Center for Coastal Physical Oceanography & ODU Resilience Collaborative

Fall 2019 Seminar Series


Eileen Hofmann

Monday, September 30, 2019
3:30 PM
Conference Center, Innovation Research Building II
4211 Monarch Way, Norfolk, VA 23508


Abalone populations along the California coast have been severely impacted by the marine disease, Withering Syndrome, which is caused by a rickettsia-like organism (RLO), Candidatus Xenohaliotis californiensis. A model that includes abalone growth, host susceptibility to RLO, RLO body burden, and the influence of temperature and food availability has been developed to assess biological and environmental controls on Withering Syndrome in abalone populations. The model implementation is based on experimental and field observations made for red abalone (Haliotis rufescens). Initial simulations reproduced the disease progression observed in red abalone that were held in laboratory tanks at constant temperature for more than one year. These simulations showed that after the initial infection, disease progression is determined by RLO growth in the host and that continued RLO exposure has little effect on the disease intensity. The model was then used to simulate RLO disease progression for red abalone exposed to fluctuating seawater temperature, which included warm events that persisted for days to weeks and events that persisted for months. These simluations showed that long-term sustained warm water temperatures, as occurs during El Niño conditions, encourage RLO proliferation in the host and enhanced disease progression. Shorter term warm events have little effect on RLO and disease progression. The model was also parameterized for black abalone (Haliotis cracherodii) that are infected by RLO and by RLO with a phage (hyperparasite) that reduces the growth of the pathogen. These simulations show that the occurrence of the phage significantly reduces RLO body burden and infection intensity. This abalone model provides a tool to forecast population response to environmental variations, to guide plans for conservation and restoration of wild populations, and to inform best management practices for abalone aquaculture.


Eileen Hofmann's research interests are in the areas of physical-biological interactions in marine ecosystems, environmental control and transmission of marine diseases, descriptive physical oceanography, and mathematical modeling of marine ecosystems. She has worked in a variety of marine environments, most recently the continental shelf of the Ross Sea, Chesapeake Bay, and the Middle Atlantic Bight off the east coast of the United States. She has published extensively in marine ecosystem modeling and other areas of marine research. Her contributions to modeling physical-biological interactions in marine systems were recognized by her election as Fellow of the American Geophysical Union.

Reception before seminar at 3:00 PM

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