The American lobster fishery is one of the most valuable fisheries in the United States, but stocks are increasingly affected by climate change and disease. One temperature-driven threat is epizootic shell disease (ESD), which damages the lobster's shell, potentially leading to secondary infection and death. Warmer water temperatures are associated with higher prevalence and severity of ESD. The broad geographic range of American lobsters, from North Carolina, USA to southern Labrador, Canada, raises questions about how populations vary in susceptibility to disease and whether they may respond differently to stressors associated with ESD. Understanding these population-specific responses, as well as the factors driving the incidence and severity of the disease, is critical for assessing population-level impacts and the resilience of the species under future climate conditions.
In this Editor's Choice article, Rocker and colleagues investigated by conducting a 141-day common-garden experiment using lobsters sourced from the Gulf of Maine (Casco Bay, Maine) and Southern New England waters (Niantic Bay, Connecticut and Buzzards Bay, Massachusetts). Lobsters were maintained in either cool water (13°C, associated with lower ESD prevalence) or warm water (20°C, associated with higher ESD prevalence and severity). The study also accounted for molt stage, as molting is the only known way that lobsters can shed diseased or damaged shells and the duration of intermolt influences disease progression.
Results show clear population-level differences. Lobsters from the Gulf of Maine were more susceptible to ESD than those from southern New England and had accelerated ESD progression. Warmer water temperatures increased both disease prevalence and severity across all populations but also stimulated molting, particularly in lobsters from Maine. These findings demonstrate that ESD is influenced by the interaction of water temperature, source population, and molting.
This study provides the first population-specific assessment of how molting interacts with temperature to affect ESD progression in American lobsters. By revealing how temperature, molt phenology, and source population jointly shape ESD outcomes, this work provides population-specific insights for managers to better understand ESD progression across populations subjected to warming waters.
Read the full paper, Population- and temperature-dependent variation in molt phenology and disease susceptibility shape epidemiological outcomes in American lobster (Homarus americanus), in ICES Journal of Marine Science.
