Great Salt Lake Reveals New Microscopic Worm Species

Researchers have discovered a new species of microscopic worm in the Great Salt Lake, expanding its known biodiversity, and potentially offering scientists a new tool for monitoring environmental change. A team of researchers from the University of Utah documented the new species of nematode living in the lake’s hypersaline waters. Called Diplolaimelloides woaabi, this species appears to be unique to the Great Salt Lake. Alongside brine shrimp and brine flies, it is one of the few animals able to survive in such salty conditions. Published in the Journal of Nematology, the findings raise new questions about how animals survive in extreme environments and about the history of this nematode in the lake. A Species Hidden in Plain Sight Nematodes, also known as roundworms, are one of the most common animals on the planet, with more than 250,000 species identified. They account for about 80% of animal life in soils and 90% of animal life on the ocean floor. Most are less than a millimeter long, making them easy to overlook. Researchers had not documented nematodes in the Great Salt Lake until 2022. That year, fieldwork led by researcher Julie Jung discovered that nematodes were living inside the lake’s microbialites. Jung paddled across the lake in a kayak and biked the perimeter to collect samples. “We thought that this was probably a new species of nematode from the beginning, but it took three years of additional work to taxonomically confirm that suspicion,” said Jung, now an assistant professor at Weber State University. Naming the New Species Researchers worked with elders from the Northwestern Band of the Shoshone Nation to select a name that reflects Indigenous heritage. The species was formally named Diplolaimelloides woaabi. “Wo’aabi” is an Indigenous word meaning “worm.” Led by University of Utah biology professor Michael Werner, the team confirmed that Diplolaimelloides woaabi only live in the Great Salt Lake. Its presence adds nematodes to the short list of animals able to survive the lake’s high salinity, alongside brine shrimp and brine flies. These species play a crucial role in supporting the millions of migratory birds that rely on the lake as a feeding ground. Genetic analyses suggest there may be even more diversity among nematode populations in the lake than previously thought. “It’s hard to tell distinguishing characteristics, but genetically we can see that there are at least two populations out there,” Werner said, noting that the samples may include a second, previously unknown nematode species. A Mysterious Arrival The discovery of a Diplolaimelloides nematode in the Great Salt Lake raises questions about how this species arrived and adapted to such an isolated environment. Most species in the Diplolaimelloides group live in coastal marine or brackish environments. Researchers have recorded only one other species far from the ocean, in eastern Mongolia. The Great Salt Lake, by comparison, sits about 4,200 feet above sea level and is roughly 800 miles from the nearest coast. “That begs some more interesting, intriguing questions that you wouldn’t have even known to think of until we figured out the alpha taxonomy,” Werner said. “There are two hypotheses, two models that are both kind of crazy for different reasons.” One hypothesis suggests that nematodes have lived in the region for millions of years. During the Cretaceous Period, much of what is now Utah was on the edge of a large inland sea that once split North America. “So we were on the beach here,” said coauthor Byron Adams, a nematologist and biology professor at Brigham Young University. “With the Colorado Plateau lifting up, you formed a great basin, and these animals were trapped here.” However, evidence shows that between 20,000 and 30,000 years ago, a large freshwater lake known as Lake Bonneville covered the region. “If the nematode has been endemic since 100 million years ago, it has survived through these dramatic shifts in salinity at least once, probably a few times,” Werner said. Another possible explanation is that migratory birds carried the nematodes between saline lakes, with the worms possibly hitching a ride on feathers. “Kind of hard to believe,” Werner said, “but it seems like it has to be one of those two.” An Indicator of a Changing Lake The nematodes live in algal mats on microbialites and feed on bacteria in the upper layers of these formations. Scientists often use nematodes as bioindicators; therefore, changes in their populations can signal shifts in water quality, salinity, or sediment composition. “When you only have a handful of species that can persist in environments like that, and they’re really sensitive to change, those serve as really good sentinel taxa,” Adams said. “They tell you how healthy is your ecosystem.”