This week in class we watched a video called "The Keepers of the Biosphere," which showed the importance of microbes and their roles in our biosphere and how that ties into our greater ecosystem and web of life. In class, we've been studying the basics of microbes and how they affect everything around us. This video made me want to learn more about the microbes that weren't mentioned by name in the video, like viruses.
Biosphere
The word biosphere refers to the regions on a planet inhabited by life. It comes from the Greek words bios, meaning life, and sphaira, meaning sphere, so it literally means "life sphere." Similarly, the word atmosphere has the root atmos, or air, the word lithosphere has the root lithos, or stone, and the word hydrosphere has the root hydro, meaning water, so the three words are respectively a planets' "air sphere," "stone sphere" and "water sphere." You could also define the biosphere as the global sum of all ecosystems, which draws more attention to the systems of interdependence required for a biosphere to exist.
In the video, we learned about a group of scientists who designed and executed an experiment called Biosphere 2. The goal of this experiment was to create a self-sustaining, closed system miniature version of our biosphere, complete with seven different biomes and a great variety of flora and fauna, including eight human volunteers. Their creation, if successful, would have been a great asset to organizations hoping to sustain life on another planet, such as Mars.
However, Biosphere 2 failed. After a short period of success, oxygen levels within the closed environment began to drop. Animals died, and the volunteers within began having trouble breathing. Unable to reverse the effect in a way that would not harm the purpose of the experiment without knowing the cause of the problem, the researchers were forced to unseal the experiment and pump in oxygen.
At the time, the scientists did not know what went wrong, but once the experiment failed, research began attempting to determine the cause of the oxygen shortage. We now hypothesize that the oxygen drop was a result of two main issues.First, microbes. The soil in Biosphere 2 was very rich in nutrients and organic materials, which provided a lot of food for microbes, which multiplied and began to metabolize at an unusually high rate, taking in more oxygen and producing more carbon dioxide.
Now, usually, the plants within the experiment would have been able to compensate for this by consuming the excess carbon dioxide, but this was prevented by the second cause of the drop, the material the walls of the enclosure was made of. The walls surrounding most of the enclosure were made of a particularly calcium hydroxide-rich concrete, which reacted with the excess carbon dioxide in the air to form calcium carbonate and water instead of feeding the plants.
The failure of Biosphere 2 is a valuable learning experience for scientists studying the Earth and our ecosystems, because it reminds of the things often forgotten, all the factors necessary to consider when hoping to sustain life on a smaller scale, and just in general how little we actually know about the world we live in. Before scientists can even consider eventually successfully sustaining or "creating" life on another planet, they must have a much deeper understanding of everything that contributes to creating our biosphere, including that which we cannot see with the naked eye.
The Perfect Recycling Machine
In "Keepers of the Biosphere," the narrator used the term 'perfect recycling machine.' Humans, with our recycled newspapers and reused brown paper bags, like to consider ourselves recyclers. However, we are not the perfect recycling machine - microbes, collectively, are.
This means they are an integral part of our ecosystem, as their role breaking down waste in our ecosystem and turning it into nutrients is extremely important for maintaining a balance of production and consumption in our biosphere. Calling any individual life form or eve species a perfect recycling machine would be imprecise, however microbes earn this title through their extensive reach. Since the word 'microbe' covers such a huge category of organisms, calling them a perfect recycling machine is referring to the vast network of them that spreads across the Earth, working as a system that is, indeed perfectly suited to recycling. Because they are so important and so much of our ecosystem, a 'broken' recycling machine would be a disaster for our biosphere, and would basically cause our ecosystem to collapse. A broken recycling machine would cause the rest of the system, from the plants and trees fertilized by the microbe-produced nutrients to the animals (including humans) depending on those plants and trees and many other microbe-affected things to break down as well and would likely lead to mass extinction.
Fungi
Fungi, one of the six major types of microbe (as well as one of the four mentioned in class), is an especially important part of the perfect recycling machine. In fact, the video went even further, crowning fungi 'the supreme recycler,' because of how many ecosystems, especially forests and rain forests, rely on a network of fungi to break down and recycle waste into nutrients, making them an imperative part of the carbon cycle. According to the video, another role for fungi is to be a kind of link between the microbial and plant worlds, because they are the most similar microbes to plants, visible because of the large quantities they gather in. Some types of fungi also interact with plants, especially trees, in a more directly symbiotic way, intertwining with their roots and providing easier access to certain minerals in return for water and other organic compounds.
Web of Life
The web of life is the system of interdependence and interaction between all living things. It affects everything and everyone - we are all a part of it. The web of life is necessary for an ecosystem because an ecosystem cannot exist at all without the interdependence of living organisms, and it is that interdependence that keeps an ecosystem in balance.
A metaphor often used for the web of life is a literal spiderweb, accurate in that if one part of the web of life frays, as with a spiderweb, the entire thing can unravel. In that image, microbes are at the edges, providing the basis for plants, then animals, and so on and so forth. However, Dan Janzen, in "Keepers of the Biosphere," went a step further, instead imagining the web of life as a three dimensional network, with microbes as the glue holding it all together. This image is an even better metaphor, because the web of life is both incredibly complex and heavily reliant on microbes.In both of these scenarios, it is vital for the web of life and the ecosystem as a whole to maintain equilibrium. Whether it could metaphorically unravel because of a single frayed thread or fall completely apart without its glue, an imbalanced ecosystem can only lead to a chain reaction of extinctions and disruption. Equilibrium is essential to maintaining a smoothly functioning biosphere, and microbes are essential to that equilibrium.
Glossary:
Microbe: any microscopic organism, as bacteria, protozoa, and some fungi and algae.
Ecosystem: a biological community of interacting organisms and their physical environment.
Web of Life: a system, or a group of interconnected elements, formed by the interaction of a community of organisms with their environment.
Biosphere:
1. the part of the earth's crust, waters, and atmosphere that supports life.
2. the ecosystem comprising the entire earth and the living organisms that inhabit it.
