Keystone species and conserving our delicate food webs | Agnes Mittermayr | TEDxProvincetown


Translator: Ian Edwards
Reviewer: David DeRuwe In a time when successful
conservation laws are under attack and threatened to be rolled back, we need to get creative
about how we want to protect nature and save species from extinction. One approach is to look at the past and see how relationships between species
have changed over time. Our planet has been through
five mass extinctions, during which 50% to 90%
of all species on Earth were lost. Imagine, suddenly,
no badgers, no crickets, no emus! In the 1980s, scientists realized that we are losing
species faster than usual and predicted that we could lose half
of all species by the end of this century. Are we living in what is called
the “Sixth Extinction”? How do we know when an important species,
a keystone species, is lost? How do we know
what a keystone species is? There’s still a lot we don’t know
about the mechanisms of mass extinctions, letting alone the biological
life on this planet. But we do know
that diversity is declining. We know that from fossil records,
narratives of early explorers, and believe it or not, chefs, who are really good at record keeping, letting us know what was served
at palaces, in monasteries, and on ocean crossing ships. But how many of the species
we know to exist right now will leave fossilized remains
for future scientists? How many of them were recorded
because of commercial, medical, or culinary interests? Throughout history, we only know
about the loss of a species if it was important to us,
one way or another. That is to say, if it was big or tasty. But … (Laughter) But what about the tiny,
inedible creatures? What has happened to them
over the millennia? Let’s look at the oceans, home to over 200,000 named species. Yet, scientists estimate that only 30% of creatures out there
have even been named and classified. That means that 70% of life in the oceans is “unknown” to science. Just last year, researchers discovered
several new species of invertebrates in the deep Pacific Ocean, which they named after
Game of Thrones characters. (Laughter) In 2016, a new species of whale
was discovered in the north Pacific … a whale! How many more undiscovered
species are out there, what are their roles in the ecosystem, and, how many have we lost
before we could find them? And in order to more efficiently
protect our ecosystems, we need to look at their inhabitants and learn how they
are connected to each other. Nobody is an island, and that is especially true
for marine animals. We can tackle that
by looking at food webs. Food webs are systems that connect
small animals to big animals, surface species to deep sea species, land creatures to ocean creatures. Everybody eats, and most species eat in a specific way. They occupy a trophic niche,
a certain place in a food web. Imagine walking down Commercial Street, here in Provincetown, looking for a place to get dinner. You know what you want, and several places offer just that, but each restaurant
has a different vibe to it. You are an omnivore;
you have several choices. Your niche is big. But then your friend speaks up and says, “I’m vegan and gluten-free.” (Laughter) And just like that, your choices are limited
to one or two places. Your friend is a highly
specialized consumer. Her niche is very small. Now, imagine instead of summer, the height of our tourist season, it’s January and only a handful
of places are open. What would you do? Your friend would probably go hungry
or have to cook at home, but you could eat out. As an omnivore, you have options. And, this is how food webs work. Specialists, like your vegan friend, thrive when their
food source is plentiful, and then either move away or die
when their food source is scarce. (Laughter) (Applause) Omnivores usually do well, no matter what. Now, it’s fairly easy
to trace food webs on land. Scientists can observe
their study subjects in the wild. They can even provide them
with different choices of food and see what they pick. When talking about marine food webs,
things get a little more challenging. So instead of direct observation, we employ what is called
“stable isotope analysis” to trace food webs. Now, let’s take the long way round
to explain what that is. As Carl Sagan so eloquently put it,
“We are all made of star stuff.” And he was right. Because nature is really,
really good at recycling. The star stuff he speaks of
is made up of by atoms, just like every single thing
we encounter in our daily lives. And those atoms,
the ones that built you and me, were formed in the Big Bang
and are constantly being recycled. Not only are we made of star stuff,
we are also what we eat. Chances are you’re part dinosaur, Cleopatra, and the clam chowder you had last week. (Laughter) And we can trace that. Almost all elements we know of:
hydrogen, carbon, oxygen, and the whole lot,
have multiple forms … small variables like identical twins, similar, but not exactly the same, called stable isotopes. We can trace food sources
by analyzing stable isotopes in tissues such as hair, scales, skins or bones. Now don’t worry. I’m not going to get into any detail about the fascinating
and exhilarating world that is stable isotope analysis. (Laughter) We have more pressing issues at hand, like, how to use food web science
to streamline conservation efforts. Knowing what animals eat
in the wild is important. It tells us of their place
in the ecosystem. Knowing that, we can better predict
their chances of survival. Imagine the demise of our vegan friends because of a sudden shortage
of fruits and veggies. (Laughter) In my PhD research, I focused on food webs
in seagrass meadows. Seagrasses, like the eelgrass
here on Cape Cod, are important ecosystems. They provide hiding spots
and cover for juvenile animals. Small species
can find shelter there, too. Therefore, seagrass beds
usually boast of a high species diversity. Most of those species are invertebrates
like crabs, worms, amphipods or clams. In my research, I focus on invertebrates because they are important food sources for fish and larger animals
that are commercially important to us. What I found was a very big
and intricate food web in which almost every species
was connected to every other species. How? They eat each other. It was complicated, and it still is. So, I decided to find
the common denominator in this eelgrass bed, the one thing that connects
to everything else. That species or group
of species, in ecology, is called the keystone species. In architecture, the keystone
is at the apex of an archway. It’s the one stone that, if taken away,
would cause cathedrals to crumble. Have you ever played Jenga? It’s that last block
that you had better left alone. And I found it!
. In this eelgrass bed, the keystone species
was an amphipod, or side swimmer, a small invertebrate,
the size of long-grained rice. Now, there may be three people
in this auditorium who have heard of amphipods before. And they are probably people I work with. (Laughter) (Applause) That is because amphipods
are not something we usually pay attention to. They are small, smaller than half an inch. They hide in aquatic
vegetation or sediment, and they are of no direct
commercial interest at all. But there are more than
9,900 species of amphipods. They live in salt water.
They live in fresh water. They can even venture onto land. They live in every ocean.
They are everywhere. Amphipods are important food sources
for fish and larger animals and keep algal growth
and biofilms under control by their grazing. Models showed that
if these creatures were absent, fish might not find enough food
and would move away; algae would start growing uncontrolled,
causing algae blooms. This tiny little critter was, unknowingly,
in control of its entire world. (Laughter) It was the make-or-break component
of the food web I was looking at. Now, I also learned that every food web
can have a different keystone species. So, I set out to determine
as many keystone species as I could, and I’m still at it, collecting animals, analyzing
their stable isotope composition, and figuring out
how they are all connected. Think social media. You are connected to people
you’ve never even met, and I’m sure one of them
is an over-sharer. (Laughter) Now, you might not know them, but you would notice
if they stopped posting, (Laughter) if they disappeared. Now, I also learned that almost anything
can act as a keystone species, depending on the ecosystem
you’re looking at. What they usually have in common is that they are small,
inconspicuous, and not cute. (Laughter) That is why I have made it my mission
to spread the word on keystone species, on invertebrates, on amphipods, on the creatures we share the ocean with and depend on to provide us
with healthy ecosystems. We need them, but we don’t see them. Now, it’s not always possible
to “protect” a keystone species. Look at this critter.
It’s not even a quarter of an inch long. There’s no way you can protect that
without accidentally stepping on it. But here’s what I think: We most certainly can protect its habitat, the area where it lives. Does it need seagrass to survive? Let’s protect and restore seagrass beds. Does is need mangroves? Let’s protect the mangroves. Us humans, we usually tend
to identify with our own kind, with mammals. Don’t get me wrong, my dog
is the most adorable living thing. Audience: Aww … (Applause) And she deserves my complete attention. But if we take, say, 5% of the billions and billions
of dollars that are invested in the conservation effort
directed at cute and majestic mammals and focused it on not-so-cute
and sometimes slimy invertebrates, not only would we be able
to save that one species, but all the other species of clams,
crabs, shrimps, snails, amphipods, worms, urchins, sea cucumbers,
fish, seagrass, mangroves, and horseshoe crabs that are part
of its food web and depend on it. Not only would the invertebrates benefit, the cute and majestic mammals, and ultimately, humanity,
would benefit, as well, because we all depend
on healthy ecosystems. And to keep our ecosystems healthy and help the ones
that aren’t doing so well, we need to start
with the little things in a big way. Imagine protecting and saving
an entire ecosystem by protecting a tiny little amphipod. Thank you. (Applause) (Cheering)

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