Effects of short-term novel bait consumption on the physiology and thermal tolerance of the American lobster (Homarus americanus)

Diet is known to modulate ectotherm thermal performance, making its impacts crucial to consider in the face of climate change. Recent shifts in bait usage in the Maine lobster fishery have exposed lobsters in the Gulf of Maine to new food sources, including terrestrial–based foods, the physiological impacts of which are largely unknown. Here, we acclimated juvenile female Homarus americanus to three diets: frozen menhaden (Brevoortia tyrannus), fresh mussel (Mytilus edulis), or salted pig hide (Sus domestic). After three weeks we measured their aerobic scope, acute cardiac thermal tolerance, and pre– and post–trial hemolymph protein concentration. Results suggest lobster metabolism and acute cardiac thermal tolerance are robust to short–term nutritional variation, including starvation–like conditions. We found differences in hemolymph protein, however, indicating impacts of diet on physiological condition even if organ or animal–level performance remains unchanged. This study highlights the need for a more detailed understanding of bait usage and consumption in the Maine lobster fishery to elucidate potential impacts of fisheries management on lobsters coping with climate change.