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TEDxMonterey

Melissa Garren: The sea we've hardly seen

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An average teaspoon of ocean water contains five million bacteria and fifty million viruses -- and yet we are just starting to discover how these "invisible engineers" control our ocean's chemistry. At TEDxMonterey, Melissa Garren sheds light on marine microbes that provide half the oxygen we breathe, maintain underwater ecosystems, and demonstrate surprising hunting skills. (Apologies for the small audio glitches in this video.)

- Melissa Garren, Marine biologist
Melissa Garren is a molecular and marine biologist with a passion for unlocking the mysteries of our ocean's ecosystems and finding new avenues for conservation. Full bio

In the next ten minutes,
we will immerse ourselves
00:05
in an amazing and beautiful marine world
00:08
that's very often overlooked.
00:11
I'd like to take you
on a journey into the sea,
00:13
looking at it from the perspective
of its smallest inhabitants:
00:15
the microbes.
00:19
My goal is that after this short journey,
00:20
you'll share my amazement
at how deeply connected our lives are
00:23
to these microscopic creatures
00:27
and also perhaps my concern
00:29
that these relationships
are often neglected
00:31
when it comes to making decisions
and policies about our oceans.
00:34
When you look out on a clear blue ocean,
00:39
you're actually gazing at
a microbial soup full of vibrant life.
00:42
What you see here
are marine bacteria buzzing about
00:46
and exploring other members
of the marine food web.
00:50
To emphasize how small
this world really is,
00:53
I've added a white line
to most of my slides
00:57
that shows you the thickness
of a single strand of human hair --
01:01
very tiny.
01:04
An average teaspoon of clean seawater
has five million bacteria
01:05
and 50 million viruses in it.
01:10
If I were to scoop up
two gallons of seawater,
01:13
there would be more bacteria
in those two gallons
01:16
than there are people on this planet.
01:18
Take just a moment and think about
01:21
how many gallons might make up an ocean.
01:23
Or maybe I've already made
your stomach turn,
01:26
as you think of all of the seawater
we've each accidentally swallowed
01:28
over the years.
01:32
But luckily, we rarely get sick
from that seawater,
01:33
because most marine microbes
are working for us,
01:36
not against us.
01:39
One of my favorite examples
is that they provide
01:40
half of the oxygen we breathe.
01:43
In middle school, we all learn
to thank the trees.
01:46
And admittedly, they may be
more huggable than the microbes.
01:48
But it turns out
that land plants only create
01:52
a quarter of the oxygen we breathe.
01:55
Another quarter comes
from macroalgae like kelp
01:57
and a full 50% from the microbes.
02:00
Take a deep breath in.
02:03
Thank the trees.
02:05
Take another deep breath in.
02:07
Thank the macroalgae.
02:10
Your next two breaths --
tip your hats to the microbes.
02:12
This picture is of a bacterium
02:15
that happens to be the single most
abundant photosynthesizer
02:17
on our planet.
02:21
It's called, "Prochlorococcus,"
02:23
and this is oceans' oxygen-producing
powerhouse and, I might argue,
02:25
one of the most amazing discoveries
of recent marine microbiology.
02:30
We didn't know it existed until 1988.
02:35
All of human history has depended
on this little microbe
02:37
for the oxygen they breathe every day,
no matter where or when they lived.
02:41
And we've only been aware
of that relationship for a mere 24 years.
02:46
I find that astounding.
02:50
How many more critical
relationships are out there
02:52
that we have yet to discover?
02:54
I see our relationship with marine
microbes as parallel in many ways
02:56
to the relationship we have
with microbes in our gut.
03:00
We've all experienced the wrath
of unhappy gut microbes
03:04
at one point or another,
03:07
perhaps food poisoning or tainted water.
03:08
But we may be less aware of the connection
we have with marine microbes
03:11
and the physical discomforts we can feel
when those communities change.
03:15
As an extreme example: the disease
cholera is caused by a bacterium
03:20
that thrives in the ocean.
03:24
So while most marine microbes
are indeed helping us,
03:26
there do remain plenty that are not.
03:30
Our relationship with the ocean,
much like our gut,
03:32
is dependent on the right
balance of microbes.
03:35
The old phrase, "You are what you eat"
applies to our ocean microbes as well.
03:38
To give you a sense of what
an overfed ocean may look like,
03:43
here are two examples
of me sampling seawater.
03:47
On your left, it's a clean coral reef,
03:49
and on your right is
a nearly dead coral reef
03:52
that has a very intense fish farming
operation in the waters there.
03:55
You'll notice I'm only smiling
in one of these two pictures,
03:59
and in the other one my dive buddy
had to be a whole lot closer
04:03
to capture that image.
04:07
So if we were to take a drop of seawater
from each of these samples
04:09
and put it under the microscope,
04:14
this is what the bacteria and viral
communities would look like.
04:15
So again, clean reef on your left,
fish farm reef on your right.
04:19
As we all have had a feeling of discomfort
04:22
from imbalanced gut microbes,
04:26
a fish swimming through
a part of the ocean
04:29
that has been overfed in this way --
04:31
in this case, by intense aquaculture,
but it could be a sewage spill
04:33
or fertilizer runoff or any number
of other sources --
04:36
that fish will feel
the physical discomforts
04:39
of the ocean microbes being out of whack.
04:41
There may be less oxygen present,
04:44
there may be more pathogens there,
04:46
and there may be toxins
produced by some of these microbes.
04:48
The bottom line is that
from their tiny-scale existence,
04:52
these tiny microbes have
a very large-scale power
04:55
to control how our ocean smells,
04:58
how it tastes,
05:01
how it feels
05:02
and how it looks.
05:03
If you take one idea away
from my talk today, let it be this:
05:06
we have an incredibly important
relationship with these marine microbes
05:10
that have very large-scale consequences,
05:14
and we're just barely
beginning to understand
05:17
what that relationship looks like
05:19
and how it may be changing.
05:21
Just as a physician will have trouble
curing a disease of unknown cause,
05:23
we will have similar trouble
restoring ocean health
05:27
without understanding the microbes better.
05:30
They are the invisible engineers
that control the chemistry of the ocean
05:32
and therefore, what creatures
can live there,
05:35
whether or not it's safe
for us to swim there
05:38
and all of the other
characteristics we sense
05:40
with our eyes, noses and taste buds.
05:43
And the more we pay attention
05:45
to these small but very numerous
members of the ocean,
05:46
the more we're learning
they do indeed respond to human actions,
05:49
such as in this fish farm example.
05:53
Now, as the past few slides
about coral reefs may have suggested,
05:55
I do indeed spend much
of my time as a researcher
05:58
thinking about human-microbe interactions,
06:01
specifically on coral reefs.
06:04
It turns out,
06:06
we're not alone in having
our own protective community of microbes.
06:07
Corals, along with most other
organisms on this planet,
06:10
have their own protective
communities as well.
06:14
However, rather than keeping theirs
on the inside as we do in our gut,
06:17
they keep theirs on the outside,
to protect them from their surroundings
06:21
So what you're seeing here
is a three-dimensional image
06:25
of a live spot on a living coral
with all of its living bacteria,
06:28
that I took with some
exciting technology --
06:33
a high-speed laser-scanning
confocal microscope.
06:35
All of the red circles
are the symbiotic algae
06:38
that live inside the coral tissue,
06:42
turning sunlight and into sugars
they both can use,
06:44
and all of the little blue dots
are the protective bacteria.
06:47
So when I use image analysis software
06:53
to highlight the outer layer
of the coral in white,
06:56
you can see that there are still
some tiny little blue dots
06:59
above that layer.
07:02
And those bacteria are sitting
in a mucus layer,
07:04
which is also part
of the coral's protective layer.
07:07
From the bigger perspective,
07:11
I spend my time thinking
about these relationships,
07:12
because too many reefs are going
from looking like the picture on your left
07:14
to the picture on your right.
07:18
Believe it or not,
07:20
the picture on your right remains
a very popular tourist snorkeling spot
07:21
on the island of Maui,
07:24
even though it's lost most of its coral
cover over the past decade or so.
07:26
Corals are getting sick
all around the globe at alarming rates,
07:29
and we really don't know how or why.
07:32
I see the microbes on the coral reefs,
both the good ones and the bad ones,
07:36
trying to link their micro-scale
behaviors to this big picture
07:41
of: How do we help the reef
that looks like the right
07:45
back towards something
that looks more like the left?
07:49
Or: How do we stop
coral disease from spreading?
07:52
Just over a year ago,
no one had ever seen a view like this.
07:54
This video is a prime example
of making the invisible visible.
07:58
We're looking at a side view
of the same coral as before,
08:04
where the protective layer
meets the seawater;
08:06
so, seawater on your right,
08:09
coral on your left.
08:10
It's incredibly exciting to me
that we can finally see these bacteria
08:12
in real life, in real time,
at their micro scale,
08:16
and learn how they interact
with the world around them.
08:20
Ecologists all over the world
are used to being able
08:23
to grab a pair of binoculars
08:25
and go out and observe
what their study creatures do each day.
08:27
But microbial ecologists
have desperately needed
08:30
breakthroughs in technology,
08:33
such as with this fast confocal,
08:35
to make similar observations.
08:37
I work to find ways that cutting-edge
technologies like this
08:40
can help make the unseen seeable,
08:43
to see marine bacteria in action
and learn how they behave.
08:46
In doing so, we can learn how they respond
08:51
to our actions and our behaviors
and the environment around them
08:53
in ways that will help us
better manage our oceans.
08:57
Another example of how I'm doing this
is by using microfluidics
09:00
to study specifically how pathogens
behave in the ocean.
09:08
The basic idea behind microfluidics
09:11
is that you can use
nanofabrication techniques
09:13
to recreate or mimic
the conditions bacteria experience
09:16
at their own tiny scale in the ocean.
09:20
What you see here is a microfluidic
chamber on a microscope slide
09:23
with a microscope lens underneath it.
09:28
We use high-speed video microscopy
to record bacteria behavior.
09:31
The colored tubing is where
bacteria and seawater flow
09:35
in and out of the device.
09:38
And it's using a device like this
that I recently discovered
09:40
that a known coral pathogen
actually has the ability
09:44
to sniff around the seawater
and hunt for corals.
09:47
Here's the video of in action.
09:51
You'll see all of the pathogens
which are the tiny green dots on the left
09:53
start detecting the coral mucus I put
on the right side of the channel,
09:58
and they swim quickly
over in that direction and stay there.
10:02
Up until now, it was thought
10:06
that a pathogen would need some good luck
to find its host in the ocean.
10:08
But simply by watching
and observing, we can learn
10:13
that these bacteria are very well adapted
to seeking out their victims.
10:16
These micro-channels are bringing
us closer than ever before
10:21
to understanding how bacteria
navigate that big blue ocean.
10:24
It turns out that this pathogen
can even detect the coral mucus
10:28
when I dilute it 20,000 fold.
10:34
So these bacteria are very well adapted
to hunting down these corals.
10:37
I'm currently testing
different environmental conditions
10:43
to see what scenarios make
this pathogen more or less capable
10:47
of hunting corals.
10:51
By learning more
about what triggers the hunt,
10:52
we should be able to find ways
10:55
to help slow down or prevent this disease.
10:57
There's also some evidence
11:00
that the healthy microbes on the coral
can fight off the pathogen
11:02
if the conditions are right.
11:07
So, one final image of a coral
and its healthy bacteria.
11:09
I hope you've enjoyed this short journey
into our microbial oceans
11:13
and that the next time you
look out at the sea,
11:16
you'll take in a deep breath
of fresh ocean air and wonder:
11:19
What else are all
of the unseen microbes doing
11:22
to keep us and our oceans healthy?
11:25
Thank you.
11:27
Translated by TED Translators Admin
Reviewed by Camille Martínez

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About the speaker:

Melissa Garren - Melissa Garren, Marine biologist
Melissa Garren is a molecular and marine biologist with a passion for unlocking the mysteries of our ocean's ecosystems and finding new avenues for conservation.

Why you should listen

Melissa Garren studies marine microbes to better understand how pollution and climate change are destroying coral reefs and effecting our environment. Working under a fellowship from the Smithsonian Tropical Research Institute she began using molecular techniques to study microbial life in the ocean. At the Costa Rican wildlife refuge, Melissa helped spearhead a long-term monitoring project as well as educational initiatives. After recently receiving her Ph.D. in Marine Biology from the Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, she is now using microfluidic technology to understand the living ecosystem of coral reefs in a postdoctoral position at the Massachusetts Institute of Technology.

More profile about the speaker
Melissa Garren | Speaker | TED.com