Laboratory experiments on nematodes from natural CO2 springs reveal species-specific tolerance to extreme CO2 concentrations

This study focuses on the CO2-tolerance of soil nematodes from natural CO2 springs (mofette fields). In laboratory experiments, we compared survival, reproduction, activity and reactivation of a CO2-sensitive species with a CO2-tolerant species. Both species survived even 100% CO2, but in an inactive state. The higher the CO2 concentration the more individuals entered inactivity. We found significant differences between the two species: more adults of the CO2-tolerant species maintained activity and reproduction at higher CO2 concentrations. Moreover, reactivation after inactivity was faster. Together with a higher juvenile mortality of the CO2-sensitive species, these interspecific differences are conclusive to explain the niche separation of the two species that was observed in the mofette field.