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Can an alien invasion doom our inland fisheries?

Alien crayfish pose a real threat not only to local species but also to the livelihoods of rural people.

By: Professor Olaf Weyl* and Dr Josie South, NRF-SAIAB

A team of researchers from the South African Institute of Aquatic Biodiversity (NRF-SAIAB), recently studied how invasive freshwater crayfish can affect the inland fisheries and native species.

Southern Africa has been invaded by two crayfish species - the red swamp crayfish, which is native to the southern states of the USA and Mexico, and the red-clawed crayfish, which is native to Australia. Once crayfish are introduced to a water body, they are practically impossible to remove. The team assessed what the alien species were doing to the ecosystem and how the native species responded to them. The feeding rates of the two invaders were compared to a native freshwater crab and it was found that the crab species has a higher predation rate, but when temperatures increase, the crayfish have an advantage. 

Read the full article in the NRF Science Matters magazine Vol: 4 | Issue: 3 (pages 20-21)

*  In Memoriam of Prof Olaf Weyl, who, passed away in November 2020.

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