Signs of Fall 5: Life Overhead and Under Foot

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Every summer I spend quite a few hours scrubbing away the algae that grows in the warm water of my birdbath. My assumption is that the algal spores and cells that are making this green, sticky mess are being blown into the water from the surrounding soil and vegetation. However, based on a paper presented at this summer’s American Society of Microbiology in San Francisco, my assumed model may be far too simple: some of these algae may be dropping in from the clouds overhead!

Analysis of condensed cloud water and rain water at a meteorological station in France revealed a diverse group of photosynthetic microbes (“algae”) actually living in the atmosphere. Further, the group that conducted this research (a team from Rutgers University in the United States and the Universite Clermont Auvengne in France) found high ratios of RNA to DNA in their cloud water samples suggesting that the algae were, in fact, actively photosynthesizing up in the clouds!

The impact of atmospheric photosynthesis on global energy fixation and carbon cycles could not be determined from this study, but the evidence that algae in the atmosphere are actively fixing sunlight via photosynthesis is clear. Wouldn’t the sky look different if clouds were green?

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This summer a paper published in the Geomicrobiology Journal described another portion of the Earth’s biosphere that is even more removed from our terrestrial and aquatic ecosystems than the algae living up in clouds. Drilling in a deep copper and zinc mine in Ontario, Canada researchers tapped  into ground water that was trapped in rock fissures 2.4 km below the Earth’s surface. This water is estimated to be billions of years old, and it contained bacteria!

These bacteria live far below the sunlit surface of the Earth and have energy systems that rely on the oxidation of hydrocarbons, hydrogens or other reduced molecules or atoms that are derived from the rocks themselves. They then primarily use non-oxygen final electron acceptors like sulfates or nitrates to sweep the energy depleted electrons out of their electron transport systems. Total available energy is quite low in these systems , but as long as temperatures are not too great and liquid water is available bacteria are almost always found at depths into the Earth’s crust up to 3 or 4 km.

Scientist speculate that bacteria inhabit the entire upper portion of the Earth’s crust and represent a significant proportion of the Earth’s living biomass and genetic diversity. It is silent, separate world that would continue to exist as long as the heat of the Earth persisted regardless of any events that might affect the living systems on the surface of the planet.

Photo by NASA, Public Domain

And, when you look up into the night sky at the moon, you might get a inkling of a new location brought into the umbrella of Earth’s biosphere thanks to a non-profit organization called the Arch Mission Foundation and an unfortunate accident during the  landing of a probe on the moon’s surface.

Arch Mission Foundation was established in 2015 by two extremely wealthy Texans. The mission of this foundation is to create multiple, redundant “libraries” of human knowledge and scatter them throughout our solar system. The Foundation utilizes “5D” laser optical quartz discs to encode the selected knowledge of humanity.  These discs are said to be readable for 14 billion years and capable of withstanding both cosmic radiation and temperatures up to 1000 degrees C without significant damage or degradation. A satellite containing one of these Arch library discs was launched into low Earth orbit in 2016, and another was included in the Tesla Roadster sent into orbit around the sun by Elon Musk’s Space X company in 2018. An attempt was also made to place an Arch Mission Foundation library on the moon in 2019, and this is where something biological occurred.

The Arch Mission disc sent to the moon in addition to containing almost all of the English language Wikipedia and all three volumes of Isaac Asimov’s Foundation trilogy also contained samples of human DNA and thousands of dehydrated tardigrades.

Tardigrade. Photo by E. Schokraie et al.

Tardigrades are an old, invertebrate phylum (their fossils have been dated back over 530 million years) consisting of about 1200 species of very small (less than 0.5 mm in length) individuals that mostly eat bacteria and plant cells in water film environments typically on mosses and lichens. Tardigrades are most notable for two amazing biological characteristics: 1. They can shut down their metabolic process and lose 99% of their body water and enter an extended state of suspended life called “cryptobiosis.” And, 2. They can survive extreme environmental conditions (chemical toxins, very cold temperatures, very hot temperatures, high atmospheric pressures, vacuums and exposure to radiation (both ionizing and UV)) that would kill just about any other multicellular animal. They can even survive extended exposure to the cold, radiation-rich, vacuum of outer space (10 days in 2007).

The probe sent to the moon in which the Arch Mission library and biological material collection was contained, unfortunately, crashed landed and spilled all of it cargo over the moon’s surface, and in the debris was the container of the dehydrated tardigrades. Experts are quite sure that the tardigrades survived both the crash and the exposure to the harsh conditions on the moon’s environment. Having no water for re-hydration nor bacteria to eat, though, it is unlikely that they will become active, but they are, technically, “living” on the moon!

The Earth’s Biosphere is expanding!

Yosemite Valley. Photo by D. Sillman

And finally, and a bit more down to Earth: I have written many times about the benefits of hiking and being outdoors, and a paper published this past summer in the journal Scientific Reports actually quantified the amount of time required to obtain the health benefits of an outdoor experience. Previous research has indicated that people who spend time out in Nature have a lower risk of asthma, allergies, diabetes and cardiovascular disease. Also, their overall mental health is improved and their life expectancy is lengthened. The question that needed to be answered, then, was how much time is needed to get that wide range of positive impacts?

The research group that authored this paper was led by an environmental psychologist at the University of Exeter Medical School in England. The group studied data from almost 20,000 people who were questioned about their levels of regular outdoor activity and current states of health. The data was amazingly consistent: two hours (120 minutes) a week spent out in Nature yielded the most significant levels of health benefits.

“Nature” in this study was defined as any type of natural environment from urban parks, backyard gardens to true wildernesses. Simply spending time outdoors for two hours a week significantly improved an individual’s overall physical and mental health.

The exact mechanisms of this health benefit has not yet been identified, but increased physical activity, increased degrees and qualities of social interactions with other people, exposure to sunlight (and, thus, increased Vitamin D synthesis), removal of oneself from sources of indoor air pollution or artificial lighting, or simply just stepping away from the stresses of work and daily life may all be components of this health benefit. In a number of countries (including Sweden, South Korea and Scotland) medical prescriptions for outdoor activity are becoming increasingly popular. As one physician quoted in the article indicated, it’s “low cost and low risk. Just what the doctor ordered!”

So, algae in the clouds, bacteria in deep rocks of the Earth and tardigrades on the moon! No wonder Nature is so good for us!