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Wednesday, October 10, 2018. 1:00 PM. Webinar: American Lobster in a Pinch? Epizootic Shell Disease and the Decline of the Southern New England Stock.   Maya Groner, U. S. Geological Survey Western Fisheries Science Center. Sponsored by NOAA. More information.

Abstract: Maladaptive changes in phenology resulting from altered timing of environmental cues (phenological mismatch), is an increasing concern in many ecological systems, yet its effects on disease processes are poorly characterized. American lobster (Homarus americanus) is declining at its southern geographic limit. Rising seawater temperatures are associated with seasonal outbreaks of epizootic shell disease (ESD), which peaks in prevalence in the fall. We used a 34-year mark-recapture dataset to investigate relationships between temperature, molting phenology, and ESD in Long Island Sound. Warming spring temperatures are correlated with earlier spring molting. Lobsters lose diseased cuticle by molting, and early molting increases the intermolt period in the summer, when disease prevalence is increasing to a fall peak. In juvenile and adult male lobsters, September ESD prevalence is correlated with early molting, while October ESD prevalence is correlated with summer seawater temperature. This suggests that temperature-induced molting phenology affects the timing of the onset of ESD, but later in the summer this signal is swamped by the stronger signal of summer temperatures, which we hypothesize are associated with an increased rate of new infections. October ESD prevalence was ∼80% in years with hot summers and ∼30% in years with cooler summers. Diseased lobsters are more than twice as likely to die than healthy lobsters. Therefore, the population impacts of ESD are expected to increase with increasing seawater temperatures. These results more broadly demonstrate the powerful application of mark-recapture methodologies for inferring disease processes in fished species.

About the Speaker: Maya Groner is an ecologist, interested in how shifting relationships between hosts, pathogens and the environment alter disease processes in marine and freshwater ecosystems. Her research is highly quantitative and frequently employs field and lab studies, mathematical modeling and fisheries models. Some of the study systems she has focused on include chytridiomycosis in amphibians, seastar wasting in asteroids, eelgrass wasting disease on eelgrasses, mycobacteriosis in striped bass, epizootic shell disease in American lobster, sea louse infections of salmonids and a variety of diseases in Pacific herring. Maya Groner is a research scientist at the Prince William Sound Science Center in Cordova, AK, however she spends much of her time at the U. S. Geological Survey’s Marrowstone Marine Field Station and Western Fisheries Research Center in WA.