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Don't forget to register for the first webinar in this series on
Tuesday, November 10, 2020 at 1:00 PM ET.
"Ocean Acidification and Warming Act Synergistically to Reduce Cardiac Performance and Increase Susceptibility in Juvenile American Lobster"
Presented by:
Amalia Harrington, Maine Sea Grant, University of Maine
Increased greenhouse gas emissions have caused rapid ocean warming (OW) and reduced ocean pH via acidification (OA). Both stressors will likely impact marine crustaceans, but they are often examined in isolation. We conducted an environmental stressor experiment to understand how exposure to current summer conditions, OW only, OA only, or both acidification and warming (OAW) differentially influence the thermal physiology and immune response of juvenile American lobster, Homarus americanus. Following a 42-d exposure to these stressor treatments, cardiac performance was assessed during an acute thermal stress, and lobsters were subjected to a subsequent 21-d pathogen challenge with Aerococcus viridans var. homari, the causative agent of gaffkemia. Lobsters exposed to OAW had significantly lower Arrhenius Break Temperatures (ABT; indicator of thermal limits of capacity) when compared to lobsters from all other treatments, suggesting these stressors act synergistically to reduce physiological performance. Individuals from the OW only and OAW treatments also had significantly lower total hemocyte counts (THCs; indicator of immune response) and showed a reduced median time to death (by up to 5 d sooner) post A. viridans injection compared to lobsters exposed to current summer conditions. Moreover, nearly twice as many lobsters exposed to OAW lost at least one claw during the pathogen challenge compared to all other treatment groups, potentially increasing the risk of mortality due to secondary infection. Together, these results suggest that predicted end-century OAW will impact the physiology and immune response of juvenile H. americanus, potentially influencing successful recruitment to the fishery.
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