Program Two: "Keepers of the Biosphere"

The View from the Forest (Part 4 of 10)

Dr. Dan Janzen and Dr. Ignacio Chapela catalog both the larger and microbial life forms inside a single ecosystem in Costa Rica, finding that neither plants, animals, nor microbes would be able to exist without the others.

 

Transcript

Narrator, Lillian Lehman: In Arizona, in the mid nineteen eighties, some ambitious visionaries built a small version of Earth. A tropical forest, a tiny ocean, streams, grasslands, even a desert, sealed by glass and steel. Eight men and women were to live here, physically isolated from the outside, for two years. Biosphere 2 was a complete world. There were many species of plants and animals. Seven ecological zones. A recipe for life. Their goal was to create a self sustaining living environment. If successful they would prove the possibilities of sustaining life on other planets, such as Mars. In August of nineteen ninety one it was all ready, the eight Biospherians, were about to breath their last breath from the outside world. The concept for the Biosphere life support system was straight forward, total recycling. Everything needed for life, food, oxygen, materials of all kinds. Would be used, and reused. Waste would be recovered and recycled. Biosphere 2, would be completely self contained, with nothing needed from the outside world. The concept is sound. As demonstrated by this unique airtight globe. Called a ecosphere. Inside water, shrimp, algae, and a mix of aquatic bacteria can survive, and thrive for years. Nutrients are used, and reused. Waste from one species is what another needs. In a endless cycle, all the nutrients for all the creatures are provided for. Biosphere 2, set out to do the same on a larger scale. For months all was well, the food consumed, was grown within the biosphere. The biospherians went about their work. All ecological zones flourished. But unexpectedly, oxygen levels began to fall. One species after another began to die. The birds disappeared, then the frogs, the Biospherians found it increasingly hard to breath. {Sound of alarms going off.} Urgant efforts at a remedy failed, and in desperation oxygen was pumped in from outside. The sacred seal was broken. Work inside continued, but the major feature of the grand experiment was gone. Many explanations were proposed for the dramatic loss of oxygen. Plant growth in Biosphere 2, was less abundant then normal, and so oxygen from photosynthesis was less then expected. But this only explained a fraction of the loss. The suspension arose that a major part of the loss was due to the tiniest creatures, that Biosphere 2 had failed in large part because of microbes. The question is why? Through all of nature, microbes govern the cycling, and reuse of nutrients. They are the smallest self contained living creatures, protozoans. Common in pond water, bacteria, viruses, and fungi. An algae like these volvox cells, responsible with many other types of algae and bacteria for half the oxygen world wide, that we humans breath. Microbes populate ever nook and cranny on Earth. A hundred thousand microbes in every drop of water. Scientist now are constantly discovering new kinds, and they think that vastly more are still to be found. The smallest life on Earth, microbes affect the biggest events, holding the keys to life and death, throughout the biosphere. But how could things so small, affect something so large?

{Title: The View from the Forest.}

Narrator, Lillian Lehman: Our first clues can be found here. There are few areas on Earth as complex in their ecology as the rain forest in Costa Rica, and Central America. It is home to some two hundred, and thirty thousand species of plants, animals, and insects. Nearly a hundred times in Biosphere 2. Time and evolution have fine tuned the forest into a almost a perfect recycling machine. And at the heart of this machine, are the microbes. A man who lives to understand the machine, the working of all its parts, is biologist, and ecologist Dan Janzen. Janzen's ambitious goal is a complete species survey, an inventory of all the plants, insects, and animals living the Guanacaste area, of Costa Rica's north west. This formidable goal is based on a simple idea. If you don't know what's there, everything that's there, you can't expect to understand how it all works.

Scientist, Dan Janzen: Each single spices does things to other things. It eats some, and gets eaten by them, it parasitizes them, it sits on them, and does everything to the other guy next door, one way or another. Which then does something to the guy next door, which does something to the guy next door. So they're all connected.

Narrator, Lillian Lehman: Janzen's primary focus as a biologist, is the larger life forms. But as long as can remember, he has viewed microbes as very integral parts of the ecosystem.

Scientist, Dan Janzen: If I want to understand how this eats it, versus how the other one, I know that the microbes are going to come and be a part of that story.

Narrator, Lillian Lehman: Half the year Janzen lives far from this rural life, teaching biology at the University of Pennsylvania. The other six months, he and his wife biologist Winnie Hallwachs live and work in Costa Rica.

{Classical, flute style music.}

Scientist, Winnie Hallwachs: In my day, the biology text books did not have much treatment of microbes. I knew that they were out there, but the sense that they have really structured the world around us. That they are the engineers, that made life livable on planet Earth, and that they are the engineers that maintain conditions within the range that we can survive, that has come to me much more recently.

Narrator, Lillian Lehman: Every creature in the forest environment is making something, using something, transforming something. A single tree may be home to a hundred species of insects, birds, plants, vines, and thousands of species of microbes. There are microbes everywhere. Five thousand species in a tea spoon of soil. Virtually all the recent recycling in the forest is done by microbes. Many of these microbes need, and use oxygen just as we do. And they release carbon in the form of carbon dioxide, just as we exhale. The mold spreading across this tree, is a collection of microbes. Individually microscopic, collectively visible. Fungus, responsible for much of the forest recycling is also formed from billions of fungal cells living together. In one way or another, microbes connect every living thing in this forest, every part of what biologists call the Web of Life.

Scientist, Dan Janzen: The irony is that, if someone says the Web of Life, one has a tendency to two dimensional. A spider web. We tend to build this imaginary structure, and which isn't true. Because of what it really is, is a three dimensional structure and the microbes are all intertwined through all of it. Instead of underneath it. Okay. And as such, I don't think of them as the base, I think of them more as glue, that is sort of sticky everywhere. You know, my hand, has a sheet of microbes. This table, that is a sheet of microbes, this moth, the butterfly, just pinned here, is a sheet of microbes, they're sort of everywhere.

Narrator, Lillian Lehman: A butterfly has its own particular community of microbes. Every living creature has its own microbial group. When life is over, swarms of microbes, especially bacteria, and fungi, move in to complete the cycle of life and death. Only in preparation of course, for new life to come.

Scientist, Dan Janzen: They are eating, and they're chopping it up into pieces and as they do this, they create jillions of little molecules, which then in a variety of ways, the bigger begin to pull back up and make bigger things. Then there's the, microbes chopping them down again. So that cycle is going on all the time.

Narrator, Lillian Lehman: In the forest there are millions of exchanges of nutrients and energy, between hundreds of thousands of species. Every organism gets what it needs, and gives what it doesn't. And in the ecosystem as a whole, the exchanges balance. But in the closed ecosystem of Biosphere 2, that ecolibrium was never achieved, or was lost. Dan Janzen is a pioneer in his field, so is Ignacio Chapela, a microbiologist from the University of California at Berkeley, their professional interests overlap especially with regard to insects.

Scientist, Ignacio Chapela: The first time I became interested in the microbial world, was by dealing with insects. One day I started realizing that there was a lot more behind what I could could see, and the microbial world, was precisely that unknown depth that I was looking for.

Scientist, Dan Janzen: Hi, hola, hola, hola. How are you?

Scientist, Ignacio Chapela: How are you doing?

Scientist, Dan Janzen: Your alive anyway. I just found your email about two seconds ago.

Scientist, Ignacio Chapela: Which one?

Scientist, Dan Janzen: I don't know, the one that said you are arriving today.

Scientist, Ignacio Chapela: Oh really?

Narrator, Lillian Lehman: Chapela's focus on microbes complements Janzen's main emphasis on insects, and other larger life forms. Between them, they aim for a picture of the total ecology. Studying how all the numerous species, actually need each other, and interact with their environment.

Scientist, Ignacio Chapela: As you walk through the forest with Dan, he's looking at it mostly from the point of view of larger organisms, insects. I'm looking at it from the point of view of microbes. And it is fantastic, very enjoyable to see how those, very different views really ,and complement each other.

Narrator, Lillian Lehman: Ignacio Chapela's specialty is fungi. Fungus, perhaps surprisingly, is a form of microbe.

Scientist, Ignacio Chapela: Fungi are very different to other microorganisms. We know that they are much closer to animals than they are, for example, to plants, and certainly to bacteria. Yet, they are microorganisms. Fungi provide a wonderful link between the microbial world, and the world of larger organisms. Many people don't realize that mushrooms are fungi, and that fungi are microorganisms, therefore mushrooms are microorganisms.

Narrator, Lillian Lehman: Fungal cells are microscopic. But when they grow together, they become visible strands. When it's time for them to reproduce, strands such as these go through a remarkable transformation.

{Echoing synthesizer music.}

Scientist, Ignacio Chapela: Fungi are the supreme decomposers. They can penetrate into pieces of wood, even leaves, and break down the carbon accumulated in these materials. All life on Earth is based upon carbon. Fungi break it down, and respire back into the atmosphere carbon dioxide, making it available in such a way that, again other organisms can take it back. So, in that sense, microbes in general, and particularly fungi in terrestrial ecosystems, are the supreme recyclers.

Narrator, Lillian Lehman: A piece of bread succumbs to decomposing fungi. The fungal cells grow into tubes called hyphae, these release chemicals called digestive enzymes, into the bread. The enzymes slowly turn the bread into liquid, which is drawn into the hyphal tubes, as food. Essential organic chemicals containing carbon, are transformed. In the forest fungi break down complex compounds, and transform them into nutrients for living plants.

Scientist, Ignacio Chapela: The fungus helps the plant capture nutrients that the plant would not be able to capture without the fungus. And the fungus gets, in return, sugars and other nutrients that it also needs to survive. Fungi play, also very important roles, that are just as important as the decomposition. They form a vast network that's, an organized network through the soil and up plant bodies, and all over the landscape. That establishes real communication networks. This communication can happen through nutrient processing, nutrient shuttling from one place to the other. There are plants that establish intimate relationships with that network, and are able to send nutrients from a larger plant, to a smaller one that might be suffering under the canopy, and help her out. Help that other plant out. And, in many other ways, fungi, microbes, form a network that connects the whole forest.

Narrator, Lillian Lehman: The fungal network increases the speed and efficiency of recycling, aiding the lush growth of the whole forest. {Sounds of insects, and birds.} Lurking in the foliage is a major player in the forest drama. Fifty million years ago, a particular species of insect, forged a unique partnership with a certain type of fungus, and a large leap in evolution resulted. The leaf-cutter ants collect leaf fragments by the million, and store them in their nest. In the nest, a fungus decomposes the leaves. The ants eat the fungus.

Scientist, Ignacio Chapela: The fungus provides the ants with a sole source of food. The young and the adults eat solely this fungus, which they feed the leaves to. Can you see the leaves freshly brought in here? All this material is fungus that is being grown on these leaves. These ants, of course, then would never be able to survive without this fungus. The ants provide the leaves to the fungus, and the fungus gives back some food to the ants. So it's a happy contract agreement that they have, just based on nutrition.

Narrator, Lillian Lehman: Once the ants have eaten, the fungus residue in ants droppings become nutrition for other species. Their transported by flying beetles, directly to the roots of trees, and other plants. Fifty million years ago, the ancestors of these ants invented a system so efficient that it took over as much as thirty percent of all the recycling of all the forest foliage.

Scientist, Ignacio Chapela: All of a sudden you have an ant, and a fungus that join forces, and start doing a totally new job in the ecosystem. Life takes a totally new face, and a new form, and starts working differently.

Narrator, Lillian Lehman: Ignacio Chapela, and Dan Janzen combine their expertise in two fields of biology. Together, they are gaining new knowledge of how microbes, and larger forms of life, are connected, and new insights into the complex workings of the Web of Life. Today, all across the world, from Central America, to Ireland, and Indonesia, all plants and trees depend on the microbial world to feed them nutrients. In turn, plants, and trees supply fifty percent of the oxygen we breathe. The rest comes from marine microbes, especially algae, and bacteria. A common form of algae is sea weed, like plants, algae are photosynthetic, but they are microbes. This sea weed is microbes made visible. Across the globe photosynthetic bacteria, and algae are vital to the world's supply of oxygen. The algae draw energy from sunlight, taking in carbon dioxide, and water, and releasing oxygen. The shrimp, and the bacteria in the water, use oxygen, and give off carbon dioxide. It's an endless cycle. Was the microbial, oxygen cycle disrupted in Biosphere 2? Or was there another explanation? How could microbes cause the loss of twenty five percent of all the oxygen?

(Transcript provided by Tyler Anderson)

 

 

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