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.