Combined effects of soil moisture and carbaryl to earthworms and plants: Simulation of flood and drought scenarios

Studying tolerance limits in organisms exposed to climatic variations is key to understanding effects on behaviour and physiology. The presence of pollutants may influence these tolerance limits, by altering the toxicity or bioavailability of the chemical. In this work, the plant species Brassica rapa and Triticum aestivum and the earthworm Eisenia andrei were exposed to different levels of soil moisture and carbaryl, as natural and chemical stressors, respectively. Both stress factors were tested individually, as well as in combination. Acute and chronic tests were performed and results were discussed in order to evaluate the responses of organisms to the combination of stressors. When possible, data was fitted to widely employed models for describing chemical mixture responses. Synergistic interactions were observed in earthworms exposed to carbaryl and drought conditions, while antagonistic interactions were more representative for plants, especially in relation to biomass loss under flood-simulation conditions.

► Climate variations may cause changes on chemicals’ toxicity or bioavailability.
► Earthworms and plants are exposed simultaneously to carbaryl and flood and drought conditions.
► The IA model and possible deviations were used to evaluate combination exposures.
► Synergism was observed for earthworms exposed to carbaryl and drought conditions.
► Antagonistic interactions were observed for plants, in flood conditions and carbaryl.