional environment and, again, things die on a massive scale.

Once each of those polyps has done its thing, it dies. That means a lot more food for decomposers. On the scale you're describing, most ecosystems cannot handle it. Again, if you're not handwaving it all away, you're throwing the environment into chaos and things die (making everything worse).


Any time you increase the biomass of a single part of an ecosystem at a rate significantly higher than normal you will almost certainly have an ecological disaster.


If you're doing all of this with magic, then you can magic in the resources and magic away the waste. You can magically prevent species and habitat loss. You can do whatever you need. If you're going to use magic, embrace it. Or not, maybe you want to explore the consequences of this magic. Then just accept that your merpeople are going to destroy the environment and their descendants will not speak kindly of them. Assuming they’re not among the casualties.

Edited to add the following

Addendum: scale matters

There's a huge difference in impact between any random merdude can casually make Australia's Great Barrier Reef grow at 200x vs a small number of highly trained/talented/gifted mermages can, with effort, increase the growth rate of coral over 10 square meters. If you limit your scale, you limit the damage.

  • $\begingroup$ I wanted to see if i would need to handwave it with magic or not. To handwave the "food needed for rapid growth," can I solve it by making magic the energy source the corals use to grow? The decomposers i'm not sure. $\endgroup$ Sep 8, 2021 at 6:29
  • $\begingroup$ Your coral polyps will need organic chemicals to grow and reproduce and they'll need calcium and other minerals to build their skeletons (the reef material you're looking for). And oxygen to breath. So, you'll need magic to supply more than just "energy". If you're willing to cover all of that with magic, then why not add a little almost-true science and say you need to magic away all of the waste to reduce the harm caused to the universe by violating the conservation of mass? It doesn't actually balance out but it sounds true enough for a handwave. $\endgroup$
    – legio1
    Sep 8, 2021 at 14:25
  • $\begingroup$ OK. I know there is plenty of calcium in the ocean, so would it be possible to draw the organic chemicals and calcium needed from the environment through magic? $\endgroup$ Sep 8, 2021 at 17:23
  • $\begingroup$ There's plenty of everything you need in the ocean for the life that's already there. You can lean on that to an extent, but at some point, important resources are lacking and the ecosystem collapses. It really is a matter of scale. The more you use this magic, the more damage you do. $\endgroup$
    – legio1
    Sep 8, 2021 at 19:27

Coral Reefs are incredibly important ecosystems. They cover less than 1 percent of oceans but they actually support over 25 percent of all marine life. We don’t need merpeople to grow coral faster. There is a startup called Coral Vita which is accelerating coral growth rates by up to 50 times compared to how fast they grow in nature by using a process called micro-fragmenting. These are land based coral farms and Coral is grown in a controlled environment.


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