- Hi guy and girls.
I'm ReefMan and today I wanted to tell you about
a new paper that was just published on the 12th of March.
This paper is called Seabird Nutrients
Are Assimilated by Corals and Enhance Coral Growth Rates.
It's a pretty awesome title, right?
This paper is by a single author, Candida Savage,
and is about a study that began
in the islands of Fiji back in 2013.
The study wanted to look at the effects
of seabird populations
on the growth of coral just offshore.
Now, as reef-keepers, we have many options
in how we want to set up and run our tanks.
We can run an ultra low nutrient system
and strive for undetectable nitrates and zero phosphates.
We can run a dirty tank that has
a bunch of phosphate and nitrate.
We tend to see those maybe with soft corals a lot more
than stony corals like I have.
So there are a bunch of different ways we can do this.
And, of course, there's a bunch of tanks in between.
It's becoming more and more popular
to allow a small amount of nitrate
and phosphate in our tanks.
This study was made using two pristine
reef locations in Fiji,
an island called Namena with a seabird population
and another one called Cousteau, off the coastal resort
by the same name, which didn't have any birds present.
It's important to note that both locations
are away from human sources of pollution.
After all, the study wanted to establish
a potential link between seabird waste and coral growth,
so it wouldn't be good if there was also runoff
from farms and things like that.
As we know from our own tanks,
when nitrate or phosphate rises too high,
we see an explosion of algae and sign of bacteria.
And the same thing happens in nature.
Reefs that are at high levels of theses chemicals
tend to be overrun with algae,
especially if there's fishing and a lack of herbivores.
The study points out that this is an established fact,
there are many sources.
Reefs near agricultural runoff tend to do worse
than those away from runoff sources.
The author collected 36 fragments,
again, they call them coral nubbins,
so coral nubbins, 36 of them from coral at each site.
And then, half of them they took to the other place
and vice versa.
They let 'em grow for a year.
The seabird location was markedly higher in nitrate,
but phosphate was about the same between the two.
So what would happen in the location with higher nitrate?
That's what they wanted to study.
For reference, the nitrate to phosphate ratio for Namena
was 14 to 33 versus only three to five at Cousteau.
It turns out that the coral grown near the seabirds
grew way faster than the coral
without the seabird nutrient source.
It's really amazing.
Coral grown there grew almost 13 centimeters
in the year they studied versus coral at the other site
only growing five centimeters.
So is this another data point showing the benefits
of having a small amount of nitrogen in our systems?
I think so.
The authors did point out that red-footed booby poop
contains both organic and inorganic nitrogen.
And that does seem to a have a different effect
versus the primarily inorganic nitrogen
that you get from agricultural runoff.
The values that they measured are close
to the recommended levels for our tank, it turns out,
about zero parts per million phosphate,
they measured about two parts per billion,
and about one part per million nitrate.
They measured .713 parts per million.
They also recorded the average PAR values
for the two locations,
which I thought was an interesting data point
that we can use in our tanks.
Both sites were similar.
Namena, the site that had better coral growth,
had a PAR of 613, while Cousteau had a PAR of 568.
So this is higher than we have in most of our reef tanks,
but it's in keeping with some of the recent studies
that we've seen
and that I've talked to you about on my channel,
where you try to mimic the natural light from reefs.
You might be wondering how they knew
that the source of nitrogen in the water was seabird poop
and how they knew that corals were actually using it.
And the answer is actually really interesting,
I encourage you to read the paper.
Seabird poop tends to be much higher in nitrogen-15
than other sources of nitrogen.
So this is interesting because it allows you to then
look at the isotopes of nitrate, of nitrogen,
that end up in the tissues of the coral
and they found that the coral was also high in nitrogen-15
when the coral was grown from a location
near the roosting birds.
Therefore, they knew that the coral
was using the nitrogen that it was getting
from the seabird poop.
We've also talked about the Redfield ratio
in some of my videos
and the author points out that the nitrogen-phosphate ratio
near the seabird colony was much closer to this ratio
than the nonstandard or the non-seabird location.
So this is another interesting piece of data
that shows that we might benefit as reef-keepers
from using the Redfield ratio
in planning the maintenance of our tank
if the desired effect is coral growth rate.
They made no claims of coloration or anything like that.
So the paper is linked down below, it's open access.
I'd really recommend checking it out yourself,
it's a great read.
There is a great discussion.
It's very detailed of the author's results
and the methods included in the paper,
all the breakdown of how it worked and everything.
So that's it for this week.
I hope you enjoyed learning about seabird poop
and I hope it was as interesting for you as it was for me.
I look forward to buying my first bucket of seabird poop
or similar from bulk group suppliers,
something like that, in the future.
It'll give a new meaning to the name Miracle Mud.
Don't forget to like the video
and subscribe if you haven't already.
I'll see you next week, bye.