Transcript

Cynthia Sandeno – Hoosier National Forest

The Hoosier National Forest is in southern Indiana. It's probably one of the smallest national forests in the United States. And it's just in a huge karst region. So you have tons of sinkholes. You have lots of caves and sinking streams. And cave environments are completely dependent on sources that are coming in from the surface for all the organisms that live in there.

One of our missions is to maintain viable populations of native species and caves are certainly linked to that mission. There are lots of species in caves that we know about, certainly there are a lot that we don't know about. If we don't do things to protect and to conserve that resource, you're going to loose it.

Well, I think a lot of the reasons why people are so interested in caves are they're kind of the last unexplored area. Even on the Hoosier in the last couple of years, we've been doing bio-inventories to find out what we have in our caves and we found over 30 new species to science. So as a wildlife biologist, to me the most interesting thing is the fauna. I mean, you find all of these very bizarre creatures that have these adaptations to live in the dark. And if you look in caves, I mean, there are so many species that you really only have found a handful of specimens or one single individual. So to me, cave species don't get the same rating as some of these other species that people are more familiar with. It's hard to, to really get the public enthusiastic about a millipede. And so that's really where it becomes important to start educating people about these species and why they're important. And get them excited about them as well.

Julian Lewis, PhD. – Cave biologist

The southern Indiana area is interesting from a cave biology standpoint because of the effect of the Ice Age glaciers. With each wave of glaciation, you had bands of fauna that both came from the north and came from the tops of the Appalachian Mountains and dispersed widely over the eastern United States.

Indiana is right on the very edge of the Pleistocene glaciation. At the time that the glaciers receded, these animals had a crisis to deal with, they had to do something to find a suitable habitat. One possibility is to go back to a high elevation. Another possibility is to migrate along with the glaciers as they receded. Another possibility was to find a cool, moist habitat in the area to which they had come. And that in Indiana would be a cave.

The Hoosier National Forest takes in a broad swath of the Indiana karst. It has small areas where you'll have a band of caves formed in limestone separated by non-limestone ridges and you have intense speciation occurring in these karst islands. And so, you get a very large number of endemic species. The entire cave systems here and its fauna is a laboratory of evolution.

Jean Krejca, PhD. – Cave biologist

Caves are really good places to study evolutionary biology because they are limited environments. There are several different levels of cave adaptation is how we describe cave ecology. And one level for example might be a trogloxene. That will go and use the cave for part of the time but then come back out to the surface. It can't spend its entire life cycle in a cave.

And then the next level up of cave adaptation is a troglophile. And troglophiles can spend their whole life in a cave, for example a cave salamander, but they don't need to spend their life in a cave. In other words, they could also live under rotting logs or under rocks on the surface just in places that are dark and humid and cool.

And then of course the highest level of cave adaptation is troglobite. And troglobites are fully cave-adapted organisms. They cannot survive outside of the cave; they're obligatory to be in the cave. And those are the ones that we think of as the typical really extreme cave livers. They have, a lot of times, no eyes left at all and no pigment and they tend to have really slowed down life history strategies.

Cave adaptation can happen really quickly, remarkably quickly. When there are species like the sculpin they go quite a ways back into the cave but they're not cave adapted species. They're not troglobites. They're trogloxenes or troglophiles. The difference between those two ecologic classifications are that trogloxenes have to leave the cave at some point to complete their entire life cycle. For example, they might have to leave the cave to breed or to find food. And then they can come back in the cave and just use it for shelter. But these sculpins are probably spending their entire life cycle in the cave because of how far back into the cave they are. And a small little fish like a sculpin isn't going to swim for two miles just to go outside to find a meal. It's undoubtedly eating inside the cave. And also because of the very small individuals we've seen very far back into the cave, it's very good evidence that they're reproducing in the cave. So that actually means that they're crossing the boundary between just being a trogloxene that occasionally goes in the cave to being a troglophile that can spend its entire life cycle in a cave. From an evolutionary standpoint, that's an interesting place to be in where you're kind of at the cusp of becoming adapted to living in a cave.

For an organism to become cave adapted, first it tends to loose some of the characteristics that we associate with being on the surface –- for example, eyesight and pigment. But at the same time it's gaining other senses that make up for the eyesight and once it becomes adapted to the cave environment, it's unlikely to turn around and come back out the other direction.

William Pearson, PhD. – University of Louisville

What I like about cave fishes are their adaptations. And how they've changed through time to become adapted to the underground environment. They're definitely case selected animals meaning that they live a long time. They don't reproduce very much. They live in a fairly protected environment. They don't have any natural predators. They are the top carnivore of their system. And so they're sort of like the little tigers of the streams in caves.

And they live to be for sure 30 years old and might live to be 60 or 70 years old. They are blind; of course that doesn't hurt them in the cave. Well, there are eye sockets in the skull that are still there, apparently hard to change the shape of your bones relative to the shape of your soft body parts through evolutionary time. But it may look like it's regressing to us but the loss of a functioning organ like an eye is really not anything more than evolution to meet a different environment. And so, it's really just evolution in a different direction.

Climatic change is one reason that is usually given for organisms going underground and pre-adaptation. If you're pre-adapted for living in a cave, that means you, you already lived in a dark place somewhere, maybe under leaf litter or maybe in organic debris on the bottom of marshes and swamps.

Why would you go underground? Well, you might go underground if the climate is getting warmer and you're a cold adapted fish. You could get cooler waters by going underground. You might go underground if there were predation pressures above ground and you slip into a cave—there's nobody to eat you. Those are all thought of as possible explanations for why cave fishes went underground in the first place. Or their ancestors did I should say.

The range of the Northern Cave fish is, is fairly small, maybe 110 miles by 20 miles wide of kind of a little ellipse that runs from Mammoth Cave in the south, in Kentucky, all the way up to just south of Bloomington in Indiana. And that's a fairly small range for a fresh water fish I would say.

They are vulnerable, there's no doubt about that. Their populations are concentrated in about five or six or seven real population centers. And a spill could wipe out one tenth of the population real easily. They need to be watched to make sure that we haven't lost an important population here and then an important population there. And if that does happen, then they would need more protection in their remaining meta-populations.

Horton Hobbs, PhD. – Wittenburg University

Crayfish are an old group. They've been around a long time. And one that has, pretty much, no eyes is an obligate, highly specialized organism. There are around 41, 42 species of blind, white crayfishes. They may look very spindly and very dainty and, and weak, but in reality these things are pretty tough. Out here the local streams will have crayfishes that live two and a half to three years maximum, that's their life history. But blind crayfishes kick it up to 50, 60, 70 years, or more. I think it's part of the adaptations that, you know, we think of some of these very elaborate traits that we begin to see appearing in obligate organisms, some of which include longevity. But loss of eyes, loss of pigments, those are really sort of characteristic things that occur across these major groups of organisms. So it's in response to moving underground into that type of environment.

To see an organism that has given up so much to live in this environment and altered everything that we think of as a classic surface form to show some of these derived traits that they have, that are so different from the surface things. And how they modify their life history. It's sort of this channeling of the speleo-environment that you end up producing organisms that have so many of these similar sorts of traits and I think a lot of it can be certainly traced back to the energetic problem.

You're looking at an environment that has limited energy. They have to make a little bit of food go a long way and anything organic. And so what we're talking about primarily in these caves would be leaves and sticks and acorns and walnuts and things like that. And they're getting something from eating that vegetative material, but where they're really gaining their energetic kick is from the microbial community. And it's sort of like the analogy of having a saltine cracker and you eat that and you get a little something, it tastes okay, and you get a little kick from it. But if you take a big slab of peanut butter and you go across it, and eat it then you're really getting the energy. You're really getting something for the effort. And in essence that's what happens. The microbial community that begins to coat and break down organic materials, that's the peanut butter and that's where they're getting the, the real kick.

Hazel Barton, PhD. – Northern Kentucky University

The majority of life on earth on the surface is driven by sunlight energy. And obviously in a cave you don't have that. So you lack one of the big energy drivers of an ecosystem.

So it becomes a very starved environment. For example if you took a grain of sugar and broke it up into a thousand parts and took one of those parts and put it in a liter of water, that's about how much energy is available for microorganisms in these environments.

When people think about a starved environment, they might think of something like the desert where there are very few species because there's just not enough energy to support the growth or life of these microorganisms. And that's what we expected to find in caves. But what we see is that that's true when you go into a system, as you get further away from the energy input at the entrance, you see a drop off in the number of species. But there is a threshold when all of a sudden you start to see the number of species and the diversity increase. And we think what's happening in these cave systems is that they've become so starved that there's a mutualism and that everybody kind of works together. And when you have them all work together, one organism brings in the energy, which drives another organism to bring in the nutrients which allows another organism to create the building blocks and the energy and the sugar for other organisms to grow. So you have this mutualistic interaction. And as a result, you have to have many species working together within the ecosystem to promote this, this life under extreme starvation. So we think that, you know, you've gone passed that analogy with the desert, you're way, way many orders of magnitude more starved than that. And when you get down to that extremely low level, you actually see the diversity start to rise again.

Microbes are so small that they can actually swim over time through the rock itself. When you think about, you know, a crawfish in a cave in Indiana, it may be confined to that cave its entire life because it can't move. Where the microbes can, you know, worm their way through a cave and pop up in another cave somewhere else because over geologic time, they've traversed that rock.

The other thing that microbes do is they're light enough they can actually float in air currents. So when a cave breathes out and blows air into the environment, the microbes can you know float around in the air and then get sucked into a cave somewhere else and then they flourish in that cave.

So every environment that we look at the microorganisms are the basis of all the ecosystems that form around them. So in caves, you know, they're responsible for mobilizing a lot of nutrients that you find in cave environments. When detritus gets washed in by floods, they're breaking it down and releasing energy for it. So they actually form the basis for nearly all the ecosystems that you will find in a cave.

Horton Hobbs

In terms of just what's up above and how that's having some interaction with what's below, the type of vegetation will certainly affect what's down below. So in Indiana this is sort of a temperate latitude and so we know we're going to have deciduous input every fall. And you're going to see a lot of organic input from those deciduous trees that drop their, their biomass during the fall. And that gets flushed in. That gets enriched in the peanut butter and the cracker analogy that we talked about. All of those things are gonna help feed that system.

So there's certainly gonna be differences of pine forest versus an oak hickory forest would be quite different in the volume, the type of food that would ultimately make its way into the cave.

Certainly caves are, are very closely linked to the surface. Without the surface feeding that cave system, nothing is going to exist, not very long any way. And certainly some species that are obligate forms, that never leave the cave, it's absolutely critical. Now when you start thinking about bats that fly out and feed and then come back, but their life histories are still tied to it. There's certainly species that will use caves during the summer, breeding, you know, raising their pups and those kinds of things, that occurs in caves for some species. And so that becomes critical to those species that really are not true cave dwellers in the sense that they spend their whole life there. But yet they're utilizing it. So it's a very tight link to them.

John Whitaker, PhD. – Indiana State University

Bats are mammals. They have hair, feed their young milk. But they're the only mammals that fly. That's what distinguishes them from everything else.

There are some bats going way back in the fossil record. But the earliest fossil bats are well-formed bats. So from the fossil record we really can't tell anything about their evolution. However, from their structure, most people would think that they're probably from the shrew type ancestry.

It's the colonial bats that are in caves. Exactly why they hang upside down we're not quite sure. This is one of the things that gets them up high. Hanging upside down allows them to just drop and then fly out. Also if there's something below them, a predator below them, they're in position so they can see something below them and they wake up very fast. Most hibernators wake up slowly.

In the fall, bats come into these cave and mine entrances in large numbers and we said they swarm. They come in and out at night and we think mostly what they do is pick up mates. They may also be on migratory routes. We've been studying these populations for a long time trying to determine where they come from, where they go, when they come, when they go and that sort of thing and at what time of the year, the differences between the species. We know really very little about them.

Just recently we've been able to put radios on them. We could follow these little radio and track the bats in flight to see where they're feeding. They eat loads and loads of farm pests. The big brown bat, about 80% of its food are farm pest insects. That's one of the reasons they are so valuable to us. Another thing, they are about the only predator around here that feeds on night flying insects. So this helps to keep the balance of nature. Something's got to feed on those things and it happens to be bats.

Some of the bats make their summer colonies under sloughing bark of pretty much dead trees. So there's six species that have to have trees, have to have at least limited forest.

Well, the biggest thing we can do for bats and for most other species is to set aside more land. A little piece of forest will do fine. Most bats don't feed too much way back in the forest; many of them feed along the edge of forest. We're loosing about 101,000 acres per year to development. A lot of it is forest. We've got to stop doing that.

Bats live a long, long time. The record that I know of in the Little Brown bat is 34 years. That's just phenomenal for an animal that size. A mouse or a shrew will live less than a year lots of times. Every species of bat that we have has a different life history, quite major differences. Most of them, all but three, kind of all look alike.

“So what do you got?

It looks like a red bat.”

One is red, one is kind of a hoary color, it's called a hoary bat. It looks like it has hoar frost on it. And the third is the silver haired bat which is really dark chocolaty brown or almost black. The rest are pretty much brown bats. There's some difference-- some of them in the teeth, there's some small differences in ears, the length of the ears. No other mammal flies around. Very few animals have echolocation. They are just plain darn interesting animals.

Tim Carter, PhD. – Ball State University

The Indiana bat is a federally endangered species. Currently there's somewhere around 400,000 animals left. In the 1960's there were over 880,000. So we've lost half the population.

The Indiana bat uses caves or mines during the winter months for hibernation. Then during the summer months they leave those caves or mines and they head out into the forest.

When I started there were lots of holes in the natural history of the Indiana bat that we just frankly did not know. We didn't know much about where they foraged. We didn't know a whole lot about where they roost in the summertime. We don't know much about where they eat. Those kinds of simple questions which you'd be surprised.

“Got another one.”

“Oh good.”

Everybody thinks we know a lot about all the wildlife and there's quite a few animals especially the bats that we know very little about. And it's very hard to manage a forest and to try to save this endangered species when you don't even know what it eats. And that's one of the things that's really difficult. You've got a nocturnal animal that flies exceptionally fast and covers large areas. And they're very hard to monitor. They're very hard to, to try and census and get an idea of how many animals are we looking at.

“And this is a male.”

“Ok.”

“Juvenile.”

So just trying to figure out how many Indiana bats there are here is very difficult. And that's one of the aspects of this project here in Camp Atterbury that we've been working on: is trying to figure out a way to, to estimate the populations.

“3 and a half.”

“Ok I'm letting him go.”

We're experimenting with a relatively new technology called PIT tags. It's a tiny passive integrated transponder, which is what PIT tag stands for, that you inject under the skin. And then when you pass a reader over it, it works kind of like a bar code at a grocery store. When you pass the reader over it, it will activate that little chip which transmits a unique signal and you get a number back. And you can say “okay this is bat number” and you've got this big, long, ten-digit number.

So there's potential for maybe finding these guys in the hibernacula and starting to figure out where their summer grounds are versus their winter grounds. There's potential for maybe finding them during migration. So there's lots of potential for this kind of marking technique. And then hopefully once we've done that and accomplished that we can really start to figure out what practices as land managers are helping and hurting these animals. Does it matter if we timber harvest? Or you know is that really bad for the animals? At this point, we're just making guesses. We really don't know and it'd be really good to pin that down and say yes this is good for them and no this is bad for them.

Julian Lewis

When you look at caves and karst and ground water, what you have is, in fact, not just a tube if you will that has bugs and worms and bats and salamanders and fish and things in it. It is a small cross section of a much larger environment. The trees that live on the surface are as much a part of the cave environment as the cave itself.

Karst in Indiana is under a full force attack as humans encroach more and more on the natural environment. There's still a wide held belief that you can throw your pesticide in the sinkhole and that's the last you'll see of it. That's not the case. It will come back to bite you one way or another.

Pseudo scorpions aren't good to eat. They don't cost anything. No one will ever get rich on finding pseudo scorpions, but they're a small part of a much larger animal spectrum that, when you pull on any part of a food web, the whole thing's likely to go kaflooy. It's difficult to make a case for the importance of a springtail but it's not difficult to make a case for the land management that goes into keeping the karst environment intact. And the indicator of that is: are the bugs and worms intact?

Horton Hobbs

I think it's critically important that we understand karst a lot better than we do. It's important that we learn more about the organisms that are there because those organisms are going to tell us what's going on in that water. What's going on in that whole system. Even though you may not care about some little micro crustacean who's crawling around in a cave or micro arthropod of some type, that's just part of the whole biodiversity of this planet. And certainly Southern Indiana is a pretty rich biodiverse part of karst. And if you start little bit by little bit peeling it away, then sooner or later things are going to turn around and bite you, big time. (Laughs)

Caves: Life Beneath the Forest

Produced by:

Ravenswood Media, Inc.

Funded by:

Hoosier National Forest

Indiana Karst Conservancy

National Speleological Society

Director/Cinematography:

David McGowan

Second Camera/Sound:

Jacek Lupina

Coulter Mitchell

Suzie Crombie

Keith Pamper

Production Manager:

Kriste Lindberg

Original Music:

Bahman Saless

Opening/Credits Music:

Saint-Saens

"Carnival of the Animals-Aquarium"

Editors:

Suzie Crombie

Coulter Mitchell

David McGowan

Web design:

Mike Brockway

Interviewees:

Cindy Sandeno

Julian Lewis

Jean Krejca

William Pearson

Horton Hobbs

Hazel Barton

John Whitaker

Tim Carter

Volunteers:

John Benton

Dave Black

Ronnie Burns

George Cesnik

Bud Dillon

Keith Dunlap

Dave Everton

Brant Fisher

Don Ingle

Keith Pamper

Chris Parks

Patty Ruback

Bob Sergesketter

Mark Sparks

Bob Vandeventer

Richard Venier

Sue Vernier

Steve Weinzapfel

Molly Wright

Consultants:

Virgil Brack

Scott Johnson - Indiana DNR

Andrew King - USFWS

Tom Simon - USFWS

Special Thanks:

Bud Dillon

Marc Hancock

Richard Jones

Bill Schaefer

Bluesprings Caverns

Camp Atterbury

Cave River Valley Recreation Area

Crest Motel

Harrison Crawford State Forest

Indiana Department of Natural Resources

Paoli Golf Course

Spring Mill State Park

US Fish and Wildlife

Video clips at www.cavebiota.com

 

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