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Two newly discovered crayfish species are already at risk

For decades, the signal crayfish has been an ecological troublemaker. It is invasive and widespread across Europe, Asia, and parts of the United States. Recently, researchers at the University of Illinois Urbana-Champaign have turned their attention back to the signal crayfish's homeland and made a remarkable discovery.

Their study identified two new species of crayfish in the Pacific Northwest. Long mistaken for the signal crayfish, these two new species—the Okanagan crayfish and misfortunate crayfish—have now been named.

The work is in the journal Zootaxa.

"I think we underestimate how rich the biological world around us can be," said study co-author Eric Larson, associate professor in the Department of Natural Resources and Environmental Sciences, part of the College of Agricultural, Consumer and Environmental Sciences at Illinois. "People are surprised to learn that there are over 600 described species of crayfish globally, and now, there are two more."

This discovery was long in the making, as observations of unusual looking crayfish were investigated over many years using increasingly sophisticated genetics methods. Larson and his colleagues used a process known as genome skimming to sequence mitochondrial and nuclear DNA to compare crayfish lineages. Through this process, as well as extensive field sampling and morphological analyses, the Okanagan crayfish and misfortunate crayfish came to light.

"Most research on the signal crayfish focuses on its role as an invasive species," Larson said. "I think people would be surprised that within its native environment, we missed that this animal we thought was the signal crayfish was actually harboring multiple, undescribed species."

Yet, the excitement of this discovery comes with a conservation warning. Larson worries that the new species are highly vulnerable to extinction, specifically from invasive crayfish species such as the rusty crayfish and virile crayfish—aggressive invaders that displace native populations and damage aquatic ecosystems.

One of the biggest risks to native crayfish is people moving species between ecosystems and waterways. Whether this movement is intentional through fishing bait or aquaculture, or unintentional through classroom releases and aquarium dumps, Larson warns against moving crayfish; one introduction of an invasive species can trigger a cascade of ecological consequences.

"There are unexpected consequences when we move crayfish from one place to another," Larson said. "Invasive crayfish can't easily be removed, and as they spread, they seem to be replacing these newly described crayfish species."

Larson hopes that formally identifying these two new species will do more than add names to the scientific record. Hopefully, it will inspire conservation action, as recognition is often the first step toward protection. By identifying the Okanagan crayfish and misfortunate crayfish, Larson and his team aim to raise awareness and create a case for protecting them.

"By the time we discovered the misfortunate crayfish, it had already lost much of its native range to the invasive rusty crayfish," Larson said. "That's what gave us the idea for its name. This animal went unrecognized by science until a fairly unlucky event had happened, and that seemed like a little bit of a misfortune."

This work represents Larson's larger research mission to study invaders and the native species that suffer in their wake. Originally working as a fisheries biologist, he found his way to crayfish during a doctoral program at the University of Washington and never looked back.

"It's funny, I didn't intend to develop this interest," Larson said. "But as it developed, studying crayfish gained momentum and took on a life of its own."

Now, due to Larson and his team's dedication, these two new animals finally have names—and a fighting chance.