An oyster population model coupled with a model for Haplosporidium nelsoni, the causative agent of the oyster disease MSX, was used with salinity time-series constructed from Delaware River flow measurements to study environmentally-induced variations in the annual cycle of this disease. Simulations with this model were designed to investigate the effect of increased or decreased spring freshwater discharge, the timing of high freshwater runoff, the presence or absence of a fall or late spring phytoplankton bloom, and the occurrence of a warm winter on MSX prevalence and intensity in Delaware Bay oyster populations. Model simulations for the lower Bay site reproduced the annual cycle observed in the lower Delaware Bay. Simulations at upper Bay (low salinity) and lower Bay (high salinity) sites produced MSX prevalences and intensities that were consistent with field observations. Warm winters prevented the loss of MSX infections during the winter, causing higher MSX infection levels in the spring and almost 100% mortality by July. These simulations demonstrate the importance of salinity and temperature in altering and controlling the MSX annual cycle.
","abstract_html":"<p>An oyster population model coupled with a model for Haplosporidium nelsoni, the causative agent of the oyster disease MSX, was used with salinity time-series constructed from Delaware River flow measurements to study environmentally-induced variations in the annual cycle of this disease. Simulations with this model were designed to investigate the effect of increased or decreased spring freshwater discharge, the timing of high freshwater runoff, the presence or absence of a fall or late spring phytoplankton bloom, and the occurrence of a warm winter on MSX prevalence and intensity in Delaware Bay oyster populations. Model simulations for the lower Bay site reproduced the annual cycle observed in the lower Delaware Bay. Simulations at upper Bay (low salinity) and lower Bay (high salinity) sites produced MSX prevalences and intensities that were consistent with field observations. Warm winters prevented the loss of MSX infections during the winter, causing higher MSX infection levels in the spring and almost 100% mortality by July. These simulations demonstrate the importance of salinity and temperature in altering and controlling the MSX annual cycle.</p>","abstract_has_math":false,"creators":["Paraso, Michelle Christine"],"institution":null,"degree_name":"Master of Science (MS)","degree_level":"Thesis","degree_discipline":"Ocean & Earth Sciences","degree_department":null,"school":null,"contributors":["Eileen E. Hofmann","Larry P. Atkinson","Susan E. Ford","John M. Klinck","Eric N. Powell"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1998,"date_issued":"1998-04-01T08:00:00Z","date_published":"1998-04-01T08:00:00Z","updated_at":"2026-07-24T03:34:39Z","subjects":["Eastern oyster","Model","MSX prevalence","Aquaculture and Fisheries","Oceanography"],"languages":[],"rights":["In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
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"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["9780591815658","https://digitalcommons.odu.edu/oeas_etds/61"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["An oyster population model coupled with a model for Haplosporidium nelsoni, the causative agent of the oyster disease MSX, was used with salinity time-series constructed from Delaware River flow measurements to study environmentally-induced variations in the annual cycle of this disease. Simulations with this model were designed to investigate the effect of increased or decreased spring freshwater discharge, the timing of high freshwater runoff, the presence or absence of a fall or late spring phytoplankton bloom, and the occurrence of a warm winter on MSX prevalence and intensity in Delaware Bay oyster populations. Model simulations for the lower Bay site reproduced the annual cycle observed in the lower Delaware Bay. Simulations at upper Bay (low salinity) and lower Bay (high salinity) sites produced MSX prevalences and intensities that were consistent with field observations. Warm winters prevented the loss of MSX infections during the winter, causing higher MSX infection levels in the spring and almost 100% mortality by July. These simulations demonstrate the importance of salinity and temperature in altering and controlling the MSX annual cycle.
"]},{"key":"dc:title","label":"Title","values":["Modeling Environmental Effects on MSX Prevalence and Intensity in Eastern Oyster (Crassostrea virginica) Populations"]}]}],"canonical_facts":{"dc:contributor":["Eileen E. Hofmann","Larry P. Atkinson","Susan E. Ford","John M. Klinck","Eric N. Powell"],"dc:creator":["Paraso, Michelle Christine"],"dc:date.available":["2019-04-16T07:00:00Z"],"dc:description.abstract":["An oyster population model coupled with a model for Haplosporidium nelsoni, the causative agent of the oyster disease MSX, was used with salinity time-series constructed from Delaware River flow measurements to study environmentally-induced variations in the annual cycle of this disease. Simulations with this model were designed to investigate the effect of increased or decreased spring freshwater discharge, the timing of high freshwater runoff, the presence or absence of a fall or late spring phytoplankton bloom, and the occurrence of a warm winter on MSX prevalence and intensity in Delaware Bay oyster populations. Model simulations for the lower Bay site reproduced the annual cycle observed in the lower Delaware Bay. Simulations at upper Bay (low salinity) and lower Bay (high salinity) sites produced MSX prevalences and intensities that were consistent with field observations. Warm winters prevented the loss of MSX infections during the winter, causing higher MSX infection levels in the spring and almost 100% mortality by July. These simulations demonstrate the importance of salinity and temperature in altering and controlling the MSX annual cycle.
"],"dc:identifier":["9780591815658","https://digitalcommons.odu.edu/oeas_etds/61"],"dc:rights":["In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
"],"dc:subject":["Eastern oyster","Model","MSX prevalence","Aquaculture and Fisheries","Oceanography"],"dc:title":["Modeling Environmental Effects on MSX Prevalence and Intensity in Eastern Oyster (Crassostrea virginica) Populations"],"thesis:degree_discipline":["Ocean & Earth Sciences"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T03:34:39Z"}