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Conservationists pride themselves on protecting all of Earth’s life, not just the flashy panda bears and tigers. The field has focused on obscure desert pupfish, insects, and modest little herbaceous plants. But conservationists seldom put bacteria on a tote bag, even though most life is microscopic. Earth has something like a trillion species of bacteria, fungi, archaea, and protozoa–the families of life grouped under the general heading of “microbes.” The sea is a soup of microbes, the soil a wonderland of imperceptible life; even the air is alive. Every day, hundreds of millions of viruses and millions of bacteria float in the air. We’re living in an “English drizzle of microbes,” Kent Redford, a consulting conservationist in Maine who previously held a top post at the Wildlife Conservation Society, told me.
The word microbes is sometimes used synonymously with germs, but there’s a growing understanding that most microbes are not the enemy, and that they keep everything on the planet–including humans–alive. Without the proper microbiome, animals can become sick and even kill themselves. To thrive, plants also need microbial partners. Microbes are the glue that holds ecosystems together (sometimes quite literally: Soil clumps into particles in part because of mucus that microbes secrete. )
But though microbes are ubiquitous, some communities of microbes could be at risk of extinction. In Yellowstone National Park, visitors are forbidden from entering many of the hot springs and geysers, in part to protect the rare microbial communities that call them home. Unique microbial ecosystems in subglacial Antarctic lakes that have been isolated for millions of years are carefully sampled using methods least likely to contaminate them with organisms from beyond the ice.
The conservation movement, however, pays little attention to microbes: As of 2012, only 2 percent of academic papers on conservation focused on these organisms. “Many conservation organizations are largely uninterested in extending their work to microbes,” according to Redford, who just published a plea in the journal Conservation Biology for conservationists to consider the microbial world. Conservationists ignore microbes and neglect other life forms that are important to the survival of all living things on Earth.
Conserving microbes is different from conserving sea otters. A single species of microbial organism or subspecies should not be the main concern. Microbes are actually kind of hard to eradicate because microbes are fantastically numerous, reproduce quickly, and can swap genes with their neighbors, they adapt well to environmental change. There’s a lot of “functional redundancy” in the microbial world. If pollution or climate change or an herbicide knocks out one kind of bacteria that moves nutrients or carbon around in an important way, there are often hundreds of other types of bacteria that do the same thing.
Rather than worrying that climate change or agricultural methods will make an individual species of bacteria go extinct, Redford’s concern is more that these forces will wipe out or radically change microbial communities–with complex and hard-to-predict consequences for the larger ecosystem. Wild trout eggs can be covered with a variety of bacteria from many different families. When climate change heats up stream water, that can radically alter the types of bacteria that live on the eggs, or reshuffle which types are common and which types are rare. And this new community might also be toxic to the trout eggs themselves, endangering the trout. Redford said that you can’t conserve microbes just for their sake. It is impossible to achieve the things you love unless they are included.
Taking microbes into account can help more traditional conservation targets, such as rare animals. For example, many translocations or reintroductions of species done in the name of conservation fail–and in some cases, that might be because the microbial context was not taken into account. Studies have shown that animals in captivity often have very different microbiomes than wild animals of the same species. Redford wanted me to picture a zoo-zebra being taken from Paris and released in Serengeti National Park in Tanzania. “It had a Parisian-zoo microbiome for eating French hay and pelletized alfalfa. And then all of a sudden, its microbiome was asked to digest Serengeti grasses.” It might get sick or simply fail to absorb the needed nutrition from its food.
Conservationists don’t always ignore microbes: Some who are working on reintroducing the endangered Yangtze sturgeon even “trained” their captive fish on more wild, unprocessed foods in an effort to shift their gut microbe to a more natural ecology–and they saw improved survival rates over untrained sturgeon. Many plants have a microbiome, which means that they rely partially on other fungi and their roots for nutrients and water. Translocated plants without the right root fungi are much more likely to die after being outplanted. Researchers working on prairie restoration in Indiana found that introducing the right fungi during restoration increases plant diversity by about 70 percent.
Considering microbes as factors in the survival of plants and animals is becoming more common, especially as the tools needed to detect and sequence microbial genes are becoming more affordable. However, there is less effort to conserve microbes. In part, that’s likely because conservationists already have so much on their plate. Because microbes don’t fall neatly within the species boxes, conservationists find them difficult to tackle. Species are also core units for conservation. We typically measure “biodiversity” by counting species; we know we’ve failed when a species goes extinct. The Endangered Species Act is America’s main policy instrument for protecting non-human species. Yet, the Endangered Species Act is America’s central policy tool for protecting nonhuman species. They are quick to evolve, can hybridize easily, and share genes with other linesages.
“They’re all busy using horizontal gene transfer to move genetic elements around to each other quite happily,” Redford said. And sometimes they live in mixed-lineage groups called biofilms, physically attached, communicating with one another, and operating almost like a single organism. You may be intimately acquainted with biofilms if you have ever scraped plaque off of your teeth. This dynamic, frothy riot of life is difficult for conservationists to integrate into their existing frameworks. They can’t count or make lists of endangered microbe species.
I asked Redford to envision a world in which his appeal was heard and where microbes are fully integrated into conservation and restoration. It would be like for someone who manages a stream of trout. He said that a conservationist could use an environmental DNA detector handheld to obtain a complete picture of the microbes in the water. This would allow them to see the composition of fish, their guts and gills as well as the aquatic plant’s surface. She would have to be able to see how the invisible world of microbes affects what is visible: shading willows and hovering damselflies as well as swirling trout. To get the most out of this information she needs to understand the complex interactions between these microbes. Perhaps her data could also help locate a rare strain of bacteria in the stream that she wants to protect, and she could learn that it needs cool water to thrive. We might plant willows in order to cool down streams.
Conservation in general is moving away from simply putting things “back the way they used to be” and toward helping dynamic ecosystems adapt to changing conditions. Because microbes are constantly evolving and changing, there is less to worry about. It would be impossible anyway; they are just too damn fast. But that embrace of adaptation also opens the door to the possibility of influencing the trajectory of microbial communities–or even incorporating engineered microbes into ecosystems. Sewage-treatment plants already employ diverse communities of bacteria, archaea, and protozoa to clean up water–and even to turn sewage into bioplastic. Meanwhile, a recent study identified a bacteria that can actually break down plastic completely–destroy it for good–and turn it into carbon dioxide. The future conservation strategy might include learning how to manage the ecosystems that allow bacteria to thrive.
Conservation has always had selfish goals, but they can also be altruistic. We want to save species and protect ecosystems because they keep us alive and happy, but we also want to protect the nonhuman world for its own sake. Microbial conservation could also be affected by both of these goals. Bacteria, archaea, and microscopic fungi can improve our lives. Redford believes they can be valuable by themselves and that no one’s size or membership in an animal kingdom determines their moral worth. The unique microbes have developed over many millions of years. They are just like the panda or whale.
The idea that each day we move through millions of people and groups with intrinsic moral worth can give rise to ethical vertigo. It is hard enough to determine how to do right by the plants and animals we share the Earth with. What, if anything, do we owe the fungi and bacteria that invisibly shape our lives?
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