Thermal performance of juvenile American lobsters (Homarus americanus) from different Eastern Canadian locations

Using a novel laboratory system, we exposed early benthic juvenile American lobsters (Homarus americanus), raised from ovigerous females coming from three Eastern Canadian locations, to 15 temperatures (5-28°C) and followed their development for approximately four months. We calibrated thermal performance curves (TPCs) for survival and growth rate, and the relationships were well described by Weibull functions with an exponential increase from 5 to ~16 °C, a levelling-off before the thermal optimum of ~21°C and a rapid decline above the optimum; no individual survived to the end of the experiment above 26 °C. No regional thermal adaptation was detected as the TPCs were similar among locations despite their summer temperatures varying by ~10°C. Finally, molt frequency and molt carapace length increment were also well described by Weibull functions with gradual increases in rate until the optimum (22.7 and 20.7°C, respectively), followed by mild decreases beyond the optimum. These results could serve as an important component of future modeling approaches to incorporate the effect of temperature in the population dynamics of the most important commercial marine species in North America.