The sea we’ve hardly seen: Melissa Garren at TEDxMonterey

The sea we’ve hardly seen: Melissa Garren at TEDxMonterey

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

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