Abstract:

Capitella teleta are annelid polychaete worms that live in the sediment of marine estuarian environments. They represent excellent organisms for testing behavioural changes in response to chemical exposures that are common in coastal waters. Serotonin, dopamine, and acetylcholine pathways play important roles in cognitive and behavioural functions, such as locomotion. Exposure to chemical toxicants found environmentally can impact these pathways, potentially altering behavioural responses of Capitella. Our previous work identified conserved locomotory responses of adult Capitella, developing an assay to screen in exogenous chemicals, such as nicotine and estradiol. However, as early-life stages are typically more sensitive in animals, the objective of this study was to modify this assay for juvenile stages, to test the responses of this animal to neurochemicals. As we previously measured behavioural responses using petri dishes, to increase throughput, we characterized the distance moved (mm), velocity (mm/s), and time spent at the edge (s) using 6-well plates to increase throughput. Juvenile Capitella exhibit similar behavioural responses to adults, beginning the onset of movement after 1 h of being in the 6-well arena. In adults, there was a decrease in the distance moved, time at the edge, and maximum velocity when exposed to 20 µM of nicotine. In juveniles, 2 µM of nicotine increased the distance moved and maximum velocity, but decreased distance moved at 20 µM. Fluoxetine increased the time at the edge at 1 µM, and apomorphine increased the distance moved at 1 µM. Together, these results suggest that a range of neuronal targeting chemicals may influence locomotion. This assay may be useful in environmental toxicology testing by creating a higher throughput assay to screen the impact of chemical contaminants on invertebrates, particularly as this organism represents marine environments, which is essential for understanding ecological risks of human activities.