- Acropora reproduction in our hobby
is almost always done by just cutting fragments.
We don't breed corals in our reef tanks
and in some aspects, the fragments that you might buy
could be thought of as the same colony it was collected
many years ago and then just passed down through vendors
and hobbyists by breaking off frags and growing them,
so if we're not gonna breed corals
and if we're looking to grow corals
as fast as we possibly can,
how exactly should we cut them from the colony?
Does it really matter?
Hi guys and girls, I'm ReefMan
and this week we'll be talking
about the impact of fragment size,
where exactly it's cut from the coral,
the orientation that you mount it in
and the presence of any tissue injury
on the overall growth and branching
of acropora coral fragments.
To do so, we'll be referring to a paper
published all the way back in 2003 titled,
"Coral Transplantation: Regeneration and Growth
"of Acropora Fragments in a Nursery",
so let's dive in!
So the first topic, fragment origin,
where it's cut from the mother colony could have an impact.
Would frags that are cut from the tips of branches
maybe grow better than those
that are cut from the base of branches?
Well, first off nearly all new branches
grew from the cut ends of the frags.
Almost no new branches grew from the center of the frag
and you can see this in your own frags,
it's really rare for a branch to split off
right from the middle of a frag.
Frags that are cut from below the last branching point
grew more branches than those cut from above that point.
However, this didn't last very long.
Over about four months or so it all evened out
and didn't really matter
from the perspective of new branches.
The frags that were cut from the bases of the branches
did grow more skeleton, though,
so they grew faster and perhaps they started out
a little bit thicker to begin with
because, as you know, branches get thinner as they go up,
so when your cutting your own frags,
if you want the fastest growth,
cut them from the base of the colony below the first,
or the last, actually, branching point if you can.
That's hard to do for obvious reasons.
Second topic, fragment length.
Longer is generally better!
Almost all four and seven centimeter frags
grew new branches within four months.
A little less than half of the teams one centimeter frags
grew new branches in the same period,
so longer frags, they're gonna grow more branches.
They grew more skeleton than the shorter ones,
so it's pretty clear, if you can,
make sure that when you cut your frags,
you cut them at least four centimeters long.
The team also looked at combining two three centimeter frags
together on the same growth platform.
These outperformed the single frags in growth,
so while you are reducing the number of frags
you have by half because you're mounting them together,
these double frag mountings will grow faster
than they would if you just mounted them alone.
Fragment orientation, does it matter?
Well, as you might expect,
corals do tent to grow up towards the light.
The results back this up and more branches and growth
are going in the upward direction
towards the surface of the ocean.
The actual direction that the frag is mounted in
compared to the direction it was originally growing
didn't really matter much, upside down or upright
to horizontally, but the growth was always upright,
so orientation really doesn't matter that much
when you're mounting frags,
just whatever looks best for you.
Tissue injuries are an interesting topic.
To test if an injured coral might grow slower or not,
the team used a water jet to clear tissue
from a one centimeter band, right in the middle of the frag.
Within two months, all the frags had healed
and covered this in new tissue
and those frags actually grew new branches
from the damaged section as well
and so, if you do have a few months for your frags to grow,
you could use something like compressed air, water,
a toothbrush, to remove a band of tissue
from the center of the frag
and something about the healing process
encourages new axial polyps to grow
and obviously those will then form new branches,
so in summary, a frag taken from the base of the colony
is going to grow faster
than one taken from the tip of a branch.
Your frags should be at least four or so centimeters long,
unless you wanna double them up where shorter lengths
might actually grow even faster.
The orientation that you mount your frags in
does not matter at all, do what you like
but if you want to encourage branching quickly
to get a mini colony going, you could use a toothbrush
or something to damage the tissue
in the middle of your frags in the branch
to increase the chance of new branches forming there.
The team does note that the main reason for not preferring
the small one or two centimeter frags
is just because of algae growing over them.
If you can control that in your system
better than they can control it in the ocean
than those very small frags could be viable
although they are gonna grow more slowly.
Small frags like that also hardly branched at all,
so you won't have a nice little colony quickly
with such a small frag.
I hope you enjoyed the video and learned something new
about acropora corals and how they grow in our reef tanks
after we frag them.
All of these tips are pretty cool, I thought,
but of course, we're not gonna be able
to only use the base of the branch for fragging.
To get the base, you're also gonna end up with some frags
from further up the branch,
so don't worry about it too much.
There is a link to the paper down below.
As always, it has a lot more information in it
than what I was able to cover here in this video.
Please do check it out, it's a good read.
Have a great day, please subscribe if you like the video.
I will see you next time, until then, be kind to each other,
have a fantastic day, bye!