July 1, 2017 | David F. Coppedge

Life Helps Protect the Planet

When humans make a mess of things, our fellow organisms try to help. That’s no excuse for our failures to be good stewards.

Oil Cleanup

The Deepwater Horizon oil spill in July 2010 was, without controversy, a terrible disaster brought on by human incompetence. Many species of marine organisms died, beaches were fouled, and teams had to go to extreme lengths to try to clean up the mess. But did all that oil just stay in the water? Remarkably, a new paper in PNAS shows, bacteria quickly ate up much of it. Some microbes are known to degrade oil, but the extent of bacterial assistance in the recovery has not been appreciated till now. Science Daily asks, “What happened to the Deepwater Horizon oil plume?” and answers, “Researchers simulate spill, discover new bacterium, map microbe activity.”

Some bacteria were known to feed on hydrocarbon seeps in the Gulf of Mexico, but the oil spill gave them—and other previously unknown species—an opportunity to bring good out of human error. Microbial biologist Gary Anderson from Berkeley describes what happened:

“Naturally occurring microbes at this depth are highly specialized in growing by using specific components of the oil for their food source. So the oil droplets provided a large surface area for the microbes to chew up the oil.

Working with Berkeley Lab scientist Jill Banfield, a study co-author and also a professor in UC Berkeley’s Department of Earth and Planetary Sciences, the team used newly developed DNA-based methods to identify all of the genomes of the microbes that used the introduced oil for growth along with their specific genes that were responsible for oil degradation. Many of the bacteria that were identified were similar to oil-degrading bacteria found on the ocean surface but had considerably streamlined sets of genes for oil degradation.

Plastic, Too?

Many are rightly concerned about the accumulation of plastic in the oceans. There’s no excuse for it, and we humans must work together to stop it. But in another surprising discovery, there’s far less of it out there in the North Atlantic Gyre than expected. What’s happening? Michael LePage at New Scientist says,

In fact, there’s only a tenth to a hundredth as much plastic as expected – and the amount of floating plastic does not appear to be increasing. “The trend should be there,” Sole says.

This lack of trend cannot be explained by physical processes, according to his team’s mathematical models. Instead, they propose that there has been a population boom in microbes that have evolved the ability to biodegrade plastic.

But have they really “evolved” this ability? It would be a remarkably fast case of evolution if they did, since humans have only been manufacturing plastic for about a century. Another possibility is that they already possessed genes to break it down, much like the highly-touted case of bacteria that supposedly evolved the ability to digest nylon (see Evolution News for refutation). LePage goes on to say that nobody really knows what microbes are capable of.

In theory it is possible that some microbes have evolved the ability to break down plastics. Studies by Linda Amaral-Zettler of the Netherlands Institute for Sea Research show that the microbes colonising floating plastic are quite distinct from those in the surrounding water, and suggest some are feeding on pollutants.

In effect, the plastic is creating a whole new ecosystem that Amaral-Zettler and colleagues call “the plastisphere”.

But when ter Halle looked at the DNA of the organisms on floating plastic in the North Atlantic, she didn’t find any microbes known to be capable of breaking down plastic. That could be because they have not yet been discovered of course – there could be millions of unknown microbes still.

It’s too early to say that microbes are helping clean up the human-caused pollution. They could, in fact, just be reducing the pollutants to millimeter-sized pieces we can’t detect. If so, the plastic could still infect the food chain. Sea turtles and whales are among the large animals that suffer and die from ingesting large pieces of plastic, parts of fishing nets and mylar balloons. The pollution must be curtailed, no matter what is going on. It’s just interesting to find another case of microbes that might be helping clean up after humans.

Anti-Erosion Trees

Larger organisms can also affect the planet. A new study posted by Phys.org says that coastal mangrove forests are 800% more effective at protecting Florida beaches from erosion than salt marshes or artificial protections. Mangroves work well because their “dense tangles of prop roots … serve as highly effective shields for coastlines by reducing the force of breaking waves, decreasing erosion and increasing sediment deposition.” Conservationists would do well to increase their spread. “In all, mangrove habitats could provide $4.9 million worth of coastal protection more than manmade barriers,” scientists estimate.

Atmospheric Cleansing

Even without microbes, the atmosphere has a trick to help clean up pollution. Nature discusses the “self-cleansing ability of prehistoric air,” showing that even without human error, the Earth sweeps the atmosphere clean regularly. Hydroxyl radicals (OH), produced by UV light, the breakdown of ozone and water vapor, last only for a few seconds but attach to pollutants and neutralize them. There are many unknowns in this process, the articles point out. But then, these uncertainties also call into question the confidence of the consensus about climate change. A new study had some surprising results about the function of hydroxyl radicals to temperature:

The new results highlight once again how little we understand about the complexity of chemistry–climate feedbacks and, more generally, of how strongly Earth-system processes are interconnected. Tropospheric composition is driven in different ways by the ocean, cryosphere (the part of the Earth system that is frozen water), lithosphere (Earth’s rocky, outermost shell) and the land and marine biospheres, but also by the stratosphere. It will be crucial to develop a better understanding of the feedback mechanisms involved to more accurately predict how anthropogenic emissions might affect climate and air quality in the future. In particular, a deeper understanding of how atmospheric composition — especially the lifetime of greenhouse gases — is affected by climate change will be important when using results from climate models to inform policy decisions about how global warming can be kept below certain temperature targets.

Writer Michaela I. Hegglin ends by encouraging atmospheric scientists to tie their models to actual observations. “Simulations should not simply be ‘tuned’ to provide the best reproduction of the present climate, but should be built on an understanding of the processes involved, to allow the credible simulation of both past and present climates.” Why? Because climate feedbacks remain “relatively unexplored” at this point, despite the political trust put on climate models.

Natural cleansing systems are no excuse for humans to pollute the planet. The extent to which our actions could overwhelm these automatic rescue processes is unknown. Still, it is quite remarkable that they work so well. Is any exoplanet around other stars so blessed?



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