for the past 12 weeks we've been
investigating our living planet together
learning how it works on many levels how
populations of organisms interact how
communities thrive and ecosystems change
and how humans are wrecking the nice
perfectly functioning systems earth has
been using for hundreds of thousands of
years and now it's graduation day this
here is like the commencement speech
where i talk to you about the future and
our role in it and how what we're doing
to the planet is totally awful but we're
taking steps to undo some of the damage
that we've done so what better way to
wrap up our series on ecology than by
taking a look at the growing fields of
conservation biology and restoration
ecology these disciplines use all the
kung fu moves that we've learned about
in the past 11 weeks and apply them to
protecting ecosystems and cleaning up
the messes that we've already made and
one of the main things they teach us is
that doing these things is difficult
like in the way that uncooking bacon is
difficult so let's look at what we're
doing and try to uncook this
unbelievably large pile of bacon we've
made
[Music]
just outside of missoula montana where i
live we've got a superfund site not
super fun super fund a hazardous waste
site that the government is in charge of
cleaning up the mess here was made more
than a hundred years ago when there was
a dam in the clarkvark river behind me
called the milltown dam this part of
montana has a long history of copper
mining and back in 1908 there was a
humongous flood that washed about 4.5
million cubic meters of mine tailings
chock full of arsenic and toxic heavy
metals into the clark fork river and
most of it washed into the reservoir
created by the milltown dam i mean
actually it was lucky that the dam was
there it had only been completed six
months before or the whole river system
all the way to the pacific ocean would
have been a toxic mess as it happened
though only about 160 kilometers of the
river was all toxic messed up a lot of
it recuperated over time but all that
nasty hazardous waste was still sitting
behind milltown dam and some of it
leached into the groundwater that
started polluting nearby residents wells
so scientists spent decades studying the
extent of the damage caused by the waste
and coming up with ways to fix it and
from 2006 to 2010 engineers carefully
removed all the toxic sediment as well
as the dam itself now this stretch of
the clark fork river runs unimpeded for
the first time in over a century and the
restored area where the dam used to be
is being turned into a state park
efforts like this show us conservation
biology and restoration ecology in
action conservation biology involves
measuring the biodiversity of an
ecosystem and determining how to protect
it in this case it was used to size up
the health of fish populations in the
clark fork river which were severely
affected by the waste behind the dam and
the dam blocking their access to
spawning grounds upstream and figuring
out how to protect them during the dam's
removal restoration ecology meanwhile is
the science of restoring broken
ecosystems like taking an interrupted
polluted river and turning it into what
you see taking shape here these
do-gooder fix it up sciences are
practical rather than theoretical by
which i mean in order to fix something
that's broken you've got to have a good
idea of what's making it work to begin
with if something was wrong with the
expansion of the universe we wouldn't be
able to fix it because we have no idea
at all what's making all that happen so
in order to fix a failing ecosystem you
have to figure out what was holding it
together in the first place and the glue
that holds every ecosystem together is
biodiversity but then of course
biodiversity can mean many different
things so far we've generally used it to
mean species diversity or the variety of
species in an ecosystem but there are
also other ways of talking about
biodiversity that help conservation
biologists and restoration ecologists
figure out how to save species and
repair ecosystems in addition to the
diversity of species ecologists look at
genetic diversity within the species as
a whole and between populations genetic
diversity is important because it makes
evolution possible by allowing a species
to adapt to new situations like disease
and climate change and then another
level of biodiversity has to do with
ecosystem diversity or the variety of
different ecosystems within an area a
big old forest for example can host
several different kinds of ecosystems
like wetland alpine and aquatic ones
just like we talked about when we
covered ecological succession the more
little pockets you've got performing
different functions the more resilient
the region will be as a whole so yeah
understanding all this is really
important to figuring out how to repair
an ecosystem that is in shambles but how
do conservation biologists take the
information about what makes an
ecosystem tick and use it to save the
place from going under well there's more
than one way to approach this problem
one way is called small population
conservation this approach focuses on
identifying species and populations that
are really small and tries to help boost
their numbers and genetic diversity low
population and low genetic diversity are
kind of a death knell for a species they
actually feed off each other one problem
making the other problem worse
ultimately causing a species to spiral
into extinction see when a tiny little
population suffers from inbreeding or
genetic drift that is a shift in its
overall genetic makeup this leads to
even less diversity which in turn causes
lower reproduction rates and higher
mortality rates which makes the
population smaller still this terrible
little dynamic is known by the awesome
term extinction vortex the next step is
to figure out how small a population is
too small ecologists do this by
calculating what's called the minimum
viable population which is the smallest
size at which a population can survive
and sustain itself to get at this number
you have to know the real breeding
population of say grizzly bears in
yellowstone national park and then you
figure out everything you can about a
grizzly's life history how long they
live who gets to breed the most how
often they can have babies that kind of
thing after all that information is
collected ecologists can run the numbers
and figure out that for the grizzlies in
yellowstone a population of say
hypothetically 90 bears would have about
a 95 chance of surviving for a hundred
years but if there were a population of
100 bears the population would likely be
able to survive for 200 years something
to note ecology involves a lot of math
so if you're interested in this that's
just the way it is so that's the small
population approach to conservation
another way of preserving biodiversity
focuses on populations whose numbers are
in decline no matter how large the
original population was this is known as
declining population conservation and it
involves answering a series of related
questions that get at the root of what's
causing an organism's numbers to
nosedive first you have to determine
whether the population's actually
declining then you have to figure out
how big the population historically was
and what its requirements were and
finally you have to get at what's
causing the decline and figure out how
to address it milton dam actually gives
us a good example of this process in the
winter of 1996 authorities had to
release some of the water behind the dam
as an emergency measure because of a big
ice flow in the river that was
threatening to break the dam but when
they release the water a bunch of toxic
sediment went with it which raised the
copper concentrations down river to
almost 43 times what state standards
allowed as a result it's estimated about
half of the fish downstream died half of
the fish dead and researchers have been
monitoring the decline in populations
ever since this information was really
helpful in determining what to do with
the dam because we knew what the fish
population was like before and after the
release of the sediment it was decided
that it would be best to get the dam out
as soon as possible rather than risk
another 1996 scenario which brings me to
the place where conservation biology and
restoration ecology intersect
restoration ecology is kind of where the
rubber meets the road in conservation
biology it comes up with possible
solutions for ecological problems now
sort of a time machine which i'm working
on you can't really get a natural
environment exactly the way that it used
to be but you can at least get rid of
whatever's causing the problem and help
recreate some of the elements that the
ecosystem needs to function properly all
of this involves a whole suite of
strategies for instance what's happening
in milltown is an example of structural
restoration basically the removal and
cleanup of whatever human impact was
causing the problem in this case the dam
and the toxic sediments behind it and
then the rebuilding of the historical
natural structure here the meanders of
the river channel and the vegetation
another strategy is bioremediation which
recruits organisms temporarily to help
remove toxins like bacteria that eat
wastes or plants that leech out metals
from tainted soils some kinds of fungi
and bacteria are even being explored as
ways to bile remediate oil spills yet
another somewhat more invasive
restoration method is biological
augmentation rather than removing
harmful substances this involves adding
organisms to the ecosystem to restore
materials that are gone plants that help
fix nitrogen like beans acacia trees and
lupine are often used to replenish
nitrogen in soils that have been damaged
by things like mining or over farming
and ecologists sometimes add mycorrhizal
fungi to help new plantings like native
grass take hold but of course we're just
humans and we're not as smart as
millions of years of evolution sometimes
we get things wrong for example when you
bring an invasive species into a place
to eradicate another invasive species
sometimes you just end up with two
invasive species on your hands which
collapses the ecosystem even more
rapidly the introduction of cane toads
to australia in the 1930s to control
beetles is a particularly infamous
example not only are they everywhere now
but because they're toxic they're
poisoning native species like dingos to
try to eat them nice so you know what i
have an idea after spending the past
couple of weeks talking about ecological
problems i've come to the conclusion
that it's just easier to protect
ecosystems rather than trying to fix
them because we know a lot about what
makes ecosystems tick so if we spend
more time trying to save them from us
and our stuff we'll spend less time
cleaning up after ourselves and running
the risks of getting it wrong because as
we all know the sad fact is uncooking
bacon is impossible but we can't eat it
thank you for joining me on this quick
three-month jaunt through the natural
world i hope it made you smarter not
just in terms of passing your exams but
also in terms of being a homo sapien
that inhabits this planet more wisely
and thank you to everyone who helped us
put these episodes together our
technical director nick jenkins our
editor caitlin hoffmeister our writers
blake d pastino jeslin shields and
myself our sound designer michael aranda
and our animators and designers peter
winkler and amber bushnell and the good
news is there's more crash course coming
at you soon if you have any questions or
comments or ideas we're on facebook and
twitter and of course down in the
comments below we'll see you next time
you