Severe weather events, such as long‐term droughts, are challenging for many freshwater species. To survive drought, freshwater crayfish tend to inhabit shelters or burrows where they can remain in contact with water or high humidity environments. However, it is not known whether embryogenesis or post‐embryonic development can occur without free standing water.

To address this question, members of the Laboratory of Ethology of Fish and Crayfish conducted experiments using artificial burrows with high air humidity and using marbled crayfish as a model species. The ovigerous females were transferred to simulated burrows without free water, but with high air humidity. A control group of females was kept in burrows with free water. Successful hatching was achieved in both groups. In the further experiment, ovigerous females were transferred to simulated burrows with no free water but high air humidity and post‐embryonic development were observed. Following successful hatching, offspring moulted to the second developmental stage (stage 2 juveniles). Stage 2 juveniles remained viable with‐out free water for 20 days, but further development was not observed. However, when placed back into fully aquatic conditions, they moulted to independent stage 3 later on.

These results demonstrated the ability of marbled crayfish to undergo terminal phases of embryogenesis, including hatching, as well as early post‐embryonic development under high air humidity conditions only, which is not achievable in the European native crayfish. Post‐embryonic development was suspended in the absence of free water, and successfully resumed when re‐immersed. This highlights importance of drought-oriented adaptations of freshwater organisms as well as capacities of marbled crayfish as an invasive parthenogenetic species.

Detailed information can be found in the original article: 

Guo, W., Kubec, J., Veselý, L., Hossain, S.Md., Buřič, M., McClain, R., Kouba, A., 2019. High air humidity is sufficient for successful egg incubation and early post‐embryonic development in the marbled crayfish (Procambarus virginalis). Freshwater Biology 64: 1603–1612.

Kouba1 ENG Experimental design

Marbled crayfish female with eggs