A black goo was oozing from a ship on the Great Lakes — and teeming with life

By Taylor Nicioli, CNN

(CNN) — Research vessel Blue Heron trawls the Great Lakes, gathering data from the water. The floating laboratory’s most recent discovery, however, came from an unexpected location: its own rudder.

While docked after a long cruise to study algae blooms in lakes Erie and Superior in September, the crew noticed a black, tar-like substance oozing from the rudder shaft, the mechanism that allows the 87-foot-long (nearly 27-meter-long) boat to change directions. Unsure of what the odd goo was, Doug Ricketts, marine superintendent and senior research associate at the University of Minnesota Duluth’s Large Lakes Observatory, brought a cup of the substance to the observatory’s scientists for testing.

The scientists were surprised to find that the material was teeming with life-forms, some of which were unknown microorganisms. The mysterious substance, now informally named “ShipGoo001,” had seemingly been thriving in the oxygen-free environment of the rudder shaft, according to a June 27 university announcement.

“There’s no reason to expect any living organisms to be in this part of the ship,” Ricketts said, referring to the closed-off rudder shaft housing. “This particular piece of a ship doesn’t really move a lot. It’s not exposed to the rest of the world.”

If more goo is found, the goal will be to collect it without disturbing its oxygen-free environment, said lead researcher Cody Sheik, a microbial ecologist at Large Lakes Observatory. More careful study could lead to further discovery of new species of microbes, he added.

“One of the things that’s fun about this, is that it was very unexpected. … All of these different things that we make become new habitats that (could be) right for microorganisms,” Sheik said. “It makes me wonder: What else are we missing by not going out and just looking at something?”

Studying the mysterious goo

While some of the DNA extracted from the black goo was found to be from previously unknown microorganisms, other genetic material in the sample has been observed across the world. When researchers searched global databases, they discovered some DNA was related to microbes from a tarball-type substance in the Mediterranean, a hydrocarbon-contaminated sediment in Calgary, Alberta, and other samples from the coast of California to Germany.

“It’s kind of all over the board in terms of what sort of environments these things are being found in,” Sheik said. “I think we’ll get a better idea of what these organisms are capable of by thinking more broadly about the other environments that they’re found in.”

The researchers still have many unanswered questions about the odd material, including how it came to be on the ship and whether it is capable of biocorrosion — eating or degrading the ship’s steel. Since the substance was in its own sealed environment, it would need a complex food web to be able to thrive and sustain itself.

“(Biocorrosion) is one of the things we have to worry about in oil pipelines and all these other really key infrastructure places. And so, you know, for some of these ships, especially the ones that are really long-lived here on the Great Lakes, because they’re in fresh water, is this something where they could be corroding this area? It may be something to think about for future iterations of shipbuilding and things like that,” Sheik said.

Researchers hope to answer these questions in a forthcoming research paper, which will also include the full genomes of the goo’s microorganisms so other scientists can build on their work, Sheik added.

Depending on what the researchers find, the material could have practical applications; methane-producing organisms in the substance could have potential use in biofuel production, according to the university’s announcement. For now, researchers are keeping an eye out for more of the substance in the ship, and on other vessels, so they can gather additional samples and run further tests.

The origin of the goo

Because there are so many microbial species in the world — potentially up to 1 trillion — finding a new one isn’t particularly surprising, said Jeffrey Marlow, an assistant professor of biology at Boston University. “It’s all about where they’re found and what their genomic history or metabolic capacity is — that’s what often makes a new species particularly exciting,” he added in an email.

To ascertain the origin of the substance, Sheik and his team are putting together a history of the ship, as the former fishing boat was purchased pre-owned nearly three decades ago by the University of Minnesota Duluth. While the ship’s rudder is not meant to be lubricated with anything other than water, it’s possible that the previous owners oiled that area and those organisms laid dormant for years. What’s more, the goo was not present during the ship’s last inspection in November 2021.

Marlow, who was not involved in the discovery, hypothesized that the ooze could have wound up in the rudder shaft by catching a ride on marine snow — clumps of dead organic matter that sink through the water column and contain oxygen-free pockets, he explained.

Sheik plans to explore the goo’s origin, noting that there are many scenarios to consider, including whether the substance grew in the rudder shaft in the first place or somehow hitched a ride on the boat.

“One of the coolest parts of this story is the fact that the sample made it to the microbiologists in the first place — it speaks to a ‘microbiologically literate’ culture where several people had the awareness and curiosity to ask what might be living in an otherwise inconvenient ooze,” Marlow said. “It makes you wonder what other fascinating microbes could be living around us in the most unexpected places.”

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