(wilderness sounds)
(lighthearted instrumental music)
- [Voiceover] Big South Fork National River
and Recreation Area
and Obed Wild and Scenic River are two of the
very few remaining rivers in the region that are protected.
- [Voiceover] The Big South Fork is one of the crown jewels
in the Cumberland River System.
It is one of the last places in which you can still find
some of our most rare species.
- There are over 50 mussel species
and probably 25% of them are federally endangered.
- This is Epioblasma brevidens, the Cumberland combshell,
a federally endangered species.
Big South Fork is one of the
last great places this animal occurs.
- [Voiceover] Mussels are considered important
because they are, if you will,
the canaries in the coal mine.
They are filter feeders, they don't move,
so whatever comes down the river, in terms
of contamination, they're subjected to,
they cannot avoid it.
So what's being done here is long-term
quantitative monitoring to figure out
what species of mussels are here
and how many.
- The actual process is to
establish a grid in these locations
within those grids we monitor square meter units
and within a sampling frame
we'll count the mussels, identify the species
and measure the mussels
so over time we have a good idea
of how the mussel populations are doing,
how many young ones, middle aged ones,
and old ones are there,
what the structure of the population is.
- These are two individuals, same species,
the individual in my left hand
is perhaps three, four years old.
The individual on my right,
guessed on the number of growth lines,
this thing is quite old.
- It can be very difficult to find mussels
- especially in a cobble gravel environment.
They range in size from the size of your little fingernail
to the size of a small dinner plate. They blend in,
they are partially buried or completely buried,
and so it takes a trained eye to find them sometimes.
- Mussel monitoring involves taking the mussels
out of their habitat in the substrate
and handling them briefly
because there are endangered species involved
we have to have people that have been permitted
by the U.S. Fish and Wildlife Service.
We place them back in the substrate
as close to the original orientation as we can.
Out of an abundance of caution,
we don't do this monitoring often.
We only do it infrequently, every three years.
- Of the 300 species of freshwater mussels in North America,
about 70 percent of them are imperiled, they're declining,
or they have disappeared altogether.
It's important to monitor what we have left
because that way we know what's happening in our rivers.
(wilderness sounds)
- [Voiceover] Cobble bars are a unique vegetation community
in the bottom of these steep-walled river gorges
- and they resemble the Western tall grass prairies.
- They have a lot of the same species
- but they have a lot of their own endemic species,
species that don't occur anywhere else in the world.
Unlike the tall grass prairies of the West that
are maintained by wildfire,
these are maintained by the roaring floods
that come down these rivers
and scour everything that's not flood-adapted away.
The plants that are native to the cobble bars
have really deep strong roots, most of their mass,
most of the plants are actually underground,
so if their top parts are scoured away by the floods
they can easily re-grow the top parts.
They include the two main species of tall grass
that are the keystone species in the Western prairies,
big bluestem and Indian grass.
The roots go 15 feet into the ground,
winding their way between the rocks
and holding them solidly there.
And they hold everything in place
against the force of the floods.
It's hard to believe, but sometimes, on this very plot,
right where we're standing,
there is a house-sized pile of woody debris, of logs,
giant logs, trees this big around, that
have just been washed in by the river and all piled up here.
I've seen that pile here 15 to 20 feet high,
right where we're standing.
And then you come back a week later
and another flood has come through
and washed it away.
The point of the long-term monitoring
of the cobble bars that we're doing
is to see if the community is changing.
Most of these species cannot survive in shade,
so if anything happens to cause trees
to advance out over these habitats
that species would completely disappear, they'd be gone.
This is Cumberland rosemary,
it's a federally-listed, threatened plant
and the vast majority of all that remains in the world
is inside the boundaries of Big South Fork National River
and Recreation Area and Obed Wild and Scenic River.
(lighthearted instrumental music)
Some of these cobble bars are pretty challenging,
most of them involve a lot of off-trail work,
a lot of bushwhacking down extremely steep places.
Sometimes it's crawling on hands and knees
hauling a heavy pack, and then,
either swimming or wading the river
to get to where you need to be.
The monitoring that we do has to be something
that can be objectively quantified
and then repeated several years later
and then repeated the same way.
You can walk out on to a cobble bar
and say, “well, it kind of looks different to me”,
but that doesn't count,
you have to have something that you can measure.
And so the way we do that is to pull transect tapes out
across the cobble bar at intervals.
Transects have to be straight,
and so if you're pulling the transect tape
and you see a wall of greenbriar in front of you
and black locust, you can't go around it.
You have to go straight through it,
that tape has to be straight,
and then we use a laser device every half-meter
along that transect to count what we're hitting
in terms of the stony substrate,
the grass that's supposed to be there,
the other herbs that are supposed to be there,
or the woody things that are not supposed to be there.
And we measure the extent of canopy over the line,
over those transect tapes,
by species so that we know whether they
are being invaded by species that are not flood-adapted,
which is a very bad sign,
or whether they are being encroached upon
by species like sycamores and river birches
that are supposed to be there.
(lighthearted instrumental music)
This river system, not just the river itself
and the aquatic creatures, the fish
and the fresh water mussels that live in it,
but everything adjacent to it,
even the forests that come down to the edge of the river,
definitely the cobble bars, all of it is connected.
The other things that we monitor,
the freshwater mussels, the water quality
are very important.
- As a manager of the park,
you can't manage resources without having scientific data.
So the scientific data associated
with the monitoring program,
gives us the ability to understand the natural environment,
the health of the river and its organisms.
- The value of long-term monitoring is
so that we can know what's happening
to the plants and animals and their habitats,
in the time that we can do something about it.
- One never knows what all the connections are,
what it would cost if those species were lost,
if this habitat type were lost.
These things might not still be here
if it weren't for the protection
of the National Park Service.
(lighthearted instrumental music)