Effects of combined exposure to temperature, salinity, and microplastic fibres on biological endpoints in the American lobster (Homarus americanus)

To assess the effects of climate change stressors and microplastic pollution on early life stages of the American lobster (Homarus americanus), we conducted two experiments on the (1) combined effects of temperature and salinity on stage I and II larvae and (2) the combined effects of salinity and microplastic fibres on stage I larvae. To analyze their effects on H. americanus larvae in-vivo parameters including survival, heart rates, and tail flips were assessed. Results show, elevated temperature significantly (P<0.05) reduced survival and was identified as the primary stressor in this experiment and was positively correlated with heart rate. Furthermore, both stages I and II tested showed increased susceptibility to low salinity under high temperature conditions (25 PPT at 25 °C). These in-vivo effects were further validated by oxidative stress biomarkers including ROS and GST. Interestingly, there was no significant (P<0.05) differences observed in survival in response to all microplastic fibre concentrations tested (0, 0.3, 5, and 10 MPF mL⁻¹). No significant (P<0.05) differences were observed in moulting, but 10 MPF mL⁻¹ at control salinity group had the greatest number of moults compared to all other treatment groups. Microplastic fibres were observed within the carapace and the stomach of exposed larvae.