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California's Saltiest Lake Is Chock-Full of Bizarre Roundworms



If human, the waters of Mono Lake aren't for you. Apart from being an otherwise worldly strain of water, the Californian body of water is salty and very basic, with a pH of 10 — the equivalent of detergent — in addition to arsenic levels around six times what is considered safe for drinking. No fish live in the lake, but some animal life finds a way, namely those thrive in the harshest conditions (collectively known as extremophiles). Mono Lake's inhabitants have names that refer to their hostile home: brine shrimp and alkali flies. Now, another hardy species can be added to Mono Lake's list of aquatic denizens — nematodes, including a new, arsenic-adoring species from the genus Auanema.

The creature, described in the journal Current Biology, is a roundworm with a couple of unique evolutionary traits, chief among them the capacity to survive more than 500 times the amount of arsenic that is fatal to humans. But James Lee, a former nematologist at the Sternberg Lab at the California Institute of Technology who conducted the research, was all too surprised to find them.

"What is remarkable about extremophilic nematodes — in fact all extremophilic species — is how much they have to show about resilience, and the innovative strategies they use to survive on this planet," he says.

Mono Lake is as beautiful as it is inhospitable to most creatures.
Mono Lake is as beautiful as it is inhospitable to most creatures. Courtesy James Lee

The newly discovered species of Auanema has a few other evolutionary tricks up its oral cavity. It has three sexes — female, male, and hermaphrodite. Lee says the male and female Auanema may help preserve genetic diversity in established populations, while hermaphroditic worms are uniquely suited to trailblazing into new areas as they reproduce solo. The nematodes are also viviparous, meaning that instead of laying eggs like most nematodes, they have live births.

Lee and his colleagues are particularly excited about the new Auanema The species' arsenic resistance, which, while documented in two other nematodes, has never before appeared in an extremophilic one.

“We believe this could shine new light on how arsenic moves through and affects animal cells,” he says, “an open question that is especially important since arsenic is one of the most common environmental toxins that affects humans.

The new nematode species. Not pictured: All the arsenic in it.
The new nematode species. Not pictured: All the arsenic in it. Courtesy James Lee

The nematodes at Mono Lake also confirm a long-held truth: that nematodes are not only one of the most robust creatures on earth, but they are also among the most abundant. In 1913, nematologist Nathan Cobb wrote that “if all matter in the universe except the nematodes were swept away, our world would still be dimly recognizable… we would find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. ”Mono Lake would come through clear.

"These animals have really mastered how to survive on this Earth," Lee says. "We could really learn a lot from them."


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