This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A new study reveals narrow-clawed crayfish, an understudied invasive species in the U.K., to be as aggressive as the well-known signal crayfish. The research, published in Biological Invasions, shows that the narrow-clawed crayfish have the potential to cause ecological damage similar to that caused by signal crayfish.
Signal crayfish are known as a damaging invasive species worldwide. Not only do they harm food webs by consuming a wide variety of food sources, but they also carry the crayfish plague. Lead author James Hodson, from the University of Leeds' School of Biology, said, "Invasive species are a major driver of biodiversity loss, particularly within freshwaters.
The narrow-clawed crayfish has potentially been overlooked by ecologists despite having numerous populations across the U.K. "Our study, which is the first looking specifically at the impact of narrow-clawed crayfish in the U.K. under different temperatures, showed they are similar predators to signal crayfish under all temperature conditions." These two species of crayfish are like freshwater lobsters and usually palm- to hand-sized. They are found in still waters such as lakes, wetlands and reservoirs, on all continents apart from Africa and Antarctica.
Both narrow-clawed crayfish and signal crayfish have big appetites for aquatic plants, algae, invertebrates and even fish eggs. Crayfish have also been known to eat each other when food sources are low. Although narrow-clawed crayfish normally have smaller populations than signal crayfish and they do not carry crayfish plague, they are still large-bodied predators that have the capacity to alter ecosystems.
"This is a real concern as we'll be seeing ecological shifts if they spread into further locations and disrupt native communities," Hodson said. "The impact on prey could also be exacerbated by global warming, as higher temperatures could increase abundance and feeding rates of invasive species." The experiment was conducted by exposing the signal crayfish and narrow-clawed crayfish to four temperatures ranging from 9C to 22C (48 to 72 degrees Fahrenheit). The team then observed and compared the two species' functional responses—how much one crayfish can consume across a range of prey densities.
This approach can also address whether rare native prey species will still be eaten by the crayfish population despite low numbers. Researchers also looked at the relative impact potential, which considers how many crayfish there are at a certain temperature as well as their predatory impact. For instance, at certain temperatures the crayfish population may be bigger, which can then exacerbate a species' predatory impact.
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