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- Welcome everyone to the second day

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of our 42nd Darwin Festival.

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We're just letting people populate.

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I guess today, Dr. Hanny
Rivera will be introduced

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in a moment by my colleague,
Dr. Thea Popolizio,

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our colleague in the Biology Department.

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We just hold on a few more moments

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just to let people move into
the virtual room with us.

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All right, Dr. Popolizio,
I'll hand it over to you.

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- Hello, everyone, and
welcome to Darwin Festival.

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Many of you might be actually happy today

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to be joining us from your
couch on the snowy afternoon.

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I'm still thrilled to be
introducing Dr. Hanny Rivera

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for today's second lecture.

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Dr. Rivera is a molecular ecologist

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and evolutionary biologist.

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She studies population genetics

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and gene expression and
reef building corals,

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and is particularly
interested in understanding

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how corals respond to
environmental change,

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what makes some corals more resilient

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to environmental stressors,

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and how Earth's reef ecosystems
may fare in the near future.

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Dr. Rivera completed a bachelor's degree

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in biology at Harvard College

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and a PhD in biological oceanography

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at the joint program of MIT

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and Woods Hole Oceanographic Institution.

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She is currently a postdoctoral scholar

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and associate lecturer
at Boston University

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in the Sarah Davies Marine
Population Genomics Lab.

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And in addition to teaching and research,

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Dr. Rivera is active
in scientific outreach

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and has led and co-founded
a number of events

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and organizations that support

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environmental sustainability
and science communication.

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I am lucky to have crossed
paths with Dr. Rivera years ago

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when we were both students
living and conducting

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field research in the small
island community of Bermuda.

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So it's with great pleasure

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that I introduce her to you today,

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and I hope you'll join me in spirit

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from behind your screen in
giving her a warm welcome

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to Salem State and to Darwin Festival.

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- Thank you so much for
that introduction, Thea.

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Certainly wishing we were
back in Bermuda right now.

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Okay, I'm gonna go ahead and start this.

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So thank you, everyone, for
being here this afternoon.

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They told me the number of
participants before we started,

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and now I'm a little overwhelmed.

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So thank you for all the
varied interest in this work.

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Hopefully, today, you will leave

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with a better understanding of corals,

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why we care about them,

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and some of the threats and
conditions that they're facing.

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I've tried to keep this
talk fairly big picture,

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but if you have any questions
about specific techniques

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or data analysis or anything like that,

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please feel free to ask those
questions in the Q and A.

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So first, I'm gonna be talking to you

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about why corals matter to us.

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They're actually really
important for humans.

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The kind of magic of
coral is somewhat grounded

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in this amazing symbiosis that they have

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with the single cell algae
that live inside their tissue.

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So I'll talk to you a little bit

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about how that symbiosis works
and why it's so efficient.

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And then I'll move on to
some not so wonderful news,

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but very important things to know

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about how climate change
is impacting reef health.

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And then I'll share a
little bit of my research

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on trying to understand which reefs

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might fare best in the coming decades,

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where we might find resilient reefs

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that are actually able of tolerating

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some climate change stressors
and what that can mean

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for the future of reefs more generally.

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So first, I'd like to talk
about the many services

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that coral reefs provide,

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and these really range
from economic services

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such as coastal protection
to tourism generation, right?

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They're beautiful ecosystems to explore

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and they drive a lot of tourism

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to many countries and coastlines,

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and they also provide
a good number of fish

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that we actually eat.

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There is also a suite

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of biological benefits that they offer.

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Coral reefs are often touted

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as being the rainforest of the ocean.

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And this is because they
host a plethora of species.

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So there's thousands of species

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that live on coral reef environments.

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And there's even more species
that even if they don't

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spend their entire life on a coral reef,

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spend some portion of their
life in a coral reef habitat,

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largely as juveniles.

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In addition, they also offer
several societal benefits,

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including drug discovery and
pharmaceutical capabilities.

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So for instance, there are
several cancer and HIV medicines

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that have been developed from organisms

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that live on coral reef ecosystems.

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And they also just offer us a
really wonderful environment

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to explore and learn and gain
an appreciation for nature.

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The total value of all of these services

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is estimated to be about
$11 trillion annually.

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And this is under just kind
of baseline conditions.

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When there are things
like mega hurricanes,

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the value of the coastal
protection that they offer

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increases substantially, for instance.

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And they're also critical
for millions of people.

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So this is a map that
I generated for a paper

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I recently wrote about coral
reef ecosystem services,

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and it shows coral reefs
here in red as red dots.

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You can see that they're mostly
concentrated in the tropics,

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'cause they like warm waters,

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though as you'll learn
later, not too warm.

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But there are hundreds of
thousands and millions of people

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that live in cities that
are near coral reefs

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and they use these reefs to fish for food

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that they need every
day to generate tourism

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and economics for their countries,

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as well as coastal
protection against storms.

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So coral reefs are really
important across the globe.

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You can notice in particular
that the Indo-Pacific region

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has a very high density
of both coral reefs

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and people that live on or near reefs.

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In the United States, most of
our coral reef environments

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are in the either Hawaiian archipelago

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or in the Florida Keys,

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as well as a number of US territories

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that are in the Central Pacific,

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one of which I'll be talking
about a little later today.

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Now, corals are really interesting

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because they form these
massive structures.

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Corals are calcifying organisms.

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So they literally make
rock that forms reefs,

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and these reefs are so massive
they can be seen from space.

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On the left is a satellite
image from the Florida Keys

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that shows the Florida Reef Tract,

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which is one of the biggest
barrier reefs in the planet.

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And this whole section that you see here

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is essentially that shelf
that has been formed,

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or that barrier that has
been formed by the reefs

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that have grown to create the Florida Keys

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over the last several millennia.

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On the right hand side
is just a short segment

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of the Great Barrier Reef in Australia,

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which is the world's
largest barrier reef system.

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And these kind of neon blue smatterings

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that you see here are all reefs

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that are creating that barrier system.

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Now, you might imagine that
these reef environments

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almost look like seawalls.

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And in fact, they actually offer

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a lot of coastal protection against storms

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by acting as a seawall, essentially.

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They take a huge amount of wave energy

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whenever there is a
storm or say a hurricane,

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as is often the case in
Florida or Australia,

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in which case, they're typhoons.

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But they're really important
for that aspect alone.

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So important in fact, that recently,

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the Department of Defense
is trying to fund projects

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to develop reefs artificially
that might mimic coral,

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the protection that corals already offer.

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Okay, so now I've hopefully convinced you

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that corals are really important to us,

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that we should care about them.

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Now, I'd like to tell you a
little bit about what they are.

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So corals are animals,

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but they're a little bit more than that.

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So here in this picture,
you're seeing a coral colony.

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That's this entire kind of lettuce-looking

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brown structure that you see here.

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And this coral colony
is actually for and by

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an amalgamation of these individual polyps

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that you see in this closeup here.

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And corals are related to jellyfish.

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So you might notice that this polyp

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kind of looks like a jellyfish

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that's been flopped on its back

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and has its little tentacles in the air.

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And that's essentially what polyps are.

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Now, the coral polyp essentially

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grows this colony by
reproducing itself asexually.

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So it just clones itself
from the initial polyp

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that settles as a baby coral

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and then grows over time to form

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these really amazing structures.

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And part of the reason
that it's able to grow

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and generate these reef
environments is due to the symbiosis

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or this very beneficial relationship

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that it has with multiple partners.

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One these partners is a single cell algae

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called Symbiodiniaceae is the genus,

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they're dinoflagellates.

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They're a type of phytoplankton.

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And these algae live inside
the tissue of the corals.

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In addition, they also
host, similar to humans,

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which have a very healthy, say
for instance, gut microbiome,

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corals have all sorts
of bacteria that live

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both in and on its tissue
that also help stabilize

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both the relationship with the symbiont,

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as well as provide additional nutrients

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and benefits for the coral itself.

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Now, collectively, these three partners

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are called the holobiont,

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because they are kind
of this meta-organism.

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It's not just the animal,

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the animal needs the
plant, needs the bacteria

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in order to actually function and survive.

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Now, the relationship with the algae

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is one of the more sensitive partnerships.

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And so I'm gonna spend
a little bit of time

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talking about how that works
and why it's under threat.

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So for the rest of the talk,
I'll just refer to the algae

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as symbionts as opposed
to saying Symbiodiniaceae,

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which is a little bit of a mouthful.

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So this relationship is really
foundational to the coral

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because the algae which
are tiny microscopic plants

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are using sunlight and
they're creating sugars

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through photosynthesis that
they then provide to the coral.

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So what the coral has managed
to do over eons of evolution

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is essentially create a relationship

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that gives it an in-house factory.

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So it's constantly
being fed by these algae

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that it's hosting in its tissue.

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In exchange, the coral
is providing nutrients

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and shelter for the algae.

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We know plants need fertilizer to grow

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and be happy and healthy,

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so that's essentially the role
that the coral is providing.

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It's giving the nutrients,

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the correct amount of
nitrogen and phosphorus

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and other amino acids
and things that it needs

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to grow and photosynthesize properly.

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Now, a lot of what we know
about this relationship

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comes from either metabolic studies

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that have looked at exactly what sugars

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are being transferred between
the symbiont and the coral,

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or gene expression studies of which

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I recently started to get my hands into,

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that look at what genes are
differentially expressed,

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meaning what genes are turned on or off

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and thereby creating the proteins

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that those genes encode for

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when a coral is in symbiosis

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or when it doesn't have that symbiont.

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So here, I've done a study recently

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with a coral called Oculina arbuscula,

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which is one of the few
corals that can actually

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live happily with and
without its symbionts.

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And I've asked what
genes are differentially

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expressed in these two symbiotic states.

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And one of the things that we see

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00:11:33,070 --> 00:11:35,440
is that symbiotic fragments of this coral

258
00:11:35,440 --> 00:11:38,210
heavily upregulate metabolic processes,

259
00:11:38,210 --> 00:11:41,340
which makes sense, because
it's part of this exchange

260
00:11:41,340 --> 00:11:45,483
of sugars and nutrients that
really drive the symbiosis.

261
00:11:46,450 --> 00:11:48,180
So here are just a couple of,

262
00:11:48,180 --> 00:11:49,730
these are called Gene Ontology terms,

263
00:11:49,730 --> 00:11:51,830
which are general categories
for what those genes

264
00:11:51,830 --> 00:11:54,260
are related to what types of processes.

265
00:11:54,260 --> 00:11:55,810
And you can see that a lot of the genes

266
00:11:55,810 --> 00:11:57,140
that are differentially regulated

267
00:11:57,140 --> 00:11:59,310
are involved in the process of lipids

268
00:11:59,310 --> 00:12:01,980
and amino acids and carbohydrates

269
00:12:01,980 --> 00:12:04,433
such that this symbiosis
can actually prosper.

270
00:12:06,530 --> 00:12:08,060
Now, this symbiosis also allows

271
00:12:08,060 --> 00:12:10,840
the coral to form its skeleton.

272
00:12:10,840 --> 00:12:14,690
Biomineralization is an expensive
energy intensive process.

273
00:12:14,690 --> 00:12:17,870
And it's really thought that
the evolution of symbiosis

274
00:12:17,870 --> 00:12:20,790
is what gave corals the
kind of energetic push

275
00:12:20,790 --> 00:12:23,030
that they needed to really be able to form

276
00:12:23,030 --> 00:12:25,423
and biomineralize at
the scale that they do.

277
00:12:27,350 --> 00:12:29,660
Now, this relationship
is extremely beneficial

278
00:12:29,660 --> 00:12:31,170
for both the symbiont and the coral,

279
00:12:31,170 --> 00:12:33,270
but unfortunately, it's very sensitive,

280
00:12:33,270 --> 00:12:34,923
and it can be easily perturbed.

281
00:12:36,410 --> 00:12:38,380
One of the things that can disrupt it

282
00:12:38,380 --> 00:12:40,160
very quickly is temperature.

283
00:12:40,160 --> 00:12:42,190
And so many of you may have heard

284
00:12:42,190 --> 00:12:44,060
of a phenomenon called bleaching.

285
00:12:44,060 --> 00:12:45,590
It's been happening more and more.

286
00:12:45,590 --> 00:12:49,510
And what it means is that
there's a temperature increase,

287
00:12:49,510 --> 00:12:51,690
and this temperature
increase essentially sends

288
00:12:51,690 --> 00:12:56,590
the photosynthesis mechanism
of the symbiont into overdrive.

289
00:12:56,590 --> 00:12:58,620
So now, the coral is left with this

290
00:12:58,620 --> 00:13:01,590
kind of overheating
engine inside its tissue

291
00:13:01,590 --> 00:13:04,450
that it can no longer really
control or regulate properly.

292
00:13:04,450 --> 00:13:06,900
And so it ends up either the cells

293
00:13:06,900 --> 00:13:09,100
that have the symbiont in them die,

294
00:13:09,100 --> 00:13:11,490
or the coral expels the symbionts.

295
00:13:11,490 --> 00:13:14,810
And in doing so, it
loses its pigmentation,

296
00:13:14,810 --> 00:13:16,350
'cause most of the color of the coral

297
00:13:16,350 --> 00:13:18,870
comes from these symbiotic cells.

298
00:13:18,870 --> 00:13:20,720
And what's left behind is a coral

299
00:13:20,720 --> 00:13:22,330
that looks like you put it in bleach

300
00:13:22,330 --> 00:13:23,630
and it lost all its color.

301
00:13:24,930 --> 00:13:26,930
The bleached coral is still alive,

302
00:13:26,930 --> 00:13:28,600
but the coral tissue is transparent.

303
00:13:28,600 --> 00:13:30,590
And so what you're seeing is the skeleton

304
00:13:30,590 --> 00:13:33,260
that it's made through that clear tissue.

305
00:13:33,260 --> 00:13:35,270
Now, bleached corals can die very quickly,

306
00:13:35,270 --> 00:13:37,820
in which case they just
leave behind the skeleton

307
00:13:37,820 --> 00:13:40,010
and the skeleton can be easily overgrown

308
00:13:40,010 --> 00:13:44,360
by say bacterial biofilms
or other big algae.

309
00:13:44,360 --> 00:13:47,840
And they transform a reef into
a really healthy ecosystem

310
00:13:47,840 --> 00:13:51,480
that looks like the one on
the left to not very healthy,

311
00:13:51,480 --> 00:13:53,390
not very biodiversity ecosystem,

312
00:13:53,390 --> 00:13:54,640
such as the one on the right,

313
00:13:54,640 --> 00:13:58,810
which is essentially just a
giant coral rubble cemetery

314
00:13:58,810 --> 00:14:00,950
covered with filamentous
algae that are not really

315
00:14:00,950 --> 00:14:04,393
providing the same kind of
ecosystem services as before.

316
00:14:07,020 --> 00:14:10,140
Now, as I mentioned, the
bleached corals are still alive,

317
00:14:10,140 --> 00:14:11,720
but they're starving, right?

318
00:14:11,720 --> 00:14:13,823
They've lost their main source of food.

319
00:14:14,800 --> 00:14:17,740
And what this means is that
they have very short window

320
00:14:18,820 --> 00:14:20,190
during which they can actually recover

321
00:14:20,190 --> 00:14:22,613
those symbionts and
survive a bleaching event.

322
00:14:26,128 --> 00:14:27,980
And in order for that recovery to happen,

323
00:14:27,980 --> 00:14:29,403
it really needs to,

324
00:14:30,770 --> 00:14:33,370
the temperatures really
need to come back down.

325
00:14:33,370 --> 00:14:35,930
Now, oftentimes when
there are bleaching events

326
00:14:35,930 --> 00:14:37,340
that trigger coral bleaching,

327
00:14:37,340 --> 00:14:41,600
they're often usually heating events

328
00:14:41,600 --> 00:14:43,850
that last several weeks, sometimes months.

329
00:14:43,850 --> 00:14:45,370
And these are particularly dangerous,

330
00:14:45,370 --> 00:14:46,930
because they can then kill off

331
00:14:46,930 --> 00:14:48,963
a really large percentage of corals.

332
00:14:50,810 --> 00:14:53,050
And that's exactly what's
been happening more recently.

333
00:14:53,050 --> 00:14:54,640
So bleaching events are getting worse.

334
00:14:54,640 --> 00:14:55,710
They're killing more corals

335
00:14:55,710 --> 00:14:58,700
and they're becoming more
widespread and more frequent.

336
00:14:58,700 --> 00:15:00,500
Here, on the right, I'm showing a graph

337
00:15:00,500 --> 00:15:03,700
that depicts the global
ocean heat content,

338
00:15:03,700 --> 00:15:06,290
so how much heat is being
trapped in the ocean.

339
00:15:06,290 --> 00:15:09,210
You can see that that
number has been increasing

340
00:15:09,210 --> 00:15:13,830
since about the 1970s or so,
and it's going up quite a lot.

341
00:15:13,830 --> 00:15:15,150
And now, what this has led to

342
00:15:15,150 --> 00:15:19,020
is what have been called
global mass bleaching events,

343
00:15:19,020 --> 00:15:20,790
which means that the waters in the ocean

344
00:15:20,790 --> 00:15:23,850
have gotten warm enough
at such a wide scale

345
00:15:23,850 --> 00:15:26,110
that we see bleaching happening

346
00:15:26,110 --> 00:15:28,060
at reefs all across the planet.

347
00:15:28,060 --> 00:15:30,450
So there's bleaching in
reefs in the Red Sea,

348
00:15:30,450 --> 00:15:31,670
there's bleaching in the Caribbean,

349
00:15:31,670 --> 00:15:33,210
there's bleaching in the Central Pacific,

350
00:15:33,210 --> 00:15:34,660
there's bleaching in
the Great Barrier Reef,

351
00:15:34,660 --> 00:15:39,110
there's bleaching in
the Azores, everywhere.

352
00:15:39,110 --> 00:15:41,060
And now, the first mass bleaching event

353
00:15:41,060 --> 00:15:43,540
that coral scientists really recorded

354
00:15:43,540 --> 00:15:45,610
was in the early 1980s.

355
00:15:45,610 --> 00:15:48,570
And since then, there's
been several other,

356
00:15:48,570 --> 00:15:50,230
even larger events.

357
00:15:50,230 --> 00:15:51,590
And you can notice here at the end

358
00:15:51,590 --> 00:15:53,650
that both in 2010 and 2015,

359
00:15:53,650 --> 00:15:55,690
that's a very short time lag.

360
00:15:55,690 --> 00:15:58,240
And so they're becoming
more and more frequent.

361
00:15:58,240 --> 00:15:59,880
And the amount of time

362
00:15:59,880 --> 00:16:02,310
between bleaching events
is getting shorter.

363
00:16:02,310 --> 00:16:03,940
And actually since 2015,

364
00:16:03,940 --> 00:16:06,660
we've seen a couple of other
really big bleaching years.

365
00:16:06,660 --> 00:16:09,410
Not at the scale of 2015,
that's still quite worrisome.

366
00:16:13,060 --> 00:16:16,370
Now, another threat that
corals are facing today

367
00:16:16,370 --> 00:16:19,880
is that their skeletons are
made of calcium carbonate.

368
00:16:19,880 --> 00:16:24,360
Now, this mineral is
really sensitive to pH.

369
00:16:24,360 --> 00:16:26,750
And because we're emitting
CO2 into the atmosphere

370
00:16:26,750 --> 00:16:29,330
and that CO2 is mixing
in with ocean water,

371
00:16:29,330 --> 00:16:32,270
that drives a chemical reaction
that actually is decreasing

372
00:16:32,270 --> 00:16:35,290
the overall pH of the ocean's waters.

373
00:16:35,290 --> 00:16:37,170
And this decline in pH makes it

374
00:16:37,170 --> 00:16:39,460
much harder for corals to grow.

375
00:16:39,460 --> 00:16:44,460
It makes it such that
biomineralization process,

376
00:16:44,510 --> 00:16:46,590
which was already very energy intensive,

377
00:16:46,590 --> 00:16:48,090
becomes even costlier, right?

378
00:16:48,090 --> 00:16:50,040
You have to essentially
drive the formation

379
00:16:50,040 --> 00:16:53,330
of calcium carbonate with fewer resources

380
00:16:53,330 --> 00:16:55,690
and against a much stronger gradient.

381
00:16:55,690 --> 00:16:58,920
It also makes it such that
coral that for instance

382
00:16:58,920 --> 00:17:01,470
might've died and has a
skeleton that it left behind,

383
00:17:01,470 --> 00:17:02,950
that skeleton is gonna dissolve

384
00:17:02,950 --> 00:17:05,780
much more quickly also in lower pH.

385
00:17:05,780 --> 00:17:08,710
So here, I'm showing you pictures
of a coral that was grown.

386
00:17:08,710 --> 00:17:11,560
So this is a baby coral
during its initial sediment,

387
00:17:11,560 --> 00:17:13,060
when it forms its first polyp.

388
00:17:14,853 --> 00:17:17,800
It was grown in low pH or higher pH.

389
00:17:17,800 --> 00:17:20,040
And you can see that as you lower the pH,

390
00:17:20,040 --> 00:17:21,970
there's basically no skeleton there.

391
00:17:21,970 --> 00:17:23,990
It becomes really difficult for that coral

392
00:17:23,990 --> 00:17:26,070
to actually form the restructure

393
00:17:26,070 --> 00:17:29,223
that is the basis for
this entire ecosystem.

394
00:17:31,980 --> 00:17:35,350
So I've mentioned two main
threats that corals are facing,

395
00:17:35,350 --> 00:17:36,930
acidification and temperature.

396
00:17:36,930 --> 00:17:38,630
Both of these are directly linked

397
00:17:38,630 --> 00:17:40,800
to the increase of greenhouse gases

398
00:17:40,800 --> 00:17:44,070
and in particular of carbon
dioxide in our atmosphere.

399
00:17:44,070 --> 00:17:47,370
There are also other threats
that corals are facing.

400
00:17:47,370 --> 00:17:50,600
So for instance, corals can also get sick.

401
00:17:50,600 --> 00:17:53,110
There are the variety
of bacteria and viruses

402
00:17:53,110 --> 00:17:56,970
that can infect coral
and cause tissue damage.

403
00:17:56,970 --> 00:18:00,230
These often interact
negatively with temperature.

404
00:18:00,230 --> 00:18:01,660
So for instance, there are pathogens

405
00:18:01,660 --> 00:18:03,870
that become more virulent
at higher temperatures

406
00:18:03,870 --> 00:18:05,510
and therefore can infect corals

407
00:18:05,510 --> 00:18:07,733
more easily and spread more quickly.

408
00:18:08,830 --> 00:18:10,420
There are also runoffs.

409
00:18:10,420 --> 00:18:12,830
So if, for instance,
say there's a coral reef

410
00:18:12,830 --> 00:18:16,980
near an agricultural
area or a golf resort,

411
00:18:16,980 --> 00:18:19,130
all that fertilizer gets into the water

412
00:18:19,130 --> 00:18:21,640
and it disrupts the
nutrient cycling in the reef

413
00:18:21,640 --> 00:18:25,030
and it can disrupt the
symbiotic relationship as well

414
00:18:25,030 --> 00:18:26,453
and lead to coral bleaching.

415
00:18:27,303 --> 00:18:30,160
In addition, there is overfishing.

416
00:18:30,160 --> 00:18:32,840
That algae that grows on
the dead coral skeleton,

417
00:18:32,840 --> 00:18:34,820
it's always trying to grow on the reefs.

418
00:18:34,820 --> 00:18:36,090
But when the coral is alive,

419
00:18:36,090 --> 00:18:38,063
it can kind of maintain its growth

420
00:18:38,063 --> 00:18:41,230
in such a way that it
out-competes the algae.

421
00:18:41,230 --> 00:18:43,630
But one of the things that
facilitates that competition

422
00:18:43,630 --> 00:18:46,350
is having herbivorous fish
that eat the algae away

423
00:18:46,350 --> 00:18:49,030
and keep it from growing over the coral.

424
00:18:49,030 --> 00:18:50,840
When reefs are over-fished,

425
00:18:50,840 --> 00:18:53,020
then those herbivorous fish are gone,

426
00:18:53,020 --> 00:18:55,930
and now the algae actually have an edge

427
00:18:55,930 --> 00:18:58,460
and they can overgrow the coral as well.

428
00:18:58,460 --> 00:19:02,170
So this is all a little bit
depressing, and I'm sorry,

429
00:19:02,170 --> 00:19:03,710
but it's kind of the truth.

430
00:19:03,710 --> 00:19:05,490
So I do wanna share it with you.

431
00:19:05,490 --> 00:19:07,880
There are lots of threats
that corals are facing.

432
00:19:07,880 --> 00:19:11,910
Now, I don't wanna leave you
on a completely bad note.

433
00:19:11,910 --> 00:19:13,970
So I do wanna talk a little bit

434
00:19:13,970 --> 00:19:16,650
about some of the hope, right?

435
00:19:16,650 --> 00:19:18,230
So we have all these threats.

436
00:19:18,230 --> 00:19:21,220
They are not really in the best prognosis,

437
00:19:21,220 --> 00:19:23,400
but can they actually make it?

438
00:19:23,400 --> 00:19:25,070
And I would like to
say that yes, they can.

439
00:19:25,070 --> 00:19:27,970
But we humans need to act quite fast

440
00:19:27,970 --> 00:19:30,420
to address a number of these issues.

441
00:19:30,420 --> 00:19:32,730
And in addition, we also
need to act quite fast

442
00:19:32,730 --> 00:19:35,500
to better understand symbiosis
and better understand

443
00:19:35,500 --> 00:19:37,610
what are the differences
between the corals

444
00:19:37,610 --> 00:19:39,710
that don't seem to be as effective

445
00:19:39,710 --> 00:19:41,170
versus those that are really suffering

446
00:19:41,170 --> 00:19:42,793
from some of these stressors.

447
00:19:44,410 --> 00:19:45,243
Okay.

448
00:19:49,200 --> 00:19:51,580
So now, I'd like to turn and share

449
00:19:51,580 --> 00:19:54,120
a couple of stories from
the work that I've done

450
00:19:54,120 --> 00:19:57,520
throughout my research career so far.

451
00:19:57,520 --> 00:20:00,730
And a lot of this has been
focused on resilient reefs.

452
00:20:00,730 --> 00:20:02,473
So what do I mean by resilient?

453
00:20:03,410 --> 00:20:04,610
This can mean a couple of things.

454
00:20:04,610 --> 00:20:06,190
So for instance, it might be a reef

455
00:20:06,190 --> 00:20:08,440
that's not really expected to get as hot,

456
00:20:08,440 --> 00:20:09,930
and that might be because maybe

457
00:20:09,930 --> 00:20:11,630
it's a more northern latitude reef,

458
00:20:11,630 --> 00:20:14,750
and so the waters are actually
much cooler right now.

459
00:20:14,750 --> 00:20:16,980
So by the time temperatures increase

460
00:20:16,980 --> 00:20:18,150
one, two, three degrees,

461
00:20:18,150 --> 00:20:21,920
it'll still be in a relatively
normal range for corals.

462
00:20:21,920 --> 00:20:23,120
So for instance, in Japan,

463
00:20:23,120 --> 00:20:25,220
we're seeing that that's often the case

464
00:20:25,220 --> 00:20:27,550
and there's even range
expansions into areas

465
00:20:27,550 --> 00:20:30,220
that were previously cooler
that have now warmed.

466
00:20:30,220 --> 00:20:33,760
And we're seeing corals starting
to grow within those areas.

467
00:20:33,760 --> 00:20:35,030
There are also coral species

468
00:20:35,030 --> 00:20:37,220
that are more tolerant to stress.

469
00:20:37,220 --> 00:20:39,780
There's about 800 or so coral species.

470
00:20:39,780 --> 00:20:42,210
And we're starting to learn
with molecular techniques

471
00:20:42,210 --> 00:20:44,980
that there's probably way more than that.

472
00:20:44,980 --> 00:20:46,160
And each of those species

473
00:20:46,160 --> 00:20:48,060
has slightly different thermal threshold.

474
00:20:48,060 --> 00:20:50,620
So sometimes, you might see a picture

475
00:20:50,620 --> 00:20:51,900
from a bleached reef where you have

476
00:20:51,900 --> 00:20:55,790
one coral next to another and
one coral is perfectly fine

477
00:20:55,790 --> 00:20:58,340
and the other one is very,
very visibly bleached.

478
00:20:58,340 --> 00:21:01,460
And so trying to understand
what those differences are

479
00:21:01,460 --> 00:21:03,680
can offer some hope and also knowing

480
00:21:03,680 --> 00:21:06,080
that those differences
exist is a good sign

481
00:21:06,080 --> 00:21:08,300
for the potential corals to adapt

482
00:21:08,300 --> 00:21:09,750
to the future climate change.

483
00:21:11,440 --> 00:21:15,030
Then there are also reefs
that are already quite hot

484
00:21:15,030 --> 00:21:17,830
or that already have low
pH or sometimes both,

485
00:21:17,830 --> 00:21:19,640
but somehow they happen to have

486
00:21:19,640 --> 00:21:21,210
really healthy coral communities.

487
00:21:21,210 --> 00:21:22,043
I'm gonna talk to you

488
00:21:22,043 --> 00:21:24,060
about one of those in just a minute.

489
00:21:24,060 --> 00:21:26,730
And then there are other
reefs that might be affected

490
00:21:26,730 --> 00:21:28,990
and perhaps they bleach widely,

491
00:21:28,990 --> 00:21:31,080
but somehow recover very quickly.

492
00:21:31,080 --> 00:21:34,263
And I'll also talk to you about
what are those in a minute.

493
00:21:36,210 --> 00:21:37,510
So first, I'd like to talk to you

494
00:21:37,510 --> 00:21:39,950
about areas where reefs already

495
00:21:39,950 --> 00:21:44,360
in really kind of unideal conditions,

496
00:21:44,360 --> 00:21:45,987
but have very healthy environments.

497
00:21:45,987 --> 00:21:47,650
And so one of those examples

498
00:21:47,650 --> 00:21:50,920
is in the island archipelago of Palau,

499
00:21:50,920 --> 00:21:52,510
which is in the Western Pacific.

500
00:21:52,510 --> 00:21:54,160
It's a little bit too small to see it here

501
00:21:54,160 --> 00:21:55,570
zoomed out at the scale,

502
00:21:55,570 --> 00:21:57,080
but it's just east of the Philippines

503
00:21:57,080 --> 00:21:58,580
and north of Papua New Guinea.

504
00:21:59,520 --> 00:22:01,720
Now, what's really unique
about Palau is that A,

505
00:22:01,720 --> 00:22:04,050
it has a very extensive reef environment.

506
00:22:04,050 --> 00:22:06,880
So this is an outline of those reefs,

507
00:22:06,880 --> 00:22:08,390
all the things that you see here

508
00:22:08,390 --> 00:22:11,130
in this sort of dark blue grayish color

509
00:22:11,130 --> 00:22:12,720
are the outer barrier reefs.

510
00:22:12,720 --> 00:22:15,070
So it has this very nicely formed

511
00:22:15,070 --> 00:22:17,430
sort of atoll barrier reef structure.

512
00:22:17,430 --> 00:22:19,570
And then in addition, all of these islands

513
00:22:19,570 --> 00:22:23,730
here on the bottom have
this like very intricate

514
00:22:23,730 --> 00:22:27,750
network of bays and
little channels and inlets

515
00:22:27,750 --> 00:22:31,033
where there are reefs
and coral reefs in there.

516
00:22:31,890 --> 00:22:33,500
Now, one of the really fascinating things

517
00:22:33,500 --> 00:22:37,210
is that the environmental
conditions on the outer reefs

518
00:22:37,210 --> 00:22:39,240
are what we would expect
for the open ocean.

519
00:22:39,240 --> 00:22:42,653
It has still relatively basic pHs,

520
00:22:43,870 --> 00:22:45,720
has slightly cooler temperatures,

521
00:22:45,720 --> 00:22:49,200
but as you move into these
rock island environments,

522
00:22:49,200 --> 00:22:51,500
what we see is a pretty substantial

523
00:22:51,500 --> 00:22:53,110
increase in both temperature,

524
00:22:53,110 --> 00:22:55,780
sometimes as much as one
or two degrees Celsius,

525
00:22:55,780 --> 00:22:59,130
which is plenty of a
temperature difference

526
00:22:59,130 --> 00:23:01,273
to cause bleaching in many coral species.

527
00:23:02,180 --> 00:23:04,810
And in addition to the
increase in temperature,

528
00:23:04,810 --> 00:23:06,830
we see a decrease in pH.

529
00:23:06,830 --> 00:23:08,090
Now I'll remind you that pH

530
00:23:08,090 --> 00:23:09,770
is measured on a logarithmic scale,

531
00:23:09,770 --> 00:23:13,900
so this difference is
actually quite severe.

532
00:23:13,900 --> 00:23:17,730
Now, this picture here was
taken in the rock islands,

533
00:23:17,730 --> 00:23:21,270
and as you can see, the
coral there look beautiful,

534
00:23:21,270 --> 00:23:22,790
they're colorful, they're happy.

535
00:23:22,790 --> 00:23:26,350
It's actually really densely
populated with corals.

536
00:23:26,350 --> 00:23:28,790
And so in Palau, these
rock island environments

537
00:23:28,790 --> 00:23:30,760
are actually healthier
by some of the metrics

538
00:23:30,760 --> 00:23:32,870
that we often use to
measure coral reef health

539
00:23:32,870 --> 00:23:34,770
and some of the outer reef environments,

540
00:23:34,770 --> 00:23:37,470
which in theory, have better
environmental conditions.

541
00:23:40,120 --> 00:23:41,120
So here, on the top left,

542
00:23:41,120 --> 00:23:44,350
I'm showing you a graph
that measures coral cover,

543
00:23:44,350 --> 00:23:47,100
which is essentially if you
were to take a square meter

544
00:23:47,100 --> 00:23:49,740
and plop it down on the reef bottom,

545
00:23:49,740 --> 00:23:52,352
how much of that square
meter is covered in coral,

546
00:23:52,352 --> 00:23:54,750
coral that's alive.

547
00:23:54,750 --> 00:23:57,370
And on the x-axis here
is aragonite saturation,

548
00:23:57,370 --> 00:24:00,100
which is a measure meant
that's very related to pH,

549
00:24:00,100 --> 00:24:03,370
so the lower the aragonite
saturation, the lower the pH.

550
00:24:03,370 --> 00:24:06,540
And as you go into these low
pH rock island environments,

551
00:24:06,540 --> 00:24:09,300
what we actually see is an
increase in coral cover.

552
00:24:09,300 --> 00:24:11,570
So there's actually more coral

553
00:24:11,570 --> 00:24:14,453
living in these rock island
environments per square area

554
00:24:14,453 --> 00:24:17,183
than in some of these outer reef habitats.

555
00:24:18,060 --> 00:24:21,810
Likewise, when there are
bleaching events in Palau,

556
00:24:21,810 --> 00:24:23,700
corals that live on the outer reefs,

557
00:24:23,700 --> 00:24:24,800
which is shown here in blue,

558
00:24:24,800 --> 00:24:26,970
have a higher percentage of bleaching.

559
00:24:26,970 --> 00:24:30,690
So in the sites that are on
those outer barrier regions,

560
00:24:30,690 --> 00:24:33,130
sometimes we see as much as 60% bleaching,

561
00:24:33,130 --> 00:24:34,670
whereas the rock island environments

562
00:24:34,670 --> 00:24:37,620
have much lower bleaching overall.

563
00:24:37,620 --> 00:24:40,950
So this has presented a really
interesting kind of paradox

564
00:24:40,950 --> 00:24:43,150
where these environments
that one would think

565
00:24:43,150 --> 00:24:45,480
should be really stressful to the corals

566
00:24:46,330 --> 00:24:49,600
seems to have bred very tolerant corals.

567
00:24:49,600 --> 00:24:50,960
And so this is actually
one of the questions

568
00:24:50,960 --> 00:24:53,690
that I set out to answer in my PhD,

569
00:24:53,690 --> 00:24:55,680
and it's something that
I'm still working on

570
00:24:55,680 --> 00:24:57,083
several years later.

571
00:24:57,990 --> 00:25:00,080
So one of the things that
I've done on this front

572
00:25:00,080 --> 00:25:02,120
is to use genetic analysis to look

573
00:25:02,120 --> 00:25:05,570
at how these populations
differ from each other.

574
00:25:05,570 --> 00:25:09,460
And I've focused in on
a coral called Porites,

575
00:25:09,460 --> 00:25:11,910
which grows in this massive form here.

576
00:25:11,910 --> 00:25:14,370
They can grow as big as like a small car.

577
00:25:14,370 --> 00:25:17,180
And their growth form
is actually very helpful

578
00:25:17,180 --> 00:25:20,280
for a reason that I'll
mention in just a minute.

579
00:25:20,280 --> 00:25:23,150
But across several years,
I've been lucky enough

580
00:25:23,150 --> 00:25:26,840
to go to Palau and sample
several hundred of these colonies

581
00:25:26,840 --> 00:25:28,600
and extract DNA from them and then look

582
00:25:28,600 --> 00:25:31,910
at what genetic differences
might be going on

583
00:25:31,910 --> 00:25:34,367
between the ones that live
in these hot environments

584
00:25:34,367 --> 00:25:37,150
and the ones that are found outside.

585
00:25:37,150 --> 00:25:38,780
So I've sampled several hundred of these.

586
00:25:38,780 --> 00:25:42,420
And then to give you the
kind of biggest picture,

587
00:25:42,420 --> 00:25:44,520
what I'll show you next is a breakdown

588
00:25:44,520 --> 00:25:47,910
of genetic kind of subpopulations.

589
00:25:47,910 --> 00:25:50,980
So the different colors in the
chart that I'm about to show

590
00:25:50,980 --> 00:25:54,570
represent populations
that have been somewhat

591
00:25:55,430 --> 00:25:57,010
genetically distinct from each other

592
00:25:57,010 --> 00:25:58,253
for some amount of time.

593
00:25:59,940 --> 00:26:03,750
Now, what we see is that on
the cooler high pH reefs,

594
00:26:03,750 --> 00:26:05,350
so these are those outer reef environments

595
00:26:05,350 --> 00:26:07,630
that are shown here in
this square on the left,

596
00:26:07,630 --> 00:26:10,090
there's a predominance of
a particular population

597
00:26:10,090 --> 00:26:13,230
that I've colored here in dark blue.

598
00:26:13,230 --> 00:26:15,780
Whereas when we move into
the hotter lower pH reefs

599
00:26:15,780 --> 00:26:17,610
inside those rock island networks,

600
00:26:17,610 --> 00:26:19,230
we see almost a complete shift

601
00:26:19,230 --> 00:26:22,770
in the population structure
of these environments.

602
00:26:22,770 --> 00:26:25,810
We see that the reefs are now overtaken

603
00:26:25,810 --> 00:26:27,600
mostly by this light blue population.

604
00:26:27,600 --> 00:26:30,090
And in some other cases,
this red population

605
00:26:30,090 --> 00:26:32,210
that's actually almost completely absent

606
00:26:32,210 --> 00:26:33,860
from the outer reef environments.

607
00:26:34,700 --> 00:26:37,330
And so this is an initial
kind of finding that suggests

608
00:26:37,330 --> 00:26:39,350
that there's some genetic differentiation

609
00:26:39,350 --> 00:26:42,620
that's occurring across
this environmental gradient.

610
00:26:42,620 --> 00:26:44,420
Now, another question that I asked was,

611
00:26:44,420 --> 00:26:47,700
does this genetic differentiation
map to differences

612
00:26:47,700 --> 00:26:49,700
that we might find in thermal tolerance?

613
00:26:50,610 --> 00:26:52,700
Now, one of the neat things about Porites

614
00:26:52,700 --> 00:26:57,583
is that because it grows
in this massive morphology,

615
00:27:00,300 --> 00:27:01,500
we have a way of essentially

616
00:27:01,500 --> 00:27:03,943
looking back into its past growth history.

617
00:27:04,850 --> 00:27:07,810
And we do that by taking a coral core.

618
00:27:07,810 --> 00:27:09,360
So you can dive down with a drill

619
00:27:09,360 --> 00:27:11,050
and drill into the coral colony.

620
00:27:11,050 --> 00:27:13,910
And I promise you that this
does not kill the coral.

621
00:27:13,910 --> 00:27:16,010
You can like patch the
little hole that you made

622
00:27:16,010 --> 00:27:18,840
and then it continues growing
through the rest of it.

623
00:27:18,840 --> 00:27:20,220
The live part of the coral is actually

624
00:27:20,220 --> 00:27:22,560
only in the upper like centimeter or two.

625
00:27:22,560 --> 00:27:25,240
So the rest of it is just
dead, not dead skeleton,

626
00:27:25,240 --> 00:27:28,020
but previous skeleton
that it has deposited.

627
00:27:28,020 --> 00:27:31,020
There's certainly other
critters that live in there now.

628
00:27:31,020 --> 00:27:35,380
And so you end up with the
skeletal biopsy, if you will,

629
00:27:35,380 --> 00:27:37,230
the cylinder that then you can scan

630
00:27:37,230 --> 00:27:39,980
and see how the coral has
grown throughout time.

631
00:27:39,980 --> 00:27:42,150
Now, similar to tree rings,

632
00:27:42,150 --> 00:27:44,600
corals lay down their
skeleton in a particular way,

633
00:27:44,600 --> 00:27:48,020
so you can count back
and figure out, in 2010,

634
00:27:48,020 --> 00:27:50,140
for instance, when there was
a warming event in Palau,

635
00:27:50,140 --> 00:27:51,880
what was happening.

636
00:27:51,880 --> 00:27:54,000
And so what we found when we looked

637
00:27:54,000 --> 00:27:58,510
at a number of different
coral cores across the Pacific

638
00:27:58,510 --> 00:28:01,010
is that when there are
events of high temperature,

639
00:28:01,920 --> 00:28:03,770
and therefore the coral is bleaching,

640
00:28:03,770 --> 00:28:05,880
it leaves a scar in the skeleton.

641
00:28:05,880 --> 00:28:07,040
It leaves a signature behind

642
00:28:07,040 --> 00:28:09,100
that we can measure and quantify.

643
00:28:09,100 --> 00:28:11,500
And that's something that I'm
showing you here in the right,

644
00:28:11,500 --> 00:28:14,270
this bright white band is a time

645
00:28:14,270 --> 00:28:16,760
when the coral was actually bleached.

646
00:28:16,760 --> 00:28:19,610
And the reason that it's white

647
00:28:19,610 --> 00:28:21,370
is that it's a very densely packed

648
00:28:21,370 --> 00:28:24,120
piece of aragonite skeleton.

649
00:28:24,120 --> 00:28:25,770
And what we think is happening

650
00:28:25,770 --> 00:28:26,877
is that because the coral is bleached

651
00:28:26,877 --> 00:28:30,300
and it's not really in a very
energetically favorable state,

652
00:28:30,300 --> 00:28:31,720
it's not growing upwards.

653
00:28:31,720 --> 00:28:34,100
So the little aragonite
that it's depositing

654
00:28:34,100 --> 00:28:37,350
is just being compacted in that row

655
00:28:37,350 --> 00:28:39,600
and it leaves behind
this really bright band.

656
00:28:40,780 --> 00:28:42,920
Now, what that allows us
to do is look back in time

657
00:28:42,920 --> 00:28:47,060
and count how many of these
corals had stress bands

658
00:28:47,060 --> 00:28:49,770
and then relate that to
the genetic signatures

659
00:28:49,770 --> 00:28:51,920
that we're seeing across
these populations.

660
00:28:54,830 --> 00:28:58,100
So I'll just show you one very small

661
00:28:58,100 --> 00:29:00,950
data point from this analysis,

662
00:29:00,950 --> 00:29:02,310
where we looked at stress band

663
00:29:02,310 --> 00:29:05,260
of individual colonies in 1998.

664
00:29:05,260 --> 00:29:06,330
So we looked at that core

665
00:29:06,330 --> 00:29:09,320
back to when it would
have corresponded to 1998

666
00:29:09,320 --> 00:29:12,840
and figured out which ones had
stress bands in their cores

667
00:29:12,840 --> 00:29:15,960
and then related that to
their genetic population.

668
00:29:15,960 --> 00:29:17,120
Now, what you might notice

669
00:29:17,120 --> 00:29:18,730
is that that dark blue population,

670
00:29:18,730 --> 00:29:21,950
which is shown here in this
first graph, first bar,

671
00:29:21,950 --> 00:29:24,850
the one that's most common in
those outer reef environments

672
00:29:24,850 --> 00:29:27,460
has the highest proportion
of stress bands.

673
00:29:27,460 --> 00:29:29,580
So those corals are highly susceptible

674
00:29:29,580 --> 00:29:31,683
to the warming that occurred in 1998.

675
00:29:32,530 --> 00:29:34,230
Now, the corals that mostly live

676
00:29:34,230 --> 00:29:36,520
inside those rock island environments,

677
00:29:36,520 --> 00:29:40,004
which by the way, still get hotter still

678
00:29:40,004 --> 00:29:42,650
in 1998, when there's a bleaching event,

679
00:29:42,650 --> 00:29:45,650
actually showed a very low
percentage of stress bands.

680
00:29:45,650 --> 00:29:49,400
So even though they're in
warmer environments overall,

681
00:29:49,400 --> 00:29:51,550
these environments get hotter still

682
00:29:51,550 --> 00:29:54,240
when there's a bleaching,
when there's a warming event,

683
00:29:54,240 --> 00:29:56,300
most of them are not bleaching.

684
00:29:56,300 --> 00:29:59,640
And so what this hints at is that Palau

685
00:29:59,640 --> 00:30:02,230
is likely home to corals
that have a genetic basis

686
00:30:02,230 --> 00:30:03,710
for higher thermal tolerance.

687
00:30:03,710 --> 00:30:05,760
And so a lot of the followup
work that I've done since

688
00:30:05,760 --> 00:30:07,660
has been trying to get at this question

689
00:30:07,660 --> 00:30:10,160
and try to understand the nuances

690
00:30:10,160 --> 00:30:12,490
in the system a little bit more clearly.

691
00:30:12,490 --> 00:30:13,590
So if you have questions about that,

692
00:30:13,590 --> 00:30:15,893
please feel free to ask me in the Q and A.

693
00:30:15,893 --> 00:30:19,290
I just didn't wanna throw
too much data at you.

694
00:30:19,290 --> 00:30:21,680
All right, so now I'd like to take you

695
00:30:21,680 --> 00:30:24,250
to a different system.

696
00:30:24,250 --> 00:30:25,363
Now, this is Jarvis Island.

697
00:30:25,363 --> 00:30:27,860
It's a US territory that you
might not have ever heard of,

698
00:30:27,860 --> 00:30:30,760
but it's actually located in
the center of the Pacific,

699
00:30:30,760 --> 00:30:33,390
pretty much on the
equator, about as far away

700
00:30:33,390 --> 00:30:35,440
from any continental mass as you can get.

701
00:30:36,540 --> 00:30:39,940
And this color scheme that
you're seeing on the map here

702
00:30:39,940 --> 00:30:42,120
is representing the temperature anomaly.

703
00:30:42,120 --> 00:30:46,900
So how much hotter than
normal the waters were in 2015

704
00:30:46,900 --> 00:30:50,730
when there was that massive
global bleaching event.

705
00:30:50,730 --> 00:30:52,410
Now, you'll notice that Jarvis

706
00:30:52,410 --> 00:30:56,023
is in pretty much the
hottest spot of this map.

707
00:30:57,640 --> 00:30:59,060
Now, under normal circumstances,

708
00:30:59,060 --> 00:31:00,540
Jarvis is a really healthy,

709
00:31:00,540 --> 00:31:02,453
really beautiful coral ecosystem.

710
00:31:04,790 --> 00:31:05,700
It's even been rated

711
00:31:05,700 --> 00:31:08,240
one of the healthiest coral environments

712
00:31:09,390 --> 00:31:12,313
in the world on multiple occasions, sorry.

713
00:31:13,260 --> 00:31:17,310
But it's located in a region
that sees frequent warming,

714
00:31:17,310 --> 00:31:18,230
due to what are known

715
00:31:18,230 --> 00:31:20,720
as El Nino-Southern Oscillation events,

716
00:31:20,720 --> 00:31:23,760
which are climate oscillations
that cause warming

717
00:31:23,760 --> 00:31:25,737
particularly in the
Central Pacific region,

718
00:31:25,737 --> 00:31:27,587
but they also have effects worldwide.

719
00:31:28,560 --> 00:31:31,640
Now, in 2014 to 2016 when we visited

720
00:31:31,640 --> 00:31:33,130
this site multiple times,

721
00:31:33,130 --> 00:31:35,530
we saw almost 100% bleaching.

722
00:31:35,530 --> 00:31:36,930
So pretty much every single coral

723
00:31:36,930 --> 00:31:39,960
that was on that island was bleached.

724
00:31:39,960 --> 00:31:43,200
And when we returned a year later in 2016,

725
00:31:43,200 --> 00:31:45,690
almost 90% of them had died,

726
00:31:45,690 --> 00:31:48,010
or at least we thought they had.

727
00:31:48,010 --> 00:31:51,280
Some of my colleagues
returned yet again in 2017,

728
00:31:51,280 --> 00:31:54,510
and what they found was a
really surprising recovery.

729
00:31:54,510 --> 00:31:58,250
So this is a colony, again,
that same massive Porites.

730
00:31:58,250 --> 00:32:00,740
In 2016, you can see that it looks like

731
00:32:00,740 --> 00:32:02,580
there's absolutely no live coral tissue

732
00:32:02,580 --> 00:32:04,480
anywhere on this piece of rock.

733
00:32:04,480 --> 00:32:09,230
It's kind of all been overgrown
by this red fuzzy algae.

734
00:32:09,230 --> 00:32:10,510
And this is 2016.

735
00:32:10,510 --> 00:32:12,570
You'll notice there that my colleagues

736
00:32:12,570 --> 00:32:13,770
are taking a core of it.

737
00:32:14,650 --> 00:32:17,330
Now, in 2017, when they returned,

738
00:32:17,330 --> 00:32:19,370
this looks like a pretty
healthy, happy colony.

739
00:32:19,370 --> 00:32:22,920
Most of this tissue, and
this is not a small colony,

740
00:32:22,920 --> 00:32:27,920
here's a scuba tank for
scale, has recovered.

741
00:32:28,020 --> 00:32:29,970
Most of this tissue is alive and healthy.

742
00:32:29,970 --> 00:32:31,000
Here's a closeup.

743
00:32:31,000 --> 00:32:33,400
This is all happy coral tissue.

744
00:32:33,400 --> 00:32:35,450
And if you're not convinced
that this is the same colony,

745
00:32:35,450 --> 00:32:39,650
I'll guide you through this
kind of very unique pattern here

746
00:32:39,650 --> 00:32:44,090
that we see in the skeleton,
and we see it here too.

747
00:32:44,090 --> 00:32:45,860
So this particular colony was able

748
00:32:45,860 --> 00:32:50,090
to get really impacted
by this bleaching event,

749
00:32:50,090 --> 00:32:52,250
presumably almost entirely die,

750
00:32:52,250 --> 00:32:54,990
yet, within a year, it had recovered

751
00:32:54,990 --> 00:32:58,010
most of its tissue and
most of its symbionts.

752
00:32:58,010 --> 00:33:02,180
Now, when we've cored
colonies from this area,

753
00:33:02,180 --> 00:33:05,330
what we find is really interesting.

754
00:33:05,330 --> 00:33:09,133
So here's a long core from
another colony at Jarvis.

755
00:33:10,010 --> 00:33:11,820
And you'll notice that it's,

756
00:33:11,820 --> 00:33:14,340
in this case, it's going
back to about 1980,

757
00:33:14,340 --> 00:33:15,720
and you'll notice that there were multiple

758
00:33:15,720 --> 00:33:18,610
stress bands in this individual colony.

759
00:33:18,610 --> 00:33:22,190
So every time that there's
a really big bleaching event

760
00:33:22,190 --> 00:33:25,100
or a very, very hot temperature anomaly,

761
00:33:25,100 --> 00:33:26,970
this colony is bleaching, right?

762
00:33:26,970 --> 00:33:28,500
It does so during the first

763
00:33:28,500 --> 00:33:30,710
massive bleaching event in '82, '83,

764
00:33:30,710 --> 00:33:32,710
it does so again a few years later,

765
00:33:32,710 --> 00:33:34,760
and then again, and then
again, and then again,

766
00:33:34,760 --> 00:33:37,000
and then again, and then again.

767
00:33:37,000 --> 00:33:40,060
But it's able to continue
growing and surviving.

768
00:33:40,060 --> 00:33:42,060
This is again the same individual colony.

769
00:33:42,060 --> 00:33:44,433
It has not died during these times.

770
00:33:46,200 --> 00:33:47,410
And so we see this pattern,

771
00:33:47,410 --> 00:33:50,550
actually multiple of the
cores from this island.

772
00:33:50,550 --> 00:33:52,750
And in one case where we
have the longest core,

773
00:33:52,750 --> 00:33:53,860
we actually see stress bands

774
00:33:53,860 --> 00:33:56,270
that date back to as old as 1920.

775
00:33:56,270 --> 00:33:57,730
So it seems like in this region,

776
00:33:57,730 --> 00:34:00,100
bleaching has been occurring
way before scientists

777
00:34:00,100 --> 00:34:01,950
even knew that bleaching was a thing.

778
00:34:01,950 --> 00:34:04,130
And that the colonies in this area

779
00:34:04,130 --> 00:34:07,370
are capable of bouncing
back from it very quickly,

780
00:34:07,370 --> 00:34:08,670
even if they are affected.

781
00:34:12,220 --> 00:34:15,090
So today, I've shown you two examples

782
00:34:15,090 --> 00:34:17,760
of what are called coral reef refugia,

783
00:34:17,760 --> 00:34:20,330
which are places where
corals might have a chance

784
00:34:20,330 --> 00:34:21,780
to really live a little bit longer

785
00:34:21,780 --> 00:34:24,010
than we project for many areas.

786
00:34:24,010 --> 00:34:25,500
Japan, as I alluded to briefly,

787
00:34:25,500 --> 00:34:26,660
might be another example of that

788
00:34:26,660 --> 00:34:27,920
where we're seeing range expansion

789
00:34:27,920 --> 00:34:29,913
of corals into cooler waters.

790
00:34:31,630 --> 00:34:35,140
So all of these examples
provide some hope for the future

791
00:34:35,140 --> 00:34:37,630
that corals might be able to persist,

792
00:34:37,630 --> 00:34:40,130
even in light of a lot of these

793
00:34:40,130 --> 00:34:42,480
very heavy stressors that
they're experiencing.

794
00:34:43,640 --> 00:34:45,100
So what other things are being done?

795
00:34:45,100 --> 00:34:48,020
And how else can we
look towards the future

796
00:34:48,020 --> 00:34:49,370
of coral reef environments?

797
00:34:52,130 --> 00:34:55,225
So one thing that's happening

798
00:34:55,225 --> 00:34:57,620
and increasing throughout the world

799
00:34:57,620 --> 00:35:00,880
are large-scale restoration
and captive breeding efforts.

800
00:35:00,880 --> 00:35:02,430
A lot of this work is currently focused

801
00:35:02,430 --> 00:35:03,790
in Florida and in the Caribbean

802
00:35:03,790 --> 00:35:06,780
where coral disease is a
very big stressor as well.

803
00:35:06,780 --> 00:35:10,280
So people have started
focusing on trying to breed

804
00:35:10,280 --> 00:35:13,370
disease resilient corals
and outplant corals

805
00:35:13,370 --> 00:35:14,920
of species that have suffered

806
00:35:14,920 --> 00:35:18,230
really big losses in the
Caribbean, such as acroporas.

807
00:35:18,230 --> 00:35:22,000
There's also a lot of research
that's trying to evolve

808
00:35:22,000 --> 00:35:24,960
more thermally tolerant
symbionts in the lab.

809
00:35:24,960 --> 00:35:26,510
So one of the things that
I kind of glossed over

810
00:35:26,510 --> 00:35:29,343
is that there's several
different species of symbionts.

811
00:35:29,343 --> 00:35:30,990
There's almost hundreds of different

812
00:35:30,990 --> 00:35:34,040
species of symbionts that
associate with corals.

813
00:35:34,040 --> 00:35:36,280
And each of those symbiont species

814
00:35:36,280 --> 00:35:38,980
has slightly different
thermal sensitivities.

815
00:35:38,980 --> 00:35:41,270
Some of them can tolerate
much higher temperatures

816
00:35:41,270 --> 00:35:44,830
before they break down
and lead to bleaching.

817
00:35:44,830 --> 00:35:46,180
And so there's a lot of work

818
00:35:46,180 --> 00:35:48,200
that's trying to understand
why that's the case,

819
00:35:48,200 --> 00:35:50,780
as well as evolve in the lab,

820
00:35:50,780 --> 00:35:52,000
symbionts that are perhaps

821
00:35:52,000 --> 00:35:53,070
a little bit more thermally tolerant,

822
00:35:53,070 --> 00:35:55,750
and then try to use
those to reinfect corals

823
00:35:55,750 --> 00:35:57,700
with more thermally tolerant symbionts.

824
00:35:58,620 --> 00:36:00,280
There are also assisted evolution

825
00:36:00,280 --> 00:36:01,750
efforts of corals themselves,

826
00:36:01,750 --> 00:36:03,430
both in the field and in the lab.

827
00:36:03,430 --> 00:36:06,583
So taking corals that are either,

828
00:36:08,080 --> 00:36:10,300
you either subject them
to heat stress in the lab

829
00:36:10,300 --> 00:36:13,410
and then take the ones that
are most strong against that

830
00:36:13,410 --> 00:36:14,910
and then try to breed
those with each other.

831
00:36:14,910 --> 00:36:17,290
Or in the field, you take
survivors from bleaching events

832
00:36:17,290 --> 00:36:21,173
and then try to use your
selection pressure that way.

833
00:36:22,930 --> 00:36:25,410
Then there's a lot of
work that's being done

834
00:36:25,410 --> 00:36:27,060
and that I'm quite interested in

835
00:36:27,060 --> 00:36:28,240
in trying to really understand

836
00:36:28,240 --> 00:36:30,040
what genes are controlling
thermal tolerance

837
00:36:30,040 --> 00:36:33,130
and how we can use that
information to identify

838
00:36:33,130 --> 00:36:36,380
corals and species and
locations that might have corals

839
00:36:36,380 --> 00:36:38,683
with higher thermal tolerance than others.

840
00:36:40,090 --> 00:36:41,960
And then there's also a lot of work going

841
00:36:41,960 --> 00:36:43,610
into identifying other resilient reefs.

842
00:36:43,610 --> 00:36:46,400
So I've shown you two or three
examples of resilient reefs.

843
00:36:46,400 --> 00:36:49,070
There are a few others,
but there's a lot of effort

844
00:36:49,070 --> 00:36:51,000
in trying to find more of these examples

845
00:36:51,000 --> 00:36:53,390
and trying to protect
them so that the few reefs

846
00:36:53,390 --> 00:36:56,420
that we have that are
stronger than most of them

847
00:36:56,420 --> 00:37:00,040
don't also get bombarded
by additional stressors

848
00:37:00,040 --> 00:37:01,600
such as runoff or coastal development

849
00:37:01,600 --> 00:37:03,050
or other things of that sort.

850
00:37:04,710 --> 00:37:07,530
Okay, now that being said, refugia,

851
00:37:07,530 --> 00:37:08,770
even though they're very important

852
00:37:08,770 --> 00:37:11,830
and they offer us some help,
they're not invincible.

853
00:37:11,830 --> 00:37:15,440
So Jarvis Island, yes, it
can recover quite quickly,

854
00:37:15,440 --> 00:37:20,440
but it still had 90% coral
mortality during that year.

855
00:37:20,440 --> 00:37:22,870
So it's gonna take a
long time for that reef

856
00:37:22,870 --> 00:37:27,070
to really regain the
same kind of coral cover

857
00:37:27,070 --> 00:37:29,200
that it had prior to that event.

858
00:37:29,200 --> 00:37:31,520
And if these bleaching events
are getting more severe

859
00:37:31,520 --> 00:37:34,190
and they're coming in shorter
and shorter intervals,

860
00:37:34,190 --> 00:37:35,470
they're becoming more frequent,

861
00:37:35,470 --> 00:37:37,190
it's gonna be way harder for Jarvis

862
00:37:37,190 --> 00:37:40,630
to continue to keep up
that level of resiliency.

863
00:37:40,630 --> 00:37:43,730
Likewise, in Japan,
because these environments

864
00:37:43,730 --> 00:37:45,810
are still not like highly
suitable for corals,

865
00:37:45,810 --> 00:37:49,410
when the temperatures go back
down to being slightly cooler,

866
00:37:49,410 --> 00:37:51,050
then that also impacts the corals.

867
00:37:51,050 --> 00:37:53,180
They bleach because the
temperature's too cold

868
00:37:53,180 --> 00:37:55,320
and then they die, and so it's still not,

869
00:37:55,320 --> 00:37:57,933
it's not a safe haven, let's say.

870
00:37:58,988 --> 00:38:01,170
And in Palau, even though the rock islands

871
00:38:01,170 --> 00:38:03,270
do have more thermally tolerant corals,

872
00:38:03,270 --> 00:38:04,720
they're not immune to bleaching, right?

873
00:38:04,720 --> 00:38:07,050
We still see some bleaching
in these environments.

874
00:38:07,050 --> 00:38:08,810
And as the temperature
gets hotter and hotter,

875
00:38:08,810 --> 00:38:12,830
we might start hitting
their higher thermal limits.

876
00:38:12,830 --> 00:38:15,280
So while refugia are important

877
00:38:15,280 --> 00:38:17,280
and while a lot of the
efforts that I just mentioned

878
00:38:17,280 --> 00:38:19,580
are incredibly important
and we need to do them,

879
00:38:19,580 --> 00:38:21,770
we also need to understand
that the root cause

880
00:38:21,770 --> 00:38:24,790
of all of this is really rising
greenhouse gas emissions.

881
00:38:24,790 --> 00:38:27,140
They're the main cause of
rising ocean temperatures

882
00:38:27,140 --> 00:38:28,940
and of rising air temperatures.

883
00:38:28,940 --> 00:38:31,940
And in order to actually fix the problem,

884
00:38:31,940 --> 00:38:34,340
These are all solutions,
these are all like medicines

885
00:38:34,340 --> 00:38:36,240
that help alleviate the symptoms,

886
00:38:36,240 --> 00:38:39,360
but you need to actually
treat the cause of the issue,

887
00:38:39,360 --> 00:38:41,320
which is rising greenhouse gas emissions

888
00:38:41,320 --> 00:38:43,490
in order to curtail some of the changes

889
00:38:43,490 --> 00:38:47,883
that are projected to
happen across the planet.

890
00:38:48,780 --> 00:38:51,560
And this here on the right
is just a graphic that shows

891
00:38:51,560 --> 00:38:53,790
how much of the heat
that we kind of produce

892
00:38:53,790 --> 00:38:55,320
through greenhouse gas emission

893
00:38:55,320 --> 00:38:57,250
has been absorbed by the ocean.

894
00:38:57,250 --> 00:38:59,020
And what you might
notice is that the ocean

895
00:38:59,020 --> 00:39:01,060
has done the bulk of the work

896
00:39:01,060 --> 00:39:03,160
in taking up all of the
heat that we've produced,

897
00:39:03,160 --> 00:39:04,860
which is part of the reason why corals

898
00:39:04,860 --> 00:39:08,290
are being some of the kind
of heralds of the future

899
00:39:08,290 --> 00:39:10,340
in regard to their climate change impacts.

900
00:39:10,340 --> 00:39:11,620
They're being impacted first

901
00:39:11,620 --> 00:39:13,720
because the oceans are warming so quickly.

902
00:39:16,100 --> 00:39:19,740
All right, and all of
this work is not just me.

903
00:39:19,740 --> 00:39:21,730
There's a lot of people involved.

904
00:39:21,730 --> 00:39:23,760
So I like to take a few moments

905
00:39:23,760 --> 00:39:26,060
just to acknowledge all of
my advisors and mentors,

906
00:39:26,060 --> 00:39:27,790
a lot of the co-authors and collaborators

907
00:39:27,790 --> 00:39:30,220
on the work that I presented today,

908
00:39:30,220 --> 00:39:33,370
as well as the field crews in the boats

909
00:39:33,370 --> 00:39:37,860
that I've worked on the
Republic of Kiribati and Palau,

910
00:39:37,860 --> 00:39:41,340
both of which are amazing
countries to visit

911
00:39:41,340 --> 00:39:43,530
and have incredible people.

912
00:39:43,530 --> 00:39:44,770
And then of course, all of the funding

913
00:39:44,770 --> 00:39:47,743
that went into making some
of this research possible.

914
00:39:49,310 --> 00:39:50,880
So I'll just give a quick summary

915
00:39:50,880 --> 00:39:53,010
of what I shared with you today.

916
00:39:53,010 --> 00:39:54,429
First, it's that coral reefs

917
00:39:54,429 --> 00:39:57,253
provide invaluable ecosystem services.

918
00:39:58,320 --> 00:40:01,140
Corals need stable ocean
conditions to live.

919
00:40:01,140 --> 00:40:04,560
They're kind of a little bit
of a Goldilocks organism.

920
00:40:04,560 --> 00:40:06,250
They need to be at like
just the right temperature

921
00:40:06,250 --> 00:40:08,250
at just the right pH
with just the right light

922
00:40:08,250 --> 00:40:10,230
in order to be really happy.

923
00:40:10,230 --> 00:40:11,820
And a lot of the things
that humans are doing

924
00:40:11,820 --> 00:40:13,710
are changing all of those parameters,

925
00:40:13,710 --> 00:40:15,710
so they're really struggling to keep up.

926
00:40:17,000 --> 00:40:19,160
High temperatures in
particular trigger bleaching

927
00:40:19,160 --> 00:40:22,490
and can kill corals on a
massive worldwide scale.

928
00:40:22,490 --> 00:40:23,810
Lower pH is making it harder

929
00:40:23,810 --> 00:40:25,963
for corals to grow across the planet.

930
00:40:27,090 --> 00:40:29,300
And scientists are desperately
trying to understand

931
00:40:29,300 --> 00:40:31,870
why and how some corals or some reefs

932
00:40:31,870 --> 00:40:33,450
are stronger than others.

933
00:40:33,450 --> 00:40:34,610
But at the end of the day, really,

934
00:40:34,610 --> 00:40:36,860
we need collective climate action

935
00:40:36,860 --> 00:40:39,600
in order to advance both ocean

936
00:40:39,600 --> 00:40:41,870
and human health and prosperity.

937
00:40:41,870 --> 00:40:44,453
So with that, I will take questions.

938
00:40:47,770 --> 00:40:49,640
- Dr. Rivera, this is Nelson Scottgale.

939
00:40:49,640 --> 00:40:52,080
Thank you so much for a wonderful talk.

940
00:40:52,080 --> 00:40:53,400
- Thank you.
- We really appreciate it.

941
00:40:53,400 --> 00:40:57,310
And we do have many questions here.

942
00:40:57,310 --> 00:40:59,530
And so the first one we got was,

943
00:40:59,530 --> 00:41:00,780
can bleaching also happen

944
00:41:00,780 --> 00:41:03,740
due to a change in the pH of the water?

945
00:41:03,740 --> 00:41:05,410
- Yeah, so sometimes you can see

946
00:41:05,410 --> 00:41:07,300
bleaching induced by pH changes.

947
00:41:07,300 --> 00:41:08,700
Usually the pH change would need

948
00:41:08,700 --> 00:41:11,223
to be very extreme for that to happen.

949
00:41:12,370 --> 00:41:15,670
But bleaching overall
is kind of a breakdown

950
00:41:15,670 --> 00:41:17,190
in the symbiosis of the coral.

951
00:41:17,190 --> 00:41:20,160
And there's a lot of things
that make that symbiosis stable.

952
00:41:20,160 --> 00:41:21,810
So temperature is the main one

953
00:41:21,810 --> 00:41:23,900
that has the kind of fastest effect.

954
00:41:23,900 --> 00:41:26,350
One of the other ones that
can also lead to bleaching

955
00:41:26,350 --> 00:41:30,150
quite quickly is changes
in nitrogen availability.

956
00:41:30,150 --> 00:41:33,540
So the coral is actually trying to

957
00:41:33,540 --> 00:41:35,400
kind of keep the
symbionts in check, right?

958
00:41:35,400 --> 00:41:37,100
It needs to do this delicate dance

959
00:41:37,100 --> 00:41:39,810
where it wants to have enough
symbionts in its tissues

960
00:41:39,810 --> 00:41:41,980
to provide it with the
nutrition that it needs,

961
00:41:41,980 --> 00:41:43,920
but it can't really
like over-fertilize them

962
00:41:43,920 --> 00:41:47,200
or they grow so fast that
it kind of hurts the coral.

963
00:41:47,200 --> 00:41:49,960
And so for instance, in the
case of agricultural runoff,

964
00:41:49,960 --> 00:41:51,910
which is very nitrogen replete,

965
00:41:51,910 --> 00:41:54,310
that can often trigger
coral bleaching as well.

966
00:41:54,310 --> 00:41:57,710
Because now, the coral
can no longer like control

967
00:41:57,710 --> 00:41:59,240
how much fertilizer it's giving the coral.

968
00:41:59,240 --> 00:42:00,890
It's getting all this extra fertilization

969
00:42:00,890 --> 00:42:04,347
and the symbionts start
growing and overtake things

970
00:42:04,347 --> 00:42:05,220
and then the coral freaks out

971
00:42:05,220 --> 00:42:07,530
and throws them all out and bleaches.

972
00:42:07,530 --> 00:42:10,030
With pH, it's a little bit more nuanced.

973
00:42:10,030 --> 00:42:13,410
So for instance, with pH,
there's often increasing CO2,

974
00:42:13,410 --> 00:42:15,780
which can like simulate photosynthesis,

975
00:42:15,780 --> 00:42:18,060
and so the symbiont is
happy for a little bit,

976
00:42:18,060 --> 00:42:19,390
but then if it like, again,

977
00:42:19,390 --> 00:42:21,900
kind of gets over-fertilized
and then grows too much, then,

978
00:42:21,900 --> 00:42:24,750
again, the bleaching can kind
of occur because of that.

979
00:42:24,750 --> 00:42:27,810
But it usually needs to be like
very low pH, very high pCO2

980
00:42:27,810 --> 00:42:30,310
for that to actually trigger
bleaching on its own.

981
00:42:32,660 --> 00:42:35,130
- Thanks for a wonderful
presentation, Dr. Rivera.

982
00:42:35,130 --> 00:42:36,070
This is Ryan Fisher

983
00:42:36,070 --> 00:42:38,833
with the next question from our audience.

984
00:42:39,810 --> 00:42:41,380
And it's sort of a two-part question.

985
00:42:41,380 --> 00:42:44,520
What determines which
corals have symbiosis,

986
00:42:44,520 --> 00:42:46,343
and is it by chance?

987
00:42:47,270 --> 00:42:49,513
- So that's a very good question.

988
00:42:50,810 --> 00:42:52,610
So corals are part of Cnidaria,

989
00:42:52,610 --> 00:42:55,580
which is like a really speciose phylum.

990
00:42:55,580 --> 00:42:56,413
As I mentioned,

991
00:42:56,413 --> 00:42:58,190
that includes jellyfish
and includes anemone.

992
00:42:58,190 --> 00:43:01,080
And then within like the coral category,

993
00:43:01,080 --> 00:43:02,140
there are hard corals,

994
00:43:02,140 --> 00:43:04,480
which are the ones that I've
been talking about today,

995
00:43:04,480 --> 00:43:06,730
known as scleractinians are
the ones that form reef,

996
00:43:06,730 --> 00:43:08,860
they like precipitate calcium carbonate.

997
00:43:08,860 --> 00:43:10,180
And then there's soft corals,

998
00:43:10,180 --> 00:43:12,780
which don't really form
like as hard of a structure.

999
00:43:13,900 --> 00:43:16,790
Both hard and soft corals
can have symbiosis.

1000
00:43:16,790 --> 00:43:18,680
Most scleractinian corals

1001
00:43:18,680 --> 00:43:20,940
of the reforming type have symbiont.

1002
00:43:20,940 --> 00:43:25,520
So there's maybe I wanna
say like eight or so species

1003
00:43:25,520 --> 00:43:29,700
of scleractinian corals that
have a facultative symbiosis.

1004
00:43:29,700 --> 00:43:31,470
So for instance, Oculina arbuscula,

1005
00:43:31,470 --> 00:43:33,590
the coral that I mentioned briefly

1006
00:43:33,590 --> 00:43:34,980
when I was talking about gene expression

1007
00:43:34,980 --> 00:43:37,180
is one of those corals.

1008
00:43:37,180 --> 00:43:40,120
And usually, the corals that
have a facultative symbiosis,

1009
00:43:40,120 --> 00:43:42,150
and by that, I mean that it can be

1010
00:43:42,150 --> 00:43:44,150
without symbionts and still be happy,

1011
00:43:44,150 --> 00:43:45,910
it doesn't actually die,

1012
00:43:45,910 --> 00:43:47,270
those are usually corals that live

1013
00:43:47,270 --> 00:43:50,510
a little bit further out of the tropics.

1014
00:43:50,510 --> 00:43:52,320
So there are species that have expanded

1015
00:43:52,320 --> 00:43:54,730
either for instance up
the Eastern Seaboard

1016
00:43:54,730 --> 00:43:57,140
or down into like New Zealand

1017
00:43:57,140 --> 00:43:59,880
into waters that don't
have as much sunlight,

1018
00:43:59,880 --> 00:44:04,010
and they rely instead on
increased heterotrophy.

1019
00:44:04,010 --> 00:44:06,280
So these kinds of corals
usually have like bigger polyps,

1020
00:44:06,280 --> 00:44:07,370
they feed a lot more,

1021
00:44:07,370 --> 00:44:09,620
and so they get most of
the nutrition that way.

1022
00:44:09,620 --> 00:44:10,760
But there's very few of them

1023
00:44:10,760 --> 00:44:13,140
that don't have obligate symbiosis

1024
00:44:13,140 --> 00:44:15,253
when we're talking about
reef-building corals.

1025
00:44:18,710 --> 00:44:20,280
- The next question is climate change

1026
00:44:20,280 --> 00:44:21,740
is causing many different species

1027
00:44:21,740 --> 00:44:24,460
to shift the ranges in
which they are found.

1028
00:44:24,460 --> 00:44:26,190
Is there any expectation that we might see

1029
00:44:26,190 --> 00:44:28,970
coral spread in areas not as hot?

1030
00:44:28,970 --> 00:44:33,040
You sort of touched on that,
but how likely is that?

1031
00:44:33,040 --> 00:44:34,980
- Yeah, so as I mentioned,

1032
00:44:34,980 --> 00:44:37,703
we've started to see a
little bit of that in Japan.

1033
00:44:38,630 --> 00:44:40,900
So there are areas in
Japan that used to be

1034
00:44:40,900 --> 00:44:44,720
entirely algal dominated a few decades ago

1035
00:44:44,720 --> 00:44:48,720
and now have started to see
really kind of wonderful

1036
00:44:48,720 --> 00:44:51,820
coral growth over the last few decades.

1037
00:44:51,820 --> 00:44:53,590
There aren't a ton of those examples.

1038
00:44:53,590 --> 00:44:57,692
And part of the reason is that corals are,

1039
00:44:57,692 --> 00:44:59,850
they grow slowly and they also,

1040
00:44:59,850 --> 00:45:01,340
they can disperse very widely,

1041
00:45:01,340 --> 00:45:04,210
but they need to have like
very specific conditions

1042
00:45:04,210 --> 00:45:06,360
in order to attach to a substrate.

1043
00:45:06,360 --> 00:45:10,570
So they want a very kind of curated mix

1044
00:45:10,570 --> 00:45:14,210
of bacterial and like algal chemical cues

1045
00:45:14,210 --> 00:45:16,010
that actually allow them to like swim down

1046
00:45:16,010 --> 00:45:18,630
and attach and be like, okay,
this is where I wanna live.

1047
00:45:18,630 --> 00:45:21,550
And so I think some of those
changes need to happen first

1048
00:45:21,550 --> 00:45:25,700
before corals can really start
expanding into new areas.

1049
00:45:25,700 --> 00:45:26,960
So there needs to be a little bit

1050
00:45:26,960 --> 00:45:29,020
of a shift in the ecosystem,

1051
00:45:29,020 --> 00:45:31,820
so that those chemical cues
that corals use to settle

1052
00:45:31,820 --> 00:45:35,340
and disperse are there for
them to actually attach

1053
00:45:35,340 --> 00:45:37,190
and then start forming reefs as well.

1054
00:45:39,700 --> 00:45:41,710
- Dr. Rivera, the next question is,

1055
00:45:41,710 --> 00:45:46,110
how long is a coral
bleached before it dies?

1056
00:45:46,110 --> 00:45:47,960
- That really depends on the species.

1057
00:45:48,950 --> 00:45:52,340
So there are certain
species like acroporas,

1058
00:45:52,340 --> 00:45:53,380
which are often the corals

1059
00:45:53,380 --> 00:45:56,310
that you see depicted in like movies.

1060
00:45:56,310 --> 00:45:59,520
And so for instance, this
coral here on the top

1061
00:45:59,520 --> 00:46:02,620
right there would be
an acropora type coral.

1062
00:46:02,620 --> 00:46:04,570
Those tend to be pretty sensitive.

1063
00:46:04,570 --> 00:46:08,100
And that's actually one of
the most speciose genus,

1064
00:46:08,100 --> 00:46:09,070
genera of corals.

1065
00:46:09,070 --> 00:46:12,060
So a lot of corals are very
sensitive to bleaching.

1066
00:46:12,060 --> 00:46:13,990
Some of the more resistant ones,

1067
00:46:13,990 --> 00:46:16,010
like that Porites that I work on,

1068
00:46:16,010 --> 00:46:18,010
that can be bleached for, you know,

1069
00:46:18,010 --> 00:46:21,080
maybe a month or two and still be okay.

1070
00:46:21,080 --> 00:46:24,413
The acropora start dying within
a few days to a few weeks.

1071
00:46:28,570 --> 00:46:31,030
- The next question is

1072
00:46:33,800 --> 00:46:36,060
climate change, I'm sorry,

1073
00:46:36,060 --> 00:46:39,160
temperature and pH reminds me
of denaturation of proteins.

1074
00:46:39,160 --> 00:46:40,830
Does this relate to the types of corals

1075
00:46:40,830 --> 00:46:43,800
that can't come back
from irreparable damage?

1076
00:46:43,800 --> 00:46:46,953
- Yes, so you're absolutely right.

1077
00:46:48,232 --> 00:46:50,850
Some of the things that
happen at a cellular level

1078
00:46:50,850 --> 00:46:52,500
when there's an increase in temperature

1079
00:46:52,500 --> 00:46:53,780
is protein denaturation.

1080
00:46:53,780 --> 00:46:56,500
So there's been a lot
of work that's been done

1081
00:46:56,500 --> 00:46:59,150
looking at, for instance,
gene expression changes

1082
00:46:59,150 --> 00:47:01,330
when you subject a coral to heat stress.

1083
00:47:01,330 --> 00:47:04,750
And some of the most resistant corals,

1084
00:47:04,750 --> 00:47:06,730
the genes that kind of seem to be involved

1085
00:47:06,730 --> 00:47:08,010
in helping them be resistant

1086
00:47:08,010 --> 00:47:10,240
are things that are called
heat shock proteins.

1087
00:47:10,240 --> 00:47:12,370
So these are proteins
whose job it actually

1088
00:47:12,370 --> 00:47:14,980
is to keep other proteins from denaturing.

1089
00:47:14,980 --> 00:47:17,280
And so when you have either

1090
00:47:17,280 --> 00:47:18,700
a high abundance of these proteins

1091
00:47:18,700 --> 00:47:20,330
or very effective versions
of these proteins,

1092
00:47:20,330 --> 00:47:22,620
you can kind of protect yourself

1093
00:47:22,620 --> 00:47:24,370
a little bit from that heat stress.

1094
00:47:25,320 --> 00:47:26,660
But nevertheless, there's like

1095
00:47:26,660 --> 00:47:29,670
only a limit to that kind of strategy.

1096
00:47:29,670 --> 00:47:31,210
But yes, it certainly does play a role,

1097
00:47:31,210 --> 00:47:33,560
especially at the
physiological cellular level.

1098
00:47:35,940 --> 00:47:39,810
- Dr. Rivera, the next
question is a deeper question.

1099
00:47:39,810 --> 00:47:42,020
Can you please explain a deeper connection

1100
00:47:42,020 --> 00:47:45,063
of how coral reefs came
about through evolution?

1101
00:47:46,860 --> 00:47:47,693
- Hm.

1102
00:47:50,560 --> 00:47:52,410
I'm not entirely sure
what the person means

1103
00:47:52,410 --> 00:47:55,980
by a deeper connection, but,

1104
00:47:55,980 --> 00:47:58,453
and I'm not like a reef paleobiologist,

1105
00:47:59,560 --> 00:48:01,340
so I don't know all that much about

1106
00:48:01,340 --> 00:48:05,400
like the very precise
intricacies of reef evolution.

1107
00:48:05,400 --> 00:48:07,330
But part of what we
think might have happened

1108
00:48:07,330 --> 00:48:10,790
is that the mutualism may perhaps

1109
00:48:10,790 --> 00:48:13,550
started off as a parasitism.

1110
00:48:13,550 --> 00:48:18,250
And so we had, first of all,
like coral reef environments

1111
00:48:18,250 --> 00:48:20,380
tend to be what's called oligotrophic,

1112
00:48:20,380 --> 00:48:23,270
meaning that the water
itself has low nutrients.

1113
00:48:23,270 --> 00:48:26,090
And so these symbionts want
higher nutrients, right?

1114
00:48:26,090 --> 00:48:28,530
And so you can get higher nutrients

1115
00:48:28,530 --> 00:48:30,760
if you're, say, inside
the stomach of a coral

1116
00:48:30,760 --> 00:48:33,550
that's digesting things
and releasing nitrogen.

1117
00:48:33,550 --> 00:48:35,620
And so perhaps this
might be one of the ways

1118
00:48:35,620 --> 00:48:37,290
in which that symbiosis first evolved

1119
00:48:37,290 --> 00:48:39,600
where the symbionts or
the algae in this case,

1120
00:48:39,600 --> 00:48:41,293
before there were really symbionts,

1121
00:48:42,350 --> 00:48:45,300
infected the corals to try to
steal some of those nutrients.

1122
00:48:45,300 --> 00:48:48,210
And over time, that exchange

1123
00:48:48,210 --> 00:48:51,150
evolved to be a mutualistic response.

1124
00:48:51,150 --> 00:48:53,200
And in fact, some of the
work that I've been doing

1125
00:48:53,200 --> 00:48:56,090
at Boston University is looking at,

1126
00:48:56,090 --> 00:48:57,850
kind of based off on that hypothesis,

1127
00:48:57,850 --> 00:49:01,300
how the symbiont modulates
the immunity of the coral.

1128
00:49:01,300 --> 00:49:02,370
And one of the things that we see

1129
00:49:02,370 --> 00:49:05,020
is that oftentimes when you have a coral

1130
00:49:05,020 --> 00:49:08,310
associated with its dominant symbiont,

1131
00:49:08,310 --> 00:49:10,260
there's essentially like
an immunosuppressive

1132
00:49:10,260 --> 00:49:12,160
element to that symbiosis,

1133
00:49:12,160 --> 00:49:15,390
where the symbiosis
causes a shutdown of genes

1134
00:49:15,390 --> 00:49:17,650
that have to do with immune response.

1135
00:49:17,650 --> 00:49:21,430
But when you have a symbiosis
with a symbiont species

1136
00:49:21,430 --> 00:49:23,610
that's not usually found with that coral,

1137
00:49:23,610 --> 00:49:25,800
that shut down doesn't happen.

1138
00:49:25,800 --> 00:49:27,610
Which seems to suggest that perhaps

1139
00:49:27,610 --> 00:49:29,370
that evolution of the symbiosis

1140
00:49:29,370 --> 00:49:31,170
was kind of this parasitic thing

1141
00:49:31,170 --> 00:49:34,620
where the symbiont that
was best at shutting down

1142
00:49:34,620 --> 00:49:36,750
the host immune response
and really sneaking in there

1143
00:49:36,750 --> 00:49:38,290
was the one that ended up establishing

1144
00:49:38,290 --> 00:49:40,040
this long-term symbiosis over time.

1145
00:49:44,360 --> 00:49:46,000
- Another question is,

1146
00:49:46,000 --> 00:49:48,260
where would you recommend
we start to help solve

1147
00:49:48,260 --> 00:49:51,723
some of these problems
plaguing the coral reefs?

1148
00:49:53,490 --> 00:49:56,140
- Well, as I mentioned, the
root cause is rising CO2,

1149
00:49:57,757 --> 00:49:59,740
so really trying to do
everything in your power

1150
00:49:59,740 --> 00:50:02,100
to both limit your own personal emissions,

1151
00:50:02,100 --> 00:50:05,700
as well as get our governments
and our climate treaties

1152
00:50:05,700 --> 00:50:08,110
to function and be effective mechanisms

1153
00:50:08,110 --> 00:50:11,560
for changing the trajectory that we're on.

1154
00:50:11,560 --> 00:50:13,460
It's probably the most powerful thing.

1155
00:50:15,390 --> 00:50:17,620
On a sort of more local scale,

1156
00:50:17,620 --> 00:50:20,650
you can get involved
in restoration efforts.

1157
00:50:20,650 --> 00:50:23,180
You can also get involved in
environmental advocacy groups

1158
00:50:23,180 --> 00:50:27,590
that seek to say, limit
runoff of certain chemicals

1159
00:50:27,590 --> 00:50:30,773
into coastal environments,
things of that nature.

1160
00:50:34,230 --> 00:50:37,110
- Dr. Rivera in your final summary slide,

1161
00:50:37,110 --> 00:50:40,240
your final bullet point is
collective climate action.

1162
00:50:40,240 --> 00:50:43,083
And my colleague Nelson
asked you a question

1163
00:50:43,083 --> 00:50:45,570
that was heading down those lines.

1164
00:50:45,570 --> 00:50:49,690
The next question is similarly phrased,

1165
00:50:49,690 --> 00:50:51,480
but once I read it and you've answered it,

1166
00:50:51,480 --> 00:50:53,660
I was wondering if our colleague,

1167
00:50:53,660 --> 00:50:55,440
Dr. Popolizio might rejoin us.

1168
00:50:55,440 --> 00:50:58,240
She has a question to ask.

1169
00:50:58,240 --> 00:51:00,210
And we have a little bit of time,

1170
00:51:00,210 --> 00:51:03,550
maybe we can also talk
about what other things

1171
00:51:03,550 --> 00:51:07,180
we can do collectively at
the sort of grassroots level

1172
00:51:08,060 --> 00:51:09,890
to help our coral reefs.

1173
00:51:09,890 --> 00:51:11,710
So the question I have is,

1174
00:51:11,710 --> 00:51:14,050
do they have protection laws put in place

1175
00:51:14,050 --> 00:51:18,110
and do they treat the reefs
like they protect forest parks

1176
00:51:18,110 --> 00:51:20,643
to stop the continuation of bleaching?

1177
00:51:22,330 --> 00:51:24,810
- So the short answer to
that question is, yes,

1178
00:51:24,810 --> 00:51:27,500
there are some reefs that are protected.

1179
00:51:27,500 --> 00:51:30,060
There are not as many as probably

1180
00:51:30,060 --> 00:51:33,090
should be protected, in my opinion.

1181
00:51:33,090 --> 00:51:37,343
So protected areas in
the ocean are actually,

1182
00:51:37,343 --> 00:51:40,108
there's a pretty small overall

1183
00:51:40,108 --> 00:51:42,230
surface area of ocean that is protected.

1184
00:51:42,230 --> 00:51:45,030
I believe the number is
between like less than 1%.

1185
00:51:47,026 --> 00:51:49,080
And a lot of the kind
of levels of protection

1186
00:51:49,080 --> 00:51:51,700
really vary depending on the country

1187
00:51:51,700 --> 00:51:55,340
and the type of protection
strategy that's being used.

1188
00:51:55,340 --> 00:51:57,280
So it could be that you have a reef area

1189
00:51:57,280 --> 00:51:58,840
that's quote, unquote protected.

1190
00:51:58,840 --> 00:52:01,980
But what that means is that
maybe you're not allowed

1191
00:52:01,980 --> 00:52:04,350
to fish there during a
certain part of the year,

1192
00:52:04,350 --> 00:52:07,900
or maybe you're not allowed to dock there

1193
00:52:07,900 --> 00:52:10,580
or use anchors there or things like that.

1194
00:52:10,580 --> 00:52:12,380
There's very few protected areas

1195
00:52:12,380 --> 00:52:13,870
that are kind of blanket protection,

1196
00:52:13,870 --> 00:52:15,150
like you really shouldn't go there.

1197
00:52:15,150 --> 00:52:16,890
You're not really allowed to be there

1198
00:52:16,890 --> 00:52:18,640
unless you have special permission.

1199
00:52:18,640 --> 00:52:19,900
And there's a few of those,

1200
00:52:19,900 --> 00:52:22,923
but these are usually places
that are already very remote.

1201
00:52:24,060 --> 00:52:26,160
So for instance, a lot of the work

1202
00:52:26,160 --> 00:52:27,550
that I also did in the Central Pacific

1203
00:52:27,550 --> 00:52:29,720
is in a place called the
Phoenix Island Protected Area,

1204
00:52:29,720 --> 00:52:32,420
which is one of the largest in the world.

1205
00:52:32,420 --> 00:52:34,680
And it's a really
beautiful, amazing nation.

1206
00:52:34,680 --> 00:52:37,580
And most of the use of that region

1207
00:52:37,580 --> 00:52:40,000
before it was protected
was for tuna fisheries.

1208
00:52:40,000 --> 00:52:42,260
So these are open ocean fisheries

1209
00:52:42,260 --> 00:52:45,080
that aren't really going
near the reefs all that much.

1210
00:52:45,080 --> 00:52:46,710
Now that that entire area is protected,

1211
00:52:46,710 --> 00:52:49,230
there's no fishing allowed
anywhere in that region.

1212
00:52:49,230 --> 00:52:51,150
And that's also helped the briefs recover,

1213
00:52:51,150 --> 00:52:54,270
'cause it always helps to not have humans

1214
00:52:54,270 --> 00:52:56,413
coming in and taking
things out of the water.

1215
00:52:57,290 --> 00:52:59,080
But those types of really big

1216
00:52:59,080 --> 00:53:01,123
blanket protections are quite rare.

1217
00:53:02,100 --> 00:53:03,870
They're getting more
common, which is good.

1218
00:53:03,870 --> 00:53:05,540
But that's another thing
that you can do to help

1219
00:53:05,540 --> 00:53:07,090
is kind of encourage the formation

1220
00:53:07,090 --> 00:53:09,840
of marine protected areas
in your local environments

1221
00:53:09,840 --> 00:53:12,140
and the governments that
you have some say in.

1222
00:53:16,430 --> 00:53:18,930
- Dr. Popolizio, you're back with us.

1223
00:53:18,930 --> 00:53:21,880
- Yes, sure, I was curious about,

1224
00:53:21,880 --> 00:53:26,480
I guess my question is
related to coral reproduction,

1225
00:53:26,480 --> 00:53:29,000
and I'm wondering, when you were talking

1226
00:53:29,000 --> 00:53:33,327
about the differences in
the population genetics

1227
00:53:35,070 --> 00:53:39,532
between the rock islands
and the outer reef in Palau,

1228
00:53:39,532 --> 00:53:42,450
if there's any evidence of gene flow

1229
00:53:42,450 --> 00:53:45,650
between those two regions in the reef.

1230
00:53:45,650 --> 00:53:48,620
- Yeah, so there's, sorry,
go ahead and finish.

1231
00:53:48,620 --> 00:53:51,919
- If that would have an
impact on the resiliency

1232
00:53:51,919 --> 00:53:54,510
of the corals on the
outer reef at some point

1233
00:53:54,510 --> 00:53:57,660
if there was genetic exchange.

1234
00:53:57,660 --> 00:54:00,060
- Yeah, so there certainly
is a genetic exchange

1235
00:54:00,060 --> 00:54:03,969
in the sense that, so
the lineages themselves,

1236
00:54:03,969 --> 00:54:07,760
if I look at genetic differentiation
between those groups,

1237
00:54:07,760 --> 00:54:10,810
so the dark blue, the light
blue, the pink, and the red,

1238
00:54:10,810 --> 00:54:12,260
they're quite diverged.

1239
00:54:12,260 --> 00:54:15,700
So gene flow between those
lineages is quite limited.

1240
00:54:15,700 --> 00:54:18,210
However, it's not that the lineages

1241
00:54:18,210 --> 00:54:21,200
that are more tolerant are
only found in the rock islands.

1242
00:54:21,200 --> 00:54:24,260
So there were some of those
individuals in the outer reefs.

1243
00:54:24,260 --> 00:54:26,600
And when we actually look at
those specific individuals

1244
00:54:26,600 --> 00:54:28,240
and look at their stress bands,

1245
00:54:28,240 --> 00:54:30,580
even when they're in the
outer reef environments,

1246
00:54:30,580 --> 00:54:31,820
they're still bleaching less,

1247
00:54:31,820 --> 00:54:33,270
which suggests that they're retaining

1248
00:54:33,270 --> 00:54:36,070
that thermal tolerance that's
perhaps genetically based.

1249
00:54:37,510 --> 00:54:41,010
So that does lend some
hope in the sense that,

1250
00:54:41,010 --> 00:54:43,770
if say the outer reef
environments are decimated

1251
00:54:43,770 --> 00:54:46,120
by a mass bleaching event over time,

1252
00:54:46,120 --> 00:54:48,540
larvae from the rock
islands can make it out

1253
00:54:48,540 --> 00:54:51,360
to the other reefs and help
replenish that population

1254
00:54:51,360 --> 00:54:53,410
with more thermally tolerant individuals.

1255
00:54:54,400 --> 00:54:57,000
So yes, that was essentially
your question, right?

1256
00:54:57,000 --> 00:54:58,343
- Yeah, thank you.
- Yep.

1257
00:54:59,590 --> 00:55:00,973
- We have another question.

1258
00:55:02,059 --> 00:55:04,950
I know that a lot of fisheries
try to restore coral reefs

1259
00:55:04,950 --> 00:55:08,670
by placing nursery grown
corals back onto the reefs.

1260
00:55:08,670 --> 00:55:10,570
How do they build up coral resilience?

1261
00:55:15,395 --> 00:55:18,060
- I'm not entirely sure I
understand the question.

1262
00:55:18,060 --> 00:55:23,060
Is it why, or how nurseries
promote resilience?

1263
00:55:23,096 --> 00:55:27,310
- I'm not sure, but I think
that what they're saying is,

1264
00:55:27,310 --> 00:55:29,560
can those nursery grown corals

1265
00:55:29,560 --> 00:55:32,850
sort of repopulate and provide resilience?

1266
00:55:32,850 --> 00:55:36,920
I guess, that sort of the way
I interpret that question.

1267
00:55:36,920 --> 00:55:38,760
- Yeah, so they certainly can.

1268
00:55:38,760 --> 00:55:42,610
And so restoration efforts,
they certainly can,

1269
00:55:42,610 --> 00:55:44,830
but they're kind of very limited

1270
00:55:44,830 --> 00:55:46,890
in the impact they can have.

1271
00:55:46,890 --> 00:55:50,610
One reason being that
corals grow very slowly.

1272
00:55:50,610 --> 00:55:52,540
So it takes a really long time,

1273
00:55:52,540 --> 00:55:55,800
like a decade to grow a coral in a lab

1274
00:55:55,800 --> 00:55:58,330
to like kind of like this size

1275
00:55:58,330 --> 00:56:00,550
to then be able to put it out on a reef.

1276
00:56:00,550 --> 00:56:05,110
And oftentimes, if you
put it out on a reef

1277
00:56:05,110 --> 00:56:08,360
and then it gets really warm on that reef,

1278
00:56:08,360 --> 00:56:10,370
that nursery coral is not gonna

1279
00:56:10,370 --> 00:56:12,740
necessarily be immune to that warming,

1280
00:56:12,740 --> 00:56:15,860
even when you might've tried
to like kind of optimize

1281
00:56:15,860 --> 00:56:18,530
for more thermally tolerant genotypes.

1282
00:56:18,530 --> 00:56:21,100
And so restoration efforts are important

1283
00:56:21,100 --> 00:56:22,170
and they can certainly help

1284
00:56:22,170 --> 00:56:24,300
if you're seeding in
area that has nothing,

1285
00:56:24,300 --> 00:56:28,460
but it's not gonna be, like
we can't do it at the scale

1286
00:56:28,460 --> 00:56:30,340
at which it would actually be like

1287
00:56:31,411 --> 00:56:33,211
the sort of saving grace for corals.

1288
00:56:34,484 --> 00:56:36,200
And there's a lot of people putting in

1289
00:56:36,200 --> 00:56:39,140
very amazing efforts to
make it more efficient

1290
00:56:39,140 --> 00:56:43,380
and make it more amenable
to larger scale restoration,

1291
00:56:43,380 --> 00:56:44,930
but it's still not quite there.

1292
00:56:52,940 --> 00:56:54,690
- I'll follow up with
them with another one.

1293
00:56:54,690 --> 00:56:57,470
Does higher biodiversity
increase the odds of corals

1294
00:56:57,470 --> 00:56:59,520
tolerating or surviving bleaching events?

1295
00:57:01,130 --> 00:57:03,460
- So that's a good question.

1296
00:57:03,460 --> 00:57:06,130
And the short answer is yes.

1297
00:57:06,130 --> 00:57:08,550
The longer answer, that
it's kind of complicated.

1298
00:57:08,550 --> 00:57:12,900
So when you have a really biodiverse reef,

1299
00:57:12,900 --> 00:57:15,080
that can often promote resilience

1300
00:57:15,080 --> 00:57:16,620
'cause you have higher genetic diversity

1301
00:57:16,620 --> 00:57:18,500
and you maybe have more species of corals,

1302
00:57:18,500 --> 00:57:19,770
some of which might be more tolerant,

1303
00:57:19,770 --> 00:57:21,020
some of which might be less tolerant.

1304
00:57:21,020 --> 00:57:23,660
And so the ones that are
more tolerant can live

1305
00:57:23,660 --> 00:57:25,890
and they can still maintain
the reef structure.

1306
00:57:25,890 --> 00:57:27,840
That's gonna help recruit new corals

1307
00:57:27,840 --> 00:57:30,200
to come back and regrow.

1308
00:57:30,200 --> 00:57:33,523
So there's all sorts of interplay
that happen at that scale.

1309
00:57:34,600 --> 00:57:38,980
I don't know that I can
speak to like specifically,

1310
00:57:38,980 --> 00:57:41,770
if like biodiversity itself

1311
00:57:41,770 --> 00:57:44,490
is gonna facilitate thermal tolerance.

1312
00:57:44,490 --> 00:57:45,470
I can't think of a mechanism

1313
00:57:45,470 --> 00:57:47,010
by which that's necessarily the case.

1314
00:57:47,010 --> 00:57:49,560
It's more through these
like interactive feedbacks.

1315
00:57:53,440 --> 00:57:56,700
- Thank you so much, Hanny,
for that fascinating talk.

1316
00:57:56,700 --> 00:57:59,190
I think many people can appreciate

1317
00:57:59,190 --> 00:58:01,800
the beauty and wonder of coral reefs

1318
00:58:01,800 --> 00:58:04,700
and also know that they're
threatened by human activities.

1319
00:58:04,700 --> 00:58:08,420
But you've allowed us today
to go beneath the surface,

1320
00:58:08,420 --> 00:58:11,850
pun intended, and get a
sense of the complexity

1321
00:58:11,850 --> 00:58:16,040
and diversity of their
responses to their environment

1322
00:58:16,040 --> 00:58:19,070
and how the work that
scientists like you do

1323
00:58:19,070 --> 00:58:22,350
is so vital to our
ability to protect them,

1324
00:58:22,350 --> 00:58:24,590
as well as the policy decisions

1325
00:58:24,590 --> 00:58:27,380
we make with respect to climate.

1326
00:58:27,380 --> 00:58:28,560
So thank you.

1327
00:58:28,560 --> 00:58:29,550
- Thank you so much for having me.

1328
00:58:29,550 --> 00:58:30,383
It was great.

1329
00:58:30,383 --> 00:58:32,820
And thank you, everyone, for
all the amazing questions.

1330
00:58:34,250 --> 00:58:36,403
- Thank you as well, Dr. Rivera.

1331
00:58:36,403 --> 00:58:37,840
And thank you to our audience.

1332
00:58:37,840 --> 00:58:39,620
We'll see you tomorrow at 11:00 a.m.

1333
00:58:39,620 --> 00:58:42,070
for our next talk on day three.

1334
00:58:42,070 --> 00:58:44,113
Bye bye.
- Bye.