This question is a modified version of my earlier question, where I will clarify some of my worldbuilding.

In my world, merpeople are capable of manipulating coral by making it grow at a faster rate than it would normally, as well as manipulate it to grow into a desired shape, as well as making it hardier and more resistant to parasites and wear. They use this ability for harvesting coral to make tools and jewelry. The process involves ensorcelling one coral (not the entire reef) so it grows faster than usual for a set amount of time. After it has reached the desired shape and size magic is used so that it starts growing at the normal rate.

I imagine that the coral grows from drawing upon magic as an extra energy source, and the magic makes nutrients and calcium more available for the corals.

I would want to know if its possible for the merfolk to use this ability responsibly, in a way that doesn't result in ecological disaster for the rest of the environment. Could that be achieved by only using it sparingly, and only making the coral grow only slightly faster than usual for a short period of time?

  • 1
    $\begingroup$ Do your merpeople have a means of collectively managing a reef? If so, you can probably use forestry or fisheries management as a model. Depending on the size of your community, it doesn't have to be very formal. A small village might get away with a collection of "gran-mer always said..." rules while a heterogeneous global industrial society will need committees or other bodies with formal power to set rules and military/police that can enforce those rules (a United Merpeople Reef Guard). $\endgroup$
    – legio1
    Sep 9, 2021 at 13:05
  • $\begingroup$ Exactly what problem(s) are your merpeople concerned with preventing? Using up natural resources or space? Encouraging pests by growing extra coral? (Does anything eat coral anyway?) Accidentally exposing animals or plants to magic? $\endgroup$
    – Cadence
    Sep 9, 2021 at 16:12
  • $\begingroup$ Using Up natural resources like calcium in the seawater and nutrients for other sealife $\endgroup$ Sep 9, 2021 at 16:42
  • $\begingroup$ @Cadence: plenty of things eat corals, crown of thorn sea stars are actually a pretty big problem. Ironically, though, those same sea stars are eating too much coral, so these mermaids might help achieve an actual balance and avert coral's extinction! $\endgroup$
    – Alendyias
    Sep 9, 2021 at 21:47

2 Answers 2



There are basically three variables:

  1. Amount of coral subject to accelerated growth
  2. Relative rate of acceleration (e.g., 10 x normal)
  3. Time span of accelerated growth

They can't all be maxed. But there should be a balance that meets the society's needs without destroying the ecosystem. For example, (assuming a merpeople society around a single, mid to large reef ecosystem), if you limit use of this magic to 1% of the total coral at any one time (and spread that out across the reef) you can probably have very high growth for a medium length of time. If you need to make a higher percentage of the reef grow fast, you can either reduce the rate or keep it "on" for only a brief amount of time.

Just a thought but if you required the mermage to manually feed and clean the accelerated coral you'd automatically limit the area they could accelerate.


Assuming your mer-men are D&D based, You could use a 'Merfolk only' coral based variant of 3rd lvl "Plant Growth" as coral grows as many would consider plants do.

"If you cast this spell over 8 hours, you enrich the land. All coral in a half-mile radius centered on a point within range become enriched for 1 year. The coral yield twice the normal amount when harvested."

Growth could be managed by methods to allow shaping through pruning, etc as the rate of growth is merely double natural growth.


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