Underwater volcano eruptions allow new bacteria to take over seafloor
What happens when Nature decides to push the "reset" button on an ecosystem? The answer can be found in the aftermath of the submarine volcanic eruptions that took place off El Hierro in the Canary Islands between October 2011 and March 2012. The resulting magma vaporized everything in its path, providing a fresh blank slate for a mysterious organism never before seen by scientists to move in and restart life in the area.
Lasting 138 days, the eruptions were nothing short of apocalyptic, wiping out all life forms for nine square kilometers (3.47 square miles). Water temperatures shot up by as much as 18.8 degrees Celsius (65 degrees Fahrenheit) and oxygen levels plunged as the affected area turned into an acidic soup bubbling with carbon dioxide and sulfur hydroxide.
And yet what marked the end for the affected area's marine life turned out to be the beginning for a new organism never before documented by scientists. When Spanish and Italian researchers visited the site in 2014 to study the aftermath of the eruption, they found what appeared to be a lush, undulating white shag carpet blanketing 2,000 square meters of the volcanic sea floor.
Samples were taken of the lustrous hair-like filaments, which they named Venus' Hair (Thiolava veneris) – after the Roman goddess of love, who was born of sea foam – as well as its ability to thrive in its sulfurous environment (thio stems from the Greek word for sulfur).
Analysis revealed the filaments, which were around three to six centimeters long, housed bacteria of the extremophile variety with "an unprecedented array of metabolic pathways" that allow it to survive in toxic submarine volcanic environments. These include the ability to harness the sulfur compounds in the water as an energy source (just like the giant shipworm that recently took the scientific community by storm).
"The bacterial group in this new volcano shows a set of differential traits when compared to other bacteria," says lead researcher Miquel Canals, a professor of marine geosciences at the University of Barcelona. "None of the identified genomic extracts has photosynthesis-related genes, so this process is ruled out from the microbial filament metabolism."
Unsurprisingly, there's plenty that remains a mystery where this strange new bacteria is concerned. For a start, scientists are still trying to figure out where Venus' Hair comes from and how it got to the area in the first place. While underwater volcanic eruptions are nothing new, this is the first time these white hair-like growths have been documented on the sea floor. Canals doesn't think it likely that they originated from other underwater vents given that the newly-formed Tagoro is shallow and isolated from other areas with volcanic activity, such as the mid-Atlantic ridge.
That said, it is not unheard of for immigrant species to colonize an area that has been devastated by a volcanic eruption. Case in point: when the vents near the East Pacific Rise erupted between late 2005 and early 2006, smothering the aquatic communities in the area with lava, scientists had expected to find the same species that had once thrived in the vents returning to the area. Instead, they found it overrun with two particular species of limpets that were not endemic to the area. Scientists are still not sure how sea snails from 300 kilometers (186 miles) away ended up colonizing those vents, but it just goes to show there's still a lot we don't know about the ocean's inner workings.
Life after death
While it's anyone's guess when the bacteria started setting up base on the sea floor, the researchers suspect that it happened not long after the temperature dropped to a sustainable level, most likely below 100 degrees Celsius (212 °F). What is evident is that it is driving the reboot of the ecosystem as it anchors itself to the volcanic rock, paving the way for other small creatures such as nematodes, worms and crustaceans to move in and start the circle of life all over again.
For microbial oceanology and ecology expert David Kirchman of the University of Delaware, these findings could shed light on the origins of life. While one might wonder how the Venus' Hair bacterium came to colonize the barren volcanic rock, "perhaps work could address even broader questions about where and how a cell first formed to take advantage of geothermal energy like microorganisms now do at the Tagoro volcano," he writes in a Nature News and Views editorial article about the discovery.
The study was published in Nature, Ecology & Evolution.
Source: University of Barcelona