- Do you ever look at your controller's pH
or temperature graph and wonder if those swings are normal?
I often tell people that stability is key
in keeping a healthy reef full of SBS coral.
And we can look at these graphs
and they're anything but stable.
Hi, guys and girls.
I'm ReefMan and today we'll be talking
about a study that came out
which looks at the relationship between pH,
temperature, depth, and the time of day.
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It's great to have you back with me.
So, if you're interested in the paper itself,
it is called Diel temperature and pH variability scale
with depth across diverse coral reef habitats
and the link to it is down below, so check it out.
Don't get tripped on the word diel either.
It just means that they're gonna look
at a 24-hour window of time in the paper.
In fact, the team deployed pH and temperature sensors
to five different reefs
in both the Atlantic and Pacific Oceans.
They measured the pH and temperature of the water,
as well as the time and the depth
that they had placed the sensors at.
The research team collected data
from all of these different sensor arrays,
for between 5.5 to 17.5 days at each location.
The sensor arrays were actually resting
on the very bottom of the water on the ocean floor,
not suspended in the water column like you might expect,
maybe from a buoy or something like that.
You can think of short-term changes
in water chemistry and temperature almost like ocean weather
and, as you know, a cold front kind of moves through
where you live and the weather gets colder.
Maybe it's windy as the front passes.
Maybe there's some rain or even snow as it passes.
Well, the same sort of stuff happens in the ocean.
Ocean currents move around the water.
Upwellings come up from the depths
and bring cooler water to the surface.
And so obviously all of this has an impact
on both pH and temperature.
Of course, we don't have upwellings in our reef tanks,
so there's gotta be something else going on, and there is.
Biological processes take place.
Algae grows, it uses CO2.
Coral grows, it uses calcium, carbonate, bicarbonate,
and other chemicals that are in the water.
And all of this has an impact on your tank's pH.
And, of course, like mine are, your lights are on
and they're the main reason your tank heats up
during the day.
And that is just the same.
The sun is the main reason that the ocean heats up.
And, in fact, the ocean is warmest in the afternoon,
just like our tank is.
In the study, the pH varied based on the time of day,
from about 0.03 to 0.46 units
and so that means that my tank,
which maxed out yesterday at 8.03, is within the wild range,
since the minimum after was 7.84,
which is only a difference of 0.19 units.
Temperature was more stable, as you might expect,
but it too varied and it varied between 0.1 degree
and 5.3 degrees Celsius.
That makes me feel better about my temperature,
which, of course, I measure in Fahrenheit, not Celsius.
But I have a maximum temperature
of about 81, 82 each afternoon
and I only have about a two degree swing,
Fahrenheit, of course.
So, what is the impact of all of this
on the coral that lives there?
In fact, there is an impact.
It seems like short-term swings in temperature and pH
can actually mitigate larger swings,
like those that are being caused by climate change,
up to a certain point at least.
Also, corals exposed to pH swings tend to calcify faster
and they even grow larger than corals
which were not exposed to recurring changes in pH,
which I thought was pretty cool.
You wouldn't guess that.
Interestingly, the authors also found
a direct linear relationship between pH, temperature,
and the depth that the measurements were taken at.
And so using this model, they can predict
what the daily range of values might be for another reef
if they just know the depth of the water.
And so they did that.
They used another paper that provided 118 measurements
from other reefs and their model held.
I thought that this paper was really neat.
It's interesting that temperature and pH vary
based on depth.
You would think that it moves around
and it would all be the same,
but it's even more interesting
to see that the daily swings that see
from our own reef tanks are not completely out-of-line
with what happens on a wild reef.
It's also interesting that the corals
that are subjected to more variation and change
are actually more resilient
against bleaching and climate change than the change itself.
So I guess some variation in our parameters
is actually a good thing.
It'll harden and make our corals more hearty.
So thanks for watching.
I really hope you enjoyed the video.
Again, there's a link down below
if you want to check the paper out.
I would suggest you do that.
Take a moment to hit the subscribe button,
if you're not already a subscriber.
And if you are, thank you, thank you again.
So I'll see you next time.
Bye!