The perfect invader: a parthenogenic crayfish poses a new threat to Madagascar’s freshwater biodiversity
In 2007 an unusual crayfish found in food markets in the capital of Madagascar was preliminarily identified as Procambarus ‘Marmorkrebs’: a new world taxa and the only decapod known to reproduce by parthenogenesis. We present information on the identity, distribution and ecology of this recent invader and attempt to evaluate the threat it poses to Madagascar’s biodiversity and to livelihoods. The species appears to be currently limited to the area close to Antananarivo, but is being sold alive on major transport routes. We present molecular evidence of its taxonomic relationships and confirm that the Procambarus present in Madagascar is indeed the parthenogenic taxa. We investigate its reproductive ecology and find Procambarus ‘Marmorkrebs’ to have an extremely high fecundity; more than six times that of the native crayfish Astacoides. The limited evidence we have suggests that this species poses a serious threat to freshwater biodiversity and that it is likely to damage human livelihoods (through its impact on fishing and possibly rice agriculture). More research is urgently needed but in the meantime action is needed to reduce the rate of spread before it is too late.
KeywordsAphanomyces Astacoides Exotic Invasive species Marbled crayfish Procambarus
Thanks to K. Crandall, R. Jenkins, Aidan Keane, A. Ratsimbazafy, students in the Department of Animal Biology, University of Antananarivo, The Leverhulm Trust and Conservation International Madagascar.
- Burnham K, Anderson D (1998) Model selection and inference: a practical information theoretical approach. Springer-Verlag, New YorkGoogle Scholar
- Goodman SM, Benstead JP (2003) The natural history of Madagascar. The University of Chicago Press, Chicago, USAGoogle Scholar
- Huner JV (2002) Crayfish of commercial importance: Procambarus. In: Holdich DM (ed) Biology of freshwater Crayfish. Blackwell Science, Oxford, UK, pp 541–584Google Scholar
- R Core Development Team (2007) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org
- Rosenzweig ML (2001) The four questions: what does the introduction of exotic species do to diversity? Evol Ecol Res 3:361–367Google Scholar
- Sparks JS, Stiassny MLJ (2003) Introduction to the freshwater fishes. In: Goodman SM, Benstead JP (eds) The natural history of Madagascar. The University of Chicago, Chicago, USA, pp 849–864Google Scholar
- Zwickl DJ (2006) Genetic algorithm approaches for the phylogenetic analysis of large biological sequence datasets under the maximum likelihood criterion. Ph.D. dissertation, The University of Texas at AustinGoogle Scholar