Biology Shanty

Uploaded by umncbs on 03.02.2009

DANIEL NIDZGORSKI: Go ahead and pull the net up.
BOY: Whoa, something's heavy.
Something is pretty heavy.
DANIEL: Let's take a look at what you've got.
BOY: What's inside of there, I wonder.
DANIEL: Open it up and see. Larger stuff
like some of the plant pieces get caught in here.
There's a little bit of plant parts and ice.
Take a look in the bottle.
BOY: Whoa!
DANIEL: Those are some of the animals
that live in the lake during the winter.
They're the zooplankton that fish eat.
I'm Daniel Nidzgorski.
I'm a first-year Ph.D. student in
Ecology, Evolution and Behavior in the
College of Biological Sciences.
I study nutrient cycling: nitrogen and phosphorous
and that's a lot of what feeds a lake.
My work is more on the land, so it's the upstream parts
that feed into a lake and drive a lot of the plant growth
that we see that feeds the animals and fish in a lake.
It's my first year with the Art Shanty Project.
I think it's a really great way to introduce people
to a lot of different things.
Folks come in and they don't think there's anything
living under the ice this time of year.
It's a whole world that they never realized before.
We've had some kids come in and tell us this was the
first time they've ever even used a microscope. So what
temperature are we getting right up here near the surface?
BOY: About 50 and going down.
DANIEL: And that's point 50,
so about half a degree above freezing.
EMILY MOHL: So it's pretty cold up there, huh?
BOY: About half a degree above freezing.
DANIEL: Let's go ahead and drop it all the way down
to the bottom, about four feet down.
BOY: It's getting a lot warmer. It's going way up.
So, a full degree now.
EMILY: At least a full degree at the bottom of the lake.
So is that what we expected?
BOY: Nope.
EMILY: No, it's the opposite of what we expected.
BOY: So there's probably going to be more stuff
at the bottom of the lake.
DANIEL: One of the really interesting things about water
is that when it freezes, it actually gets bigger.
So, ice floats.
As the water expands out into the crystalline structure
of ice it is less dense so it floats up.
Even when water hasn't quite frozen into ice yet,
as it's starting to get towards that freezing point,
it's already forcing itself bigger and bigger
into the crystalline structure.
So cold water will actually rise
to the top of the lake when it's freezing.
That means that lakes freeze from the top down instead
of the bottom up. Right now we've got three feet of ice
on the lake but there's still a foot of water below that.
That's where all of the fish,
all of the zooplankton hang out for the winter.
If the lake froze from the bottom up,
then it would get frozen all the way through and
nothing would be able to live through the winter.
That's one of the really unique properties about water,
that actually makes life on earth possible -
is that ice floats.