Tag Archives: crayfish

Charting The Spread Of Invasive Crayfish

Image Credit: Nature.Catcher, CC BY-SA 2.0, Image Cropped

Distribution and establishment of the alien Australian redclaw crayfish, Cherax quadricarinatus, in the Zambezi Basin (2021) Madzivanzira, South et al., Aquatic Conservation, https://doi.org/10.1002/aqc.3703

The Crux

While some of us may love certain seafood, and are willing to carry that seafood all over the globe, often the local species are none to happy about it. Such is the case with the Australian redclaw crayfish, a rare example of Australia finally delivering back to the world that which it has received so many of – an invasive species. The redclaw is actually one of nine crayfish that has been introduced to mainland Africa, and if their record (and the records of other crayfish species) is anything to go by, it could mean everything from the spread of parasites and complete ecosystem upheaval to severe damage to the local fishing industry.

It’s crucial to figure out exactly where invasives have spread to, and how quickly they’ve done it. It allows managers and conservation experts in other areas to prepare, and to keep an eye out. This week’s team tried to determine how quickly the crayfish are spreading from their introduction point in the Zembezi River Basin.

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Victory May Not Guarantee Survival in Species Conflicts

Spreading of the Australian yabby has led to decreases in other local species. But what happens when these species meet?
Spreading of the Australian yabby has led to decreases in other local species. But what happens when these species meet? (Image Credit: Daiju Azuma, CC BY-SA 2.5, Image Cropped)
Insight into invasion: Interactions between a critically endangered and invasive cray fish (2018) Lopez et al., Austral Ecology, doi:10.1111/aec.12654

The Crux

When we talk about invasive species, often the first thing that pops into our minds are things like feral cats, wild pigs, vicious newcomers that wipe out species or transform vast areas. But often what we focus on less are species which arrive and simply outcompete the locals.

The yabby (Cherax destructor) is one such invader. An Australian species, it has been introduced to new waterways through the country and is now threatening other species, including the Falls Spiny Crayfish (Euastacus dharawalus) in eastern New South Wales, Australia. The introduction of the yabby has resulted in a decreasing habitat range for the crayfish, but what sort of mechanisms are causing this? This experiment aimed to document interactions between the two species.

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