Researchers at the University led by Eric Larson, professor in ACES, made a groundbreaking discovery pertaining to the Signal Crayfish. They found there are two distinct species of crayfish residing in the Pacific Northwest that were previously both mistaken for the Signal Crayfish.

Hiding in plain sight

The study identifies the Okanagan and Misfortunate Crayfish as two new species, adding to a list of over 640 global crayfish species. The Signal Crayfish is native to the Pacific Northwest, but most of its research has investigated it as an invasive species. Studying the species in its native habitat unlocked a new layer of biodiversity.

According to Larson, this is a common occurrence when studying invasive species.

“(The Signal Crayfish have) been really well studied as an invasive species in those places where it’s not native,” Larson said. “But in a lot of ways, it was neglected in its native range. And that happens commonly, that invasive species get attention where they’re causing economic damages to humans or declines in native species, but they’re often not investigated that much within their own native range.”

In the University’s press release, Larson said, “I think we underestimate how rich the biological world around us can be.”

A study that has been in the works for years came to fruition as the research team used genome skimming to identify these new species. 

Genome skimming and mitochondrial sequencing

Larson has been using the genome skimming method since his doctoral studies. He and his team used mitochondrial DNA to distinguish crayfish species. This helped them unravel the mystery of the two different species, marking the end of a more than decade-long research effort.

Larson originally published papers in 2012 using mitochondrial DNA to identify anomalies in the Signal Crayfish population. It provided some insights but remained inconclusive. This prompted Larson to take a new approach in 2016.

“The mitochondria is only maternally inherited, you could miss things by not working in the nuclear genome of the cell,” Larson said. “In 2016, we attempted to redo this with a nuclear marker, and it didn’t work very well. If you sequence an entire mitochondrial genome — that might be 15,000 or 16,000 base pairs — you get a little more power to tell what was in your water, soil or air.”

Even though specific methods helped them find these new species, Larson said a little accident helped them uncover these species fully.

“We were able to get these crayfish sequenced by genome skimming on this nationwide project for bio genomes in Canada,” Larson said. “But almost an accident on our side is that the genome skimming process also recovers some repetitive nuclear markers and ribosomal markers … and those were confirmatory of our past mitochondrial work.”

While the discovery of new species brings a wave of excitement, this study was accompanied by an unfortunate reality — these new crayfish species are already under threat from invasive species.

At risk

The Okanagan Crayfish, named after the Okanagan geographic region, and the Misfortunate Crayfish are both under threat from invasive species such as the Rusty Crayfish and the Virile Crayfish. These aquatic ecosystems are being damaged by such invasive species, making conservation of native species exceedingly difficult. 

“In a lot of situations, crayfish just don’t get along with other crayfish,” Larson said. “If we move a non-native crayfish to a new range, it will often spread and become invasive and displace the crayfish that’s already there.”

In fact, the name Misfortunate Crayfish comes from the animal’s situation in its native environment. 

“When I looked at that region, the crayfish occurs in this Malheur region,” Larson said. “So we used the Latin name — malherensis, and that meant misfortune.”

Human activities in these biodiverse areas over the years have triggered the increase in invasive species. Activities such as aquaculture, use of crayfish as fishing bait, aquarium dumps and classroom releases have contributed to the movement of invasive species into native habitats. 

Some of these invasions are intentional while others are accidental. These not only threaten native crayfish species but also damage human infrastructure and economic pathways.

“A small handful of those that are really successful invasives have harmed fisheries,” Larson said. “They’ve had economic damages to infrastructure when they burrow into things like earth and dams, and they can replace native crayfish by disease transmission or competitive displacement for shelter or food.”

According to Larson, it is exceedingly difficult to separate invasive species that have already invaded native habitats. The best bet is to spread awareness to prevent future mixing of species in non-native territories. 

Education and prevention

Larson and his team have begun the conservation efforts by identifying two species that are under threat. The next step is to spread awareness regarding conservation. Larson believes there’s not much that can be done for the Misfortunate Crayfish, but educational policies can protect whatever is left of them.

“What both of these species need, mostly, is to not have crayfish introduced over their populations by people,” Larson said. “And that’s largely just not releasing live fishing bait, not releasing aquarium pets. A lot of that is outreach or education from our agencies or university extension staff about not moving and releasing organisms around.”

While awareness plays a pivotal role in protecting these species, Larson thinks policymakers can make a huge difference in conservation efforts. These endeavors can vary based on the species of crayfish as both differ from each other and are found in different geographical locations. 

“Protecting the Misfortunate Crayfish is as largely about connectivity management,” Larson said. “Where barriers on the landscape exist, that keep the Rusty Crayfish from spreading to Misfortunate Crayfish populations. 
We want to maintain those barriers. If those are natural waterfalls or water diversions or dams on the landscape, we want to take care that humans don’t help the invasive move around that barrier.”

The Okanagan Crayfish is found around the Okanagan plateau and lake where conservation efforts need to be different, as it is about more than just maintaining barriers. 

“It’s often in these kinds of plateau lakes, like on the edge of the Cascade mountains,” Larson said. “Where the outlet streams of those lakes are things where we can potentially install barriers or maintain existing barriers that would keep the invasive crayfish in that region from moving up into those lakes.”

The road ahead

The discovery of two native species within an already well-studied habitat sends an important message to future research and conservation efforts. Despite researchers’ best efforts, nature still manages to surprise humans. 

Discovering hidden species like these may be the first step in protecting them. As invasive threats grow, humans need to be more aware of their activities and how it is damaging the ecosystem around them. 

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