Investigating the Sublethal Effects of Cannabis sativa on Earthworms and Trematode Cercariae

Rising demand for Cannabis sativa production and use has resulted in recent rapid widespread legalization and large-scale production. Due to its abundance and variety of unique secondary metabolites, C. sativa cultivation could pose a risk to natural terrestrial and aquatic environments. Currently, its general effects on invertebrate animals are not well studied beyond lethality. Here, I investigated how ingestion of C. sativa plant material affected the growth, mortality, and behaviour of an earthworm species. Earthworms that fed on C. sativa gained less weight and took longer to escape from an external heat stimulus. However, mortality and escape behaviour from an external light stimulus were not affected. I also investigated if exposure to aqueous cannabinoids affected the activity and longevity of free-swimming infectious cercariae of trematode (flatworm) parasites. Neither high nor low concentrations of cannabinoid solutions had any effects. Exposure to C. sativa could thus have some effects on non-target organisms.