Protecting All Creatures Great and Small
Air Date: Week of December 30, 1994
David Baron of member station WBUR examines the concept of preserving all the variety of life — even the tiniest. Microscopic organisms have their own ecosystems and make higher life forms possible, but because of pollution and other changes, many microbes are dying out.
CURWOOD: This is Living on Earth. I'm Steve Curwood. One of the most hotly debated topics in environmental protection is how far to go to protect endangered species. Should we save an entire old growth forest to protect the spotted owl? Stop fishing for tuna to save dolphins? Never buy ivory to keep elephants from extinction? Some scientists say these debates have overlooked a whole category of creatures that can only be seen under a microscope. As much as half of all the living matter on Earth is microbial, yet discussions about preserving biological diversity rarely touch on bacteria, fungi, yeast, and other microorganisms. But there's evidence that the numbers of microbial species are declining, and that a shift in the balance of microbial ecosystems may be putting humans and other larger creatures at risk. David Baron of member station WBUR in Boston has our report.
BARON: A cold wind is blowing through the sagebrush of eastern Oregon's high desert. Snow covers the nearby mountains, and a blizzard is brewing on the horizon. But bubbling out of the ground is a small pool of steaming hot water.
CASTENHOLZ: Well, let's see what the temperature is.
BARON: University of Oregon biologist Dick Castenholz drops a metal probe into the water. It's attached by wire to a digital thermometer he holds in his hand.
CASTENHOLZ: This blows 178 Fahrenheit.
BARON: No plant or animal could live in water of such high temperature, but that doesn't mean this hot spring is lifeless. Castenholz uses a turkey baster to collect some green slime growing on the rock where the water pours out of the pool. He squirts the sample into a glass vial, and carries it to his jeep. In the cab, sheltered from the wind, Castenholz places a drop of water on a glass slide and peers at the sample through a microscope.
CASTENHOLZ: There are very small, little, slightly curved rods, which are about a micron and a half in diameter...
BARON: Castenholz knows these organisms instantly: Synechococcus and Chloroflexus, bacteria which, like plants, get their energy from the sun. The waste from these organisms provides food for other, non-photosynthetic bacteria that live in the hot spring. Those microbes are in turn eaten by tiny crustaceans. Castenholz says this small hot spring, only a few feet square, is home to its own ecosystem like any forest, prairie, or desert.
CASTENHOLZ: It's just a size difference, and complexity is there in the microbial world, too.
BARON: Microbes live virtually everywhere on Earth: in the soil, in the ocean, in our bodies. Even in glacier ice, oil wells, and toxic waste sites: places where nothing else can live. In fact, says University of Massachusetts microbiologist Lynn Margulis, the community of microbes makes higher life forms possible.
MARGULIS: It's that community that cleans the air, that prepares the soil, that cycles the nutrients, and that does all of these things that are sort of - sort of snidely characterized as so-called "ecosystem services" and then dismissed. Well, our lives depend on these ecosystem services.
BARON: Margulis says just as plant and animal species are being lost, the same is likely true for microbes, which represent a far greater variety of life forms than the higher organisms usually discussed in efforts to preserve biodiversity. There are bacteria that thrive in the complete absence of oxygen. Some microbes use sulfur compounds for their energy. And the protists, which includes single-celled creatures such as amoebas, have unusual ways of reproducing.
MARGULIS: These organisms don't have sexes by twos, for example. Some of them have up to several thousand different genders, and these organisms don't ever need sex to reproduce; they can reproduce all by themselves. And yet some of them have birth pangs and they actually have babies through holes. That is, their whole biology is very, very different from the familiar biology of the flower or the - or the mammal.
(Metal doors opening and closing)
BARON: The world's most extensive collection of microbial diversity resides here, in the basement of a 3-story brick building in Rockville, Maryland. The American Type Culture Collection stores its microorganisms in 50 stainless steel freezers chilled to below -200° Fahrenheit. Dick Roblin is one of the collection's associate directors.
ROBLIN: We have in these freezers bacteria, animal and plant viruses, protists, fungi, and yeasts. There are maybe 1.5 million vials of these 64,000 different strains of material in these freezers.
BARON: This huge collection represents only a tiny fraction of the millions of microbial species thought to exist in nature. But the numbers may be dwindling due to the same factors causing plant and animal species to vanish: pollution, development, and destruction of habitat. And among the microbial habitats considered most threatened are hot springs.
(Geyser blowing amidst the honking of geese)
BARON: A small geyser shoots into the air in the middle of a pond with geese standing on the shore. Hunters Hot Springs is about a hundred miles from the pristine hot spring microbiologist Dick Castenholz visited in the Oregon desert. But this area is far from pristine. While the springs are natural, the geyser is the inadvertent result of a well that was drilled in the 1920s. The pond is manmade. And the population of geese has swollen to unnatural levels because locals regularly feed the birds. These human factors have altered the environment for the microorganisms. Castenholz says the microbes used to grow along streams and sorted themselves according to the temperature of the water.
CASTENHOLZ: Instead of having distinct or discrete streams, it's now all been smashed down so it just flows out as a sort of a mud flat. That's because the geese have just trampled this whole area.
BARON: Castenholz doesn't know what the long-term consequences will be for the microbes here. He doesn't think any of them will go extinct. But the same can't be said of organisms in hot springs in other parts of the world that have been pumped dry to feed spas or hydrothermal energy projects.
CASTENHOLZ: In Steamboat Springs, Nevada, near Reno, there were some very interesting and extensive hot springs up in the hillside. And the geothermal drilling above that has completely stopped water flow. They had some unique microorganisms which have found only one other place, and the Steamboat Springs are gone now, so that they don't exist there any more.
BARON: Hot springs organisms can have great practical value. A type of bacteria found at Yellowstone National Park provides an enzyme used in genetic testing and DNA fingerprinting. And it's not just hot springs microbes that are valuable or potentially endangered. Many bacteria and fungi are the source of drugs. And some of these organisms could be vulnerable to extinction, especially those that depend upon a single species of plant or animal for their survival. Rita Colwell of the University of Maryland points to the example of the Sclerosponge, which lives in the Caribbean.
COLWELL: From our studies we know that about half the actual structure is comprised of bacteria found only in association with that sponge. And about 2 dozen of these bacteria have demonstrated some potential activity in treating cancer.
BARON: If this single sponge species found on fragile coral reefs were to go extinct, the bacteria associated with it would be lost as well. Some important fungi are already being lost according to Harvard biologist Edward O. Wilson, who points out that parts of Europe have seen about a 50% decline in fungal species in the past 60 years, apparently due to air pollution. Wilson says many of the species are fungi that live among roots, providing nutrients that are critical for the survival of plants.
WILSON: Ecologists have always wondered what would happen in the land ecosystems if these particular fungi were removed, and unfortunately, we may soon find out.
BARON: But Wilson admits no one knows to what extent microbial diversity is being lost on a global scale. So little is understood about the microbial world, and research funds to find out more are hard to come by. Scientists know it won't be easy getting the public behind efforts to study and protect endangered microorganisms when most people think of microbes only in a context of disease. In fact, the microbiologists' cause may have been hurt by recent debates over the fate of the world's remaining stores of smallpox virus. Those stores are scheduled for destruction June 30th. But some scientists have argued even smallpox should be protected from extinction. Biologist Lynn Margulis says public attention should really be focused on the vast majority of beneficial microbes people rarely notice.
MARGULIS: These organisms have no constituency; nobody's going to work and screaming for them on a daily basis. On the other hand, if they were to stop doing their function, life would die on the planet. Completely. The specialists have done a very bad job in making the case for their importance.
BARON: But that's changing. Microbiologists have stepped up government lobbying for research funding. And some suggest it's time to begin establishing microbial preserves. In fact, just last year Dick Castenholz, who's been fighting to save the microbes of Oregon's hot springs, scored a victory. When the Nature Conservancy purchased a small lake in the Oregon desert to protect an endangered minnow, it also bought at Castenholz's urging a series of hot springs nearby. The springs aren't home to any plants or animals, but Castenholz points out they're teeming with life nonetheless. For Living on Earth, I'm David Baron.
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