SPEAKER: Coral reefs are one of
the most spectacular ecosystems
found in nature.
Hosts to numerous
biological communities,
they are important
havens of biodiversity.
And a valuable food source
for over 500 million people.
But as Earth's climate
warms, so do the oceans,
bringing heat stress
to coral communities.
When water temperatures
get too warm,
coral species may respond by
expelling their symbiotic algae
in a process called bleaching.
Repeated or prolonged
bleaching can
lead to the death of
entire coral colonies.
Marine biologist
Steve Palumbi is
studying how different
coral populations
respond to heat stress
caused by warming oceans.
He regularly travels to
Ofu, a tiny island in Samoa,
for his fieldwork.
STEVEN PALUMBI: Ofu island
and the lagoon behind the reef
here is one of the best coral
laboratories in the world.
These back reef lagoons heat
up to an extraordinary degree
for a coral reef.
They heat up to 32, 33,
34 degrees centigrade.
That's above the temperature
which most corals will bleach
and die, yet these lagoons
are full of thriving, growing
corals of many, many species.
So the question is, how
do these corals do it?
How do they live in
such warm temperatures?
SPEAKER: To answer
these questions,
Palumbi and his
colleagues conducted
a controlled experiment,
devising a way
to apply heat stress to
the corals in the lab.
STEVEN PALUMBI: First, we had
to build a standardized stress
tank so that we
could expose corals
from different parts of the
reef to exactly the same stress.
SPEAKER: Palumbi took
corals of the same species
from two different
parts of the reef,
one living in a
warmer pool of water
and the other in a
cooler pool, and put them
in the stress tanks.
When grown and measured
in these tanks,
corals from the warmer pool were
more resistant to bleaching.
But could corals
from the cooler pool
become more heat resistant
if given time to acclimate
to warmer temperatures?
Another experiment was needed.
STEVEN PALUMBI: So
what's cool about corals
is you can take them, break
them into two fragments.
They're genetically identical
clones of one another.
You can grow them in
different environments
and then retest them.
SPEAKER: Palumbi
transplanted corals
from the cooler Ofu pool
into the warmer pool.
He let them grow for three
years and then tested them again
in the stress tanks.
This time, the
transplanted coral
were more resistant to bleaching
than their cooler ancestors,
but still not as heat resistant
as the original warmer
pool corals.
What makes the
warmer pool corals
more resistant to heat stress?
The answer is in their genes.
STEVEN PALUMBI:
The corals that are
living in the warmer pool
have better heat tolerance
genes, and so they have a
leg up on heat tolerance
that the corals living in
the cooler pool don't have.
So as a consequence of 5,
6, 7 years of work now,
we have found that corals can
change their heat tolerance
and acquire higher
heat resistance,
but that having the
right genes helps too.
A combination of
acclimation and adaptation
is what gives these Ofu
corals such high heat
resistance in the warmer pool.
SPEAKER: Could these
scientific findings
be applied to
saving or repairing
damaged coral reefs affected
by heat and other stresses?
To answer this question,
Palumbi and graduate student,
Megan Morikawa, have
started another experiment.
MEGAN MORIKAWA: This initial
project, this reef restoration
project, is really
a big experiment.
It's a big scientific experiment
to see if different species
transplant better than others.
To see if different individuals
within those species
transplant better than others.
STEVEN PALUMBI: Now the
new spot in this case
is across the mountain on
the other side of the island
at a reef called Sili.
It was a beautiful
reef 20 years ago.
It got slammed by a hurricane.
Corals, they're all rubble.
Suppose we try to
restore that reef.
And the experiment, which
we've just started days ago,
is to ask whether or not
corals from the warmer
part of the reef
transplant and grow better
than corals from the
cooler part of the reef.
And we'll monitor them
over the next year
to see who survives, who grows,
and then who grows best of all.
MEGAN MORIKAWA: So I've
made it a goal of my career
to try and bridge the gap
between research sciences
and real world applications.
And this is a project that is
attempting to do just that.
We're trying to bring a
good project to a place that
has special coral.
That has the management
agencies in place
in order to understand the
importance of the research
that we're doing.
So it's a very fortunate
dissertation project
to work on.
I consider myself
lucky every day.
STEVEN PALUMBI: So one of
the most important things
that corals have going
for them actually
is that people around the
world care about them.
They recognize the
productivity of reefs
and the importance of them to
the people that live there.
The way they protect
shorelines from erosion.
Their beauty.
And that kind of
attention, like attention
on tropical rainforests,
results in people asking, well,
what can we do to save
these amazing ecosystems?
That's a really
important first step.
Because with that
kind of willpower
and the attention of the
world on the problem,
then maybe we have a
chance of fixing it.
