Critical crustaceans!

The results of a global assessment, led by scientists from the Zoological Society of London and University College London, have revealed that almost a third of the world’s species of crayfish are threatened with extinction. 

It follows a project, which took place in 2010 in collaboration with 76 experts from the IUCN Species Survival Commission (SSC), to review the conservation status of the world’s 590 species of freshwater crayfish.

The results, published today in the Philosophical Transactions of the Royal Society B, also revealed that a further four species were assessed as Extinct. The current rate of extinction seen in crayfish exceeds that of most land and marine species highlighting the imperilled status of freshwater species. 

Euastacus bindal. A very threatened species of crayfish. Photo: Diana-Angelique Virkki
Euastacus bindal. Photo: Diana-Angelique Virkki
Vulnerability to extinction varies considerably throughout this diverse group: 47% of all Australasian species were found to be threatened with extinction, with the majority of species at risk from climate change impacts (e.g. wild fires, drought), agriculture and invasive species. While overall extinction rates are lower for North American species, the southeast USA is a major threat hotspot. In contrast to Australasian species, North American species face a much greater threat from pollution, damming and urban development.  

Nadia Richman, lead author of the paper: “Crayfish vulnerability to extinction is exacerbated by their small range size with 98% of species being known from only a single country and some species known from only a single pond! One of the greatest challenges we face with conserving crayfish is the effective design of protected areas and mobilising funds for the conservation of a species that is sadly not considered charismatic.”

Orconectes australis (Southern Cave Crayfish). Photo: Guenter Schuster
Orconectes australis (Southern Cave Crayfish). Photo: Guenter Schuster

She adds: “Given the often significant biomass of crayfish in many freshwater environments, they play a critical role as ecosystem engineers and as an important food source to humans and other species”.

At present only 2% of US species and 6.6% of Australian species occur in protected areas highlighting the significant shortfall in conservation efforts for crayfish. The threat from invasive crayfish species and disease is expanding rapidly each year which if left unchecked could significantly increase the number of threatened species.

The results of this study have been published today (5 January) in the Philosophical Transactions of the Royal Society B. You can view the paper here.


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