A new species of worm has been discovered in the Great Salt Lake in Utah, the largest saltwater lake in the Western Hemisphere, according to a new study.
Researchers from the University of Utah believe the species is endemic to the US lake, meaning it is likely found nowhere else on the planet.
The tiny nematode, or roundworm, has been named Diplolaimelloides woaabi, honouring the Northwestern Band of the Shoshone Nation whose ancestral lands include the large waterbody. The name woaabi comes from an indigenous word for ‘worm’, suggested by Shoshone elders after consultation with the researchers.
Given the abundance and importance of nematodes in other ecosystems around the world, the researchers believe the new species plays a vital ecological role in the Great Salt Lake. They also think it could act as a bioindicator of environmental change in region.
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Nematodes are among the most abundant animals on the planet, living everywhere from garden soil to deep ocean floors. There are more than 250,000 known species and about 90% of all animal life on the ocean floor are nematodes. Yet until 2022 none had been officially identified in the Great Salt Lake. That changed when the study’s lead author Julie Jung set out on a series of expeditions by kayak and bike and recovered the worms from microbialites, stony mounds formed by algae and microbes on the lakebed.
“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,” says Jung, a researcher at Weber State University.
The discovery, published in the Journal of Nematology, makes nematodes only the third known group of multicellular animals living in the lake’s hostile hypersaline waters, alongside brine shrimp and brine flies. Further genetic work suggests there may even be a second, currently unnamed species present.
“It's hard to tell distinguishing characteristics, but genetically we can see that there are at least two populations out there,” says co-author of the study Michael Werner.
How did the worms get there?
Exactly how these worms reached such an isolated, salty lake remains a bit of a mystery. One idea is that their ancestors were stranded here millions of years ago when Utah lay on the west shore of an ancient marine waterway.
“So we were on the beach here,” says nematode expert Byron Adams. “This area was part of that seaway, and streams and rivers that drained into that beach would be great habitat for these kinds of organisms. With the Colorado Plateau lifting up, you formed a great basin, and these animals were trapped here. That's something that we have to test out and do more science on, but that's my go-to. The null hypothesis is that they're here because they've always kind of been here.”
According to Werner, northern Utah has not always been home to a salty lake. In fact, between 20,000 and 30,000 years ago, a vast freshwater lake 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.”
Another possibility, Werner says, is that the worms were brought to the lake on the wings of birds migrating from saline lakes in South America. “Maybe the birds are transporting small invertebrates, including nematodes, across huge distances. Kind of hard to believe, but it seems like it has to be one of those two.”
Why is the find important?
Found only in the top layers of microbialites (the mounds on the lakebed), the nematodes feed on bacteria and may be vital to nutrient cycling.
They are also bioindicators of environmental health, say the researchers, explaining that nematode numbers, species diversity and the places they are found can reveal changes in water quality, salt levels and sediment chemistry.
“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,” says Adams. “They tell you how healthy your ecosystem is.”
As human pressures on the Great Salt Lake increase, D. woaabi could act as an “early warning system” for changes in the environment that may otherwise be difficult to detect, the study concludes.
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