Population ecology of an alien warm water crayfish (Procambarus clarkii) in a new cold habitat

Procambarus clarkii is one of the worst invasive and best-studied crayfish species worldwide, but its life history at higher latitudes is poorly understood. In the present study, the population ecology of P. clarkii was studied for the first time within its northeastern range limit in Europe (southern Germany) for a two-year period, and the findings are used to discuss several life-history parameters across different latitudes of its current distribution range. The reproductive cycle was tracked using the gonadosomatic index and reproductive traits in females and the reproductive form in males. Life-history parameters were estimated using Von Bertalanffy's growth function. Reproduction was univoltine and occurred from late summer to autumn. A small proportion of females carried eggs throughout the winter. This contrasts with the species' multi-voltine life cycle at lower latitudes, with year-round breeding and several reproduction peaks per year. Growth was estimated to be slower than at lower latitudes, whereas longevity, mean lifetime and size increased. These changes in life history probably reflect a general phenomenon at higher latitudes and, thus, latitudinal clines. The presented findings provide evidence that P. clarkii is able to cope well with new cold habitats by modulating its life history.