In a new study conducted by Illinois Natural History Survey, scientists discovered by chance that the virile crayfish species, faxonius virilis, are interbreeding with native crayfish in the Current River in Missouri, leading to disruptions in the ecosystem. The study, published in the Journal Aquatic Invasions, also mentioned the species are going through biological inversion that may lead to the extinction of native species.
Christopher Taylor, a curator of crustaceans at the Illinois Natural History Survey and coauthor of the study, found that the virile crayfish is one of the “widest-ranging native crayfish in North America.” Even though it is native to North America, the virile species is considered invasive in most parts of the U.S. It eventually dominates other species in every territory it is introduced.
Taylor conducted the study with other researchers including Professor Eric Larson of the Natural Resources and Environmental Sciences department at the University of Illinois.
“The Ozarks in Missouri and Arkansas are just a great place to be a crayfish,” Larson said. “The streambeds are rocky so you can hide from fish predators, the water chemistry is good, there’s lots of calcium in the stream and there are a lot of groundwater springs that feed into the main river. That’s why there are so many native crayfish there.”
The problem with crayfish interbreeding is that the hybrid species displace the native ones. This, in turn, reduces the production of native crayfish and cuts down their reproduction. Furthermore, the hybrid species consume large quantities of aquatic plants and other invertebrates. As a result, interbreeding ends up affecting the populations of other small fish and species in the ecosystem.
“The spread and impacts of an invasive species could cause substantial harm to this unique ecosystem,” Larson said.
The researchers found it was difficult to determine that the crayfish species were interbreeding since their offspring did not have unique physical appearances. It was only through mitochondrial DNA sampling that the researchers identified traces of the unique DNA within each other.
“Initially, we were finding that some of the native spot-handed crayfish, faxonius punctimanus, had mitochondrial DNA sequences that were aligning with invasive virile crayfish,” said Zachary Rozansky, a graduate student who led the research. “We did not observe any differences in colors or patterns indicating they were hybrids. They looked like one or the other.”
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