Alteration of pH within the world’s ocean, or ocean acidification (OA), results from increased absorption of CO2 into global waters. Acidification can positively or negatively affect physiology and behavior of marine taxa, though the effects vary greatly based on species and life stage. Crustaceans are often noted as being resilient to acidification, though negative physiological and behavioral impacts have been shown. Studies on the impacts of OA on the American lobster (Homarus americanus) have primarily focused on its physiology. This thesis aims to observe the potential effects of acidification on the foraging behavior and hemolymph chemistry of juvenile American lobsters. We exposed 28 juvenile lobsters (carapace length, CL, 29mm – 52mm, average 42 +/- 1.3mm) to randomly assigned, individual pH values between 7.3 and 7.8 for 12 days to observe potential impacts of acidification. The time taken to locate blue mussels, the number of foraging trips taken, the time taken to successfully feed, and hemolymph L-lactate concentration (stress indicator) were assessed after the exposure period. Counter to our predictions, as pH decreased, lobsters successfully fed two-times quicker, maintained normal locate times of prey, and took fewer foraging trips. We found that lobsters responsed to prey cues similarly across the pH range, indicating that olfaction was likely not impaired. These results suggest that juvenile American lobsters may increase foraging activity in response to acidified conditions.
Stelling T., 2024. Behavioral and physiological effects of ocean acidification on juvenile American lobsters (Homarus americanus). MSc thesis, University of New Hampshire. Thesis (restricted access).
