Importance of Natural Resources

Ocean Species Respond to Climate Change — HHMI BioInteractive Video


[music plays] [ANNOUNCER:] Welcome to HHMI’s 2014
Holiday Lectures on Science. [music plays] This year’s lectures, “Biodiversity in the Age of Humans,” will be given
by three of the world’s leading experts in the study of biodiversity
and conservation biology. Dr. Anthony Barnosky,
of the University of California, Berkley; Dr. Elizabeth Hadly,
of Stanford University; and Dr. Stephen Palumbi, also of Stanford University. The fifth lecture is titled “Ocean
Species Respond to Climate Change.” And now, Dr. Stephen Palumbi. [applause] [PALUMBI:] Welcome back. Thanks for coming back. I’m going to talk
about climate change in the oceans. And when we think about climate change
it’s a global issue. Liz and Tony have talked
a lot about it a lot, and there’s features of climate change
in the ocean and on land that are pretty much the same, particularly at the borders of the ocean
and the land where rising sea level and increased storms increasingly
mean that our coastlines are pummeled by waves and the destruction
of large storms like Hurricane Sandy. And that is something
that we can understand from both sides, the terrestrial and the ocean side. Well there are a couple things
about climate change that are really different in the ocean. And probably the most
important one is ocean acidification. Now ocean acidification comes about
because as we pump CO2 into the atmosphere, then that dissolves back into the ocean
and makes carbonic acid. That carbonic acid increases the acidity
of the ocean and affects marine life. Now I’ve just dropped here
a piece of coral in vinegar. Now vinegar is 100,000 times
more acidic than the ocean will ever be and these corals
are bubbling because the acid and the calcium carbonate
are interacting to release CO2. That is not going to happen
in the future oceans because this is vinegar, but the principle is the same. That, as the acidity
of the ocean goes up, and it’s increased 26%
over the last couple decades, those shells–the skeletons of corals, the shells of gastropods–are harder
to make and easier to dissolve. And so that changes the way
ocean life lives and our entire ocean. Now I mentioned in the last lecture
that it’s the biggest biological habitat known in the universe
and we’re changing its basic chemistry. Not only are shells harder to make, but actually nervous systems
are harder to work. Some really interesting research
out of Australia has shown that when fish are subjected
to very high levels of CO2 in the water, it changes the pH and it changes the way
their nervous systems function. They no longer evaluate the risk
of predators correctly and so they leave themselves out to
predation risk to a much higher degree. Their growth rate suffers,
the growth rate of many marine species suffer when acidification becomes
more and more and more of a problem. The other major threat,
the fourth major threat of climate change
in the oceans is warming. Similar to on land,
but what I’m going to talk to you about is how that affects
particular ocean species. This is a map
from earlier this month of the Pacific. Now the red and the dark red colors
are areas of the Pacific that are a degree or two warmer
than expected for this time of year, temperature anomalies. Now those areas
are washing across the Pacific. About a week
ago I was on the big island of Hawaii, which is that little spot
right down there, and what we were seeing
there was coral bleaching, that is we were seeing the reaction
of corals to this warm water in ways that are very detrimental
to the reefs themselves. So we’ve got good satellite maps
of what’s happening out there in terms of the temperature of the ocean and what I’m going to talk to you a bit about is how species
respond to that and then what we know about how they might actually
survive it or not in the future. I’m going to talk to you
a lot about corals and I’m going to talk to you
about how they interact with the climate and I’m going to sort of present them
in at first a little bit of a sort of paleontological way, like Tony said, because in a lot of ways corals
have been major survivors in our planet. They were born as a group of organisms
about 250 million years ago. They have survived two mass extinctions, they have been major players
of the oceans of the planet for most of that 250 million years. So from that standpoint
they seem like survivors, they’re good at mass extinctions, they’re good at all kinds
of environmental change, but when we turn around we
see that in fact a lot of the things that we do on our planet
right now seem to be killing them. Loss of coral cover over the last couple
of decades is up to about 40%, and that’s because of sedimentation
kills corals, pollution kills corals, overfishing kills corals because algae
grew up all over the corals, acidification slows down their growth
and the temperature of the water when it goes up causes corals
to bleach and die. So here’s the conundrum,
they’re survivors, they live through a quarter
of a billion years, and they’re dying now every time
we do something. What is that? How can they be so strong
and so wimpy at the same time? Well you can boil that
down into a couple of different hypotheses
about what might be going on, and here’s two
that seem to be the strong ones. Maybe, even though they’ve lived
a quarter of a billion years, what we’re doing on the planet
now is on an unprecedented scale and rate of environmental change,
they just cannot handle. Or maybe corals
have really unknown abilities to survive and deal
with strong environmental change that we don’t know about yet
that they’ve used to survive cataclysm’s even though right now we
see their numbers dropping. So I’m going to go through these two
and look at them. It turns out they’re both true. And the fact that it’s
such an unprecedented rate of change is really directed our research
over the last 10 years to look for how corals are reacting. The example that we’re going to use
is the rate of change, Tony talked about the rate of extinction and I’m going to talk about the rate
of temperature change. What’s shown here on the left-hand side
is the last 150,000 years. In particular I want you to focus
on the last 20,000 years ago or so. This is the recovery
from a major ice age, the temperatures in the world
increased by about 7 degrees Centigrade, so what’s the rate
of temperature increase in this really strong recovery
from an ice age? We draw the line,
7 degrees over 10,000 years is .07 degrees Centigrade per century. How does that compare
with the increase in temperature that we’re seeing now in the world? That’s the right-hand graph that’s the increase
in global average temperatures in the oceans over the last 100 years
or so. We draw the same kind of line and it’s .8 degrees in a century. That’s 11 times higher than that, which means
that as we are changing the world, not only are we
increasing the temperature, but we’re doing it at 11 times the rate
that occurred even if we pick one of the biggest changes of temperature
in the recent history of life. So we are having a really big impact
on the world. It may be unprecedented. And let’s go to the next question and say well okay how do corals
then react when these changes happen? I’ve mentioned bleaching a couple
of times. What is that? A coral animal is a skeleton
with a tissue layer on top of it. The tissue layer
is generally tan or brown, but it’s not because of the coral. It’s tan or brown because corals
have an internal cellular symbiont, an dinoflagellate alga
called Symbiodinium, and heating causes the Symbiodinium
to be expelled from the corals and what you see
is the transparent tissue of the coral with the white skeleton underneath, that’s coral bleaching. Well it turns out that understanding
that involves an incredible integration of remote sensing in the world, ecology, the cell biology of corals, even the molecular biology
of photosynthesis. And what I want to do
is take you on a little tour of that now just to see how this works. Now corals are small animals, but they build structure
that you could actually see from space. And as we zoom in we see the reefs
where I work on a little island called Ofu in America Samoa, the ridge
there, the edge is the coral reef and as we zoom in we
see what those reefs are. Now the reefs are made
of individual coral colonies like we see now. That coral then is actually made up
of a whole series of small polyps they’re called. This is a colonial organism, and the polyps themselves have
all the structures that an animal needs. It has a mouth, it has tentacles,
it has gonads, it can live, it can reproduce, it can grow. They’re in a colony
of genetically identical polyps. Now the color on these tentacles,
like I said, is not the color of the coral itself, it’s the color of the symbiont, and as the focus racks
in and out a little bit here, then what we see is that we can just see
the little globules of the symbiont. Well let’s take a closer look. We’ll go into a tentacle and see those. These cells, the symbionts,
are not just floating around, they’re actually inside the coral cells. Corals are simple,
they just have two cells layers: an epidermis and a gastrodermis inside. The symbionts
are inside the gastrodermis, and you can see it there. Now this is a life form
called a dinoflagellate. It has chloroplasts
because it’s photosynthetic, but it has very odd-shaped chloroplasts
like these yellow structures here. We’re going to zoom
in to the chloroplast itself because that’s where the damage
happens during bleaching. What do chloroplasts have in them? They have membranes
called thylakoid membranes. Those membranes hold the proteins
called the photosystems that then capture light energy
and turn it into chemical energy. It’s the molecules
that capture all of the sunlight that we get on the planet
to make the food that we eat. The rain of photons
down here hits these photosystems and they gather them up. Now if the temperature goes up
and if the light goes up, then they freak out. There’s too much energy,
the photosystems break and they no longer
can function the way they do, but the rain of photon
keeps going, the energy is still there, and as a consequence that energy is now turned
into making reactive oxygen molecules Those are damaging to cells, so
it damages the inside of the symbiont, it damages the inside of the coral cell
and they spit the symbiont out. That spitting of the symbiont
out by one coral cell isn’t bad, but if the entire colony does it,
then that’s coral bleaching. What you can see here
is simulated of the spitting out of these symbionts
and the gradual whitening of this particular part
of this particular coral colony. Well when that happens
across an entire colony, then the coral turns
from its normal tan color into a white color. What difference does that make? The symbiont provides 75-80%
of the energy the coral needs to survive and without that energy, it can’t make a skeleton
and it can’t live very long. So as a consequence a lot of the corals
that bleach eventually die, then that destroys the reef
in a very severe bleaching event, then many corals on a reef will succumb
and take decades to recover. Well we were interested in this process, we were interested in how corals might actually not just
be affected by this, but also how we might work
with different systems to try to find out what corals can do
to circumvent some of these problems, or that anything
they could do to survive better in the case of bleaching conditions. We found a place to do that, which is in Ofu Island,
in American Samoa, because it’s one
of the best laboratories for coral science
that we’ve been able to find. [PALUMBI (in video):] Ofu Island
and the lagoon behind the reef here is one of the best coral
laboratories in the world. Because the best low tides
are often during the middle of the day, these back reef lagoons heat up to an extraordinary degree
for a coral reef. They heat up to 32, 33, 34° centigrade. That’s above the temperature in which most corals
will bleach and die, yet these lagoons
are full of thriving, growing corals of many, many species. So the question
is how do these corals do it? How do they live
in such warm temperatures? Because the theory is
those temperatures should kill corals. [PALUMBI:] So how do we do that, how do we work with the corals
in places like American Samoa to try to understand how they’re related
to bleaching and heat resistance? So this is the lab
that we’ve built in America Samoa. It may not look like much, but it’s actually
an incredibly important facility for us because we’ve been able
to standardize the heat stress that we can apply to corals. We can provide them with a mimic
of the kinds of heat they’ll get actually
on an Ofu coral reef and see how they react. So these tanks actually have heaters
and chillers in them, they have lights, they have flow-through water system, they’re controlled by that laptop
on the right-hand side, and we can use those little tanks to mimic what these corals will see
during a very strong bleaching day out there in Ofu. What do we see? We see this. We see corals that come out
of the same tank looking very different. The coral on your left is bleached. It’s lost most of its symbionts. The coral on the right
though is not bleached. It came out of the same tank, it got the same heat,
it’s the same species. The only difference is that, the coral on your left was living
in a very cool part of the reef, but the coral
on the right, same species, was living in a warmer part of the reef. So we know from this
that different corals react differently to the same bleaching temperatures. Some bleach like they’re predicted to, but some are resistant to that. So the question that we really
began to ask is how do they do that? How do corals
become resistant to bleaching? Does it happen quickly? Can all corals do that? That’s why Ofu has been a really
important research site for this. How would you find that out? Well the way we approached
that was by transplanting them. Corals are really
effectively great experimental animals because you can break them and you can transplant them
to different parts of the reef. These are just some corals that have
been living on a different part of the reef for about two, three years. The numbers there is the number
of the colony. We know where it’s from,
we can transplant them. So the way this experiment works is
that well we find a coral on the reef, we number it
and tag it and measure its temperature, we take it, break it in two, and then we transfer one part
to the warmer part of the reef. We transfer the other part
to a cooler pool in the same reef, let them grow for a couple
of years, monitor them, take pictures of them,
keep track of how they’re doing, and then we put them
back in the coral stress tank. We then look to see for the same coral that has been living for a couple years
in different environments how that affects
their bleaching resistance. And this graph here shows that the coral
in this one colony named colony AH02 that was living in the warmer pool, that colony has a much higher resistance
to bleaching than the exact same genetic colony that was living for two years
in the cooler pool. That’s the blue bar there.
We can do that a lot. These are all different colonies
of the same species from different parts of the reef, and every time we move them
into the warmer pool they gain heat resistance, and every time we
move them to the cooler pool they lose heat resistance. It means that in fact they can acquire
this trait, heat resistance, at least to some extent. Well what is that called? That’s actually called acclimation. So two responses
to changing environments that most organisms
and populations have are acclimation. That’s the adjustment of an individual’s
physiology to new conditions. Now, we can do that. For example Liz was telling you
that if you move to Denver you’d have 83% of the oxygen available to you
than if you lived at sea level. And if we do that not only
would we breathe a little heavily, but we’ll start making more hemoglobin
in our red blood cells. That’s an acclimation to high elevation. Well the reaction that corals
have to temperature is an acclimation, their physiology is changing. But there’s another way
that populations can respond, that’s normal Darwinian evolution
or adaptation. That’s natural selection
for the individuals that have the right genes
for new conditions. So these two things acclimation and adaptation are pretty common
in the biological world. We’ve just shown you
that acclimation can happen in corals and it happens quickly, within at least a couple
of years, maybe faster, within an organism’s life span. Adaptation also happens
we think in corals, but happens a little bit more slowly. It has to happen over generations. Well how can we look
at whether adaptation is happening if we don’t have generations of coral life
in order to do those studies? The way
we do that is because I’m a geneticist, we look at the genes
that these corals have, we look at the genes that the corals
have living in different environments, and given new sequencing technologies
we can actually sequence most of the protein coding genes
of each of these individual corals and look across about 25,000 genes
for those that relate to temperature. And we do that, we find genes
that are related to temperature. This is just one of them. And what it shows is that individual
corals living at warmer temperatures, that is time
above 31 degrees here on the Y axis, those corals
tend to have a particular allele, that’s called B here, at a gene, whereas corals that live
in the cooler parts of the reef tend to have an A allele
at the same gene. A and B allele
is just different versions, different DNA sequences at the same gene,
doing the same sort of thing. But what it tells us
is that the individual corals in this particular genetic locus are different depending
upon the temperature they live in. There are about 100 genes
like this in corals, and they distinguish the corals
living in the warmer pools in Ofu from the corals
living in the cooler pools in Ofu. A map shows that, these dots are individual corals
placed on the reef that’s there. We know their GPS coordinates,
we’ve tagged them, we know what temperatures
they have seen every six minutes over the last three years. And the cool pool corals also
and these warm pool corals we know which alleles
they have at each of these 100 loci. And what I’m showing you here
is that most of the cool pool corals don’t have many of the warm pool
alleles, some have some. The warm pool corals tend to have
a lot more of the warm alleles at these genes than the cool pool ones. So this shows that genetically, although these corals
are pretty similar to one another, they’d never be called different species
because of these genetic differences, there are about 100 genes
at which they differ. Right now we’re trying to chase down what those genes are and how they
might act to provide heat resistance. We also can tell that these,
the whole population here has the genetic reservoir
and in order to be able to adapt. Liz was talking a little bit about this
for tigers where those reservoirs may not occur in places
that have high bottlenecks, but in this case
in these corals they do occur. What are the implications
of this kind of work for corals and for climate change, because this is just one species
in one place? It tells us that these corals can become more resistant
to climate change through acclimation and they can adapt. We know though that this ability
is limited. They can’t acclimate forever,
they can’t acclimate to 100 degrees. What the limits are
and when those corals will reach those limits is something
we don’t know right now. It’s an active area of research. What we can say is
that although climate change is coming and heat is going up,
these corals can respond. That’s good news, they can respond. It’s not going to give us forever. It’s not going to solve the problem. It might however give us a little
extra time to solve the problem. It might give us a couple extra decades
say before ocean warming gets to the point where the ability
to acclimate is exhausted or the ability to adapt is exhausted. What we tried to think about for that
is not that this solves our problem, but that it gives us
a little extra time. Another way to think about it
is we should not waste that time because we have a little bit
more time than we thought. I showed you this picture before
because there are some things you can do in the ocean
to try to help the health of the ocean and help the life of the ocean. This is an example
of a marine protected area that has allowed
these fish to grow large and play a different role
in the community, that role is tourism here. Now those big fish, the bumphead wrasse you can also find
not only in the Great Barrier Reef, but on menus, and in seafood restaurants, particularly
the lips of a bumphead wrasse you can find
at very high end seafood restaurants. They’re very expensive,
about $200 for the lips, that’s $100 for each lip. But the value of that fish to tourism is vastly higher because people come to
take pictures of this individual fish. It hangs out on one spot
on the Great Barrier Reef and people know where it is. They come to take pictures. So the estimated value of this fish
to that local economy is over $2,000 a year just
for people coming to take its picture. So the economy
of protecting parts of the ocean is actually a lot better sometimes
than the economy of using it. What about our little island
and our little corals? Well this is the runway on Ofu Island. It’s a very short runway
and not many planes can land on it. I’m actually, from this picture
I’m flying in the only plane in the Samoan archipelago
that can land on that runway. The people that live there would like
the runway to be a little bit longer so more planes could land
and their tourism base could go up. So where do you think
in the Pacific Ocean, the Pacific’s most heat-resistant corals
live? Just guess. You know the answer. It’s right there. Any extension of this runway
in that direction will wipe out these corals. Now they’re resistant to heat, but they are not resistant
to bulldozers. So one of the ways we can use
this research is to say all right, these are areas
because they are climate resistant might be good candidates
for protection of these reefs. Maybe we should protect those reefs
in the future because they have the genes in order
to live longer under future conditions. The second thing
we could think about doing is whether or not if we had those corals we could transplant them
to other reefs close by, maybe just around the corner
that are not heat resistant in order to build heat-resistant reefs
into the future. We don’t know if we can do that. We’ve just started that experiment now. I want to show you a little bit of that. These are some coral nurseries that we just put out
in America Samoa this last August. Half of these corals
are from the warm pool that are heat resistant,
half of these corals are from the cooler part of the reef
that are not heat resistant. We’ve taken over the mountain
to the other side of the island and put them down there in order
to be able to see whether or not they’re going
to grow into heat resistant corals. We’ve had great help
from a local Samoan construction team that built those cement pads for us
and then helped us put them out there. And the idea here is to simply see
when we grow corals from these different pools
in a different spot, whether they bring their heat resistance
with them. We’re going to go back
over the next couple of months and test these corals
in their nursery state to see if they still are heat resistant. Because of the balance
in acclimation and adaptation we know they’re going
to lose some of their heat resistance, but we think they’re going
to retain about half of it. That’s our prediction Well what I’ve tried to do
is show you a lot about the oceans, the kinds of threats they’re under, the kinds of creatures
that are out there, and the sorts of ways
they are responding to climate change. We also have to respond
to climate change, the call here, and I’m going to repeat what Tony said, this is the century of choice. This is where we can choose
whether or not the oceans are going to basically
move along with us into the future or dramatically change in the future and then drop all the services
that they provide. For me I just took that picture a month
ago along the coast of Kona. I would love for you to be able to take
a picture like that in the future and let’s just try to make
it work that way. Thanks. [applause] Questions? Yeah. [STUDENT:] Are temperature-tolerant
genes dominant or recessive and could changing
climate affect the phenotype, make it
so that the tolerant ones are expressed? [PALUMBI:] Great question.
So are they dominant or recessive? They’re what’s called co-dominant, at least in the cases
that we know about. So that if you have two warm-
adapted alleles, you’re twice as warm
adapted as if you just had one. And if the environment changes, then
what else changes is another question? And what we find happening
is when the environment gets a little warmer
then actually the expression of genes changes, not just the physiology, but we can trace
the physiological acclimation down to the genes
that get turned on and off. And what’s really cool is that some
of the alleles that are warm adapted actually are just expressed
at a higher level than other genes. And so we’re beginning now to look
at the wiring of all that and learn how the molecular biology
of gene expression actually translates into the fitness
of corals and future reefs. That’s just one of the ways that I think that marine biology
and molecular biology and all of these different realms
really work together. One more question. [STUDENT:] How can we educate people about the benefit of ecotourism versus poaching and killing these animals for profit? [PALUMBI:] The question is how do we
educate people about those benefits? Actually it’s pretty easy,
you just show them the numbers because these are people locally
who are gaining those values and when they see the numbers, then they say oh well let’s not
kill them, let’s just leave them there. So that’s it for questions right now. Thank you so much. [applause]


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