When you think about animals swimming, growing and thriving in the Great Salt Lake’s water, brine shrimp and brine flies are likely the only two things that come to mind.
But scientists have discovered another multi-celled lifeform that has long called the lake’s salty water home.
Turns out, there are lots and lots of tiny worms called nematodes living in the lake’s microbialites, the rocky round structures built by photosynthesizing bacteria.
“One thing I think is really cool about nematodes is how abundant they are,” said Michael Werner, a biology professor at the University of Utah. “About four out of every five animals on the planet is a nematode.”
Nematodes, sometimes called roundworms, are mostly small — about a millimeter in size. But some can grow bigger than that. One parasitic species that lives in sperm whales, Werner said, can grow to 30 feet long.
Werner came to Utah and started his lab at the U. right when pandemic lockdowns began. Without much to do in the lab, the professor found himself hiking a lot more, including at the Great Salt Lake’s Antelope Island.
“I saw all these signs that said ‘Only brine flies and brine shrimp can live in these waters,’” Werner said. “But I study nematodes, so I was like, ‘I’m not so sure about that.’”
Postdoctoral student Julie Jung came to the U. about a year later, fresh off of studying tree frogs in Central America. She liked the idea of looking for little worms in Utah’s vast salty lake.
“I didn’t know what a nematode was,” Jung said, “and how prevalent they are in the world. It’s fascinating.”
Werner said he was happy to recruit someone used to spending time outside the lab.
“I didn’t have a lot of field research experience myself,” the professor said. “I’m more of a classically trained molecular biologist. So this was kismet for me.”
The pair started their worm survey in the spring of 2021, paddling around the lake. But as the lake dropped to a record low that year, and kept receding the following year, they had to use bikes instead.
“The ground is so soft it’s not compact enough for the bikes to gain traction,” Werner said. “Those were some rough days.”
(Michael Werner) University of Utah postdoctoral student Julie Jung searches for nematodes near some surfaced microbialites.
Their work paid off. The scientists soon found nematodes wriggling on the surface of a microbialite sample.
“I remember this moment we found the first worm was really exciting,” Jung said. “We were stinky and salty because we had collected that day.”
They found about five or six nematodes in total, Werner said, visible only with a microscope.
“We were over the moon, finding these small numbers of worms,” he added. “Then Julie said, ‘You know Michael, I think they might be inside the microbialites.’”
The professor went back to other lab work. Then he heard some banging.
“Julie had taken a hammer and was pulverizing a microbialite,” he said. “She found hundreds, and in some cases thousands, of worms. That really broke open this whole project for us.”
The scientists became curious whether there was something about the microbialites that allowed the nematodes to survive in the lake’s hyper-saline water. The lake’s fresher southern half is still about nine times saltier than the ocean.
They fed some non-lake nematodes bacteria that build the microbialite structures, then exposed those worms, along with worms fed their usual diet, to the lake’s briny water. Within 24 hours, the nematodes fed microbialite bacteria were still alive, while the control worms were dead.
“It opened up this whole exciting area of ecology of what worms are doing in the lake,” Werner said. “Maybe the nematoes are contributing to microbialite formation as well. ... They might be transporting useful bacterial to other parts of the microbialite.”
It also underscores the importance of a healthy lake elevation for supporting life. When the Great Salt Lake shrunk to record lows in 2021 and 2022, it exposed many microbialites to the air and killed off the living colonies that formed them.
“We found nematodes in those ones,” Jung said, “but they were [also] pretty obviously dead.”
Jung and Werner published their findings Tuesday in the journal Proceedings of the Royal Society B.
Bonnie Baxter, a biology professor at Westminster University and director of the Great Salt Lake Institute, has studied the microbialites for decades. She said she’s long suspected nematodes might be living in the lake.
“But to find them in the fabric of the microbialites was fascinating,” she said.
Microbialites are formed by organisms that build photosynthetic mats and pull minerals out of the water, solidifying them into rocky structures layer by layer, year by year. They’re found along cracks and fault lines in the Great Salt Lake’s lakebed where groundwater seeps through.
“They’re made of calcium carbonate, and we don’t have a lot of calcium in this lake,” Baxter said, “so the calcium has to come from underground.”
They’re often compared to ocean coral reefs because they support much of the lake’s life. Brine flies spend most of their lives attached to the structures as pupae, before they turn to into adults, float to the surface and feed millions of migrating waterfowl and shorebirds.
“The way they’re different is coral is an animal, and these are microbes,” Baxter said. “They’re the photosynthesizers of the lake. We think they’re doing more photosynthesis than even the algae living in the water.”
And they apparently help nematodes survive in some of the harshest conditions on the planet.
Scientists reported finding nematodes in 2016 at another salt lake in the West — California’s Mono Lake. Mono Lake also has rock structures called tufas, although they’re formed by freshwater seeps, not microbes. But scientists have been unable to find nematodes living in Owens Lake, another saline California lake with no rocky structures.
Jung and Werner suspect the nematodes they found in the Great Salt Lake may be a new species entirely — possibly multiple species — but that’s another study for another day.
“There’s more life in the Great Salt Lake than people think,” Jung said. “And there’s a lot of beauty in the microscopic.”
This article is published through The Great Salt Lake Collaborative: A Solutions Journalism Initiative, a partnership of news, education and media organizations that aims to inform readers about the Great Salt Lake.
