The Eastern oyster (Crassostrea virginica) requires dissolved oxygen (DO) of about 4 mg/L to support proper physiological function. Hypoxia and/or microxia occur when DO decreases to ≤ 2 mg/L. Salinity and temperature changes resulting from large-scale freshwater influx have been identified as key factors influencing the oyster populations in the Mississippi Sound. It is important to investigate the impacts of DO conditions on oyster mortality, biomass, size, and condition during these freshening events. Under controlled laboratory experiments, this thesis investigated 1) the response of oysters to microxic, hypoxic, and normoxic conditions 2) the response of oysters to combined hypoxia and low salinity conditions, and 3) the response curve of oysters at various DO concentrations (0.5mg/L, 1mg/L, 2mg/L, 3mg/L, 4mg/L, and 7mg/L) under normal temperature and salinity for 28 days. This study found the highest percent mortality in microxic conditions, with total mortality by day 14. Hypoxia negatively impacts oyster tissue quality and causes a decrease in oyster biomass. There was a significant increase in the change in biomass in the hypoxia treatment while the hypoxia combined with low salinity treatment saw no statistically significant change. This study illustrates the impact of DO concentrations and the combination of hypoxia with low salinity conditions during freshening events on the biology of oysters. The oyster-specific oxygen response curve showed an increase in survival as DO concentrations increased. The oyster response curve will complement an ecosystem model to assist in predicting changes in oyster biomass and mortality during freshwater inflow events in the Mississippi Sound.
","abstract_html":"<p>The Eastern oyster <em>(Crassostrea virginica)</em> requires dissolved oxygen (DO) of about 4 mg/L to support proper physiological function. Hypoxia and/or microxia occur when DO decreases to ≤ 2 mg/L. Salinity and temperature changes resulting from large-scale freshwater influx have been identified as key factors influencing the oyster populations in the Mississippi Sound. It is important to investigate the impacts of DO conditions on oyster mortality, biomass, size, and condition during these freshening events. Under controlled laboratory experiments, this thesis investigated 1) the response of oysters to microxic, hypoxic, and normoxic conditions 2) the response of oysters to combined hypoxia and low salinity conditions, and 3) the response curve of oysters at various DO concentrations (0.5mg/L, 1mg/L, 2mg/L, 3mg/L, 4mg/L, and 7mg/L) under normal temperature and salinity for 28 days. This study found the highest percent mortality in microxic conditions, with total mortality by day 14. Hypoxia negatively impacts oyster tissue quality and causes a decrease in oyster biomass. There was a significant increase in the change in biomass in the hypoxia treatment while the hypoxia combined with low salinity treatment saw no statistically significant change. This study illustrates the impact of DO concentrations and the combination of hypoxia with low salinity conditions during freshening events on the biology of oysters. The oyster-specific oxygen response curve showed an increase in survival as DO concentrations increased. The oyster response curve will complement an ecosystem model to assist in predicting changes in oyster biomass and mortality during freshwater inflow events in the Mississippi Sound.</p>","abstract_has_math":false,"creators":["Obafemi, Abiola"],"institution":null,"degree_name":"Master of Science (MS)","degree_level":"Masters Thesis","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Dr. Kim de Mutsert","Dr. Chet Rakocinski","Dr. Reginald Blaylock"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-08-01T07:00:00Z","date_published":"2024-08-01T07:00:00Z","updated_at":"2026-07-24T05:45:40Z","subjects":["Eastern oyster","Dissolved oxygen","Hypoxia","Microxia","Freshwater infliux","Climate change","Water quality","Life Sciences"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://aquila.usm.edu/masters_theses/1059","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. Kim de Mutsert","Dr. Chet Rakocinski","Dr. Reginald Blaylock"]},{"key":"dc:creator","label":"Author","values":["Obafemi, Abiola"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2024-06-19T07:00:00Z"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Masters Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Eastern oyster","Dissolved oxygen","Hypoxia","Microxia","Freshwater infliux","Climate change","Water quality","Life Sciences"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://aquila.usm.edu/masters_theses/1059"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The Eastern oyster (Crassostrea virginica) requires dissolved oxygen (DO) of about 4 mg/L to support proper physiological function. Hypoxia and/or microxia occur when DO decreases to ≤ 2 mg/L. Salinity and temperature changes resulting from large-scale freshwater influx have been identified as key factors influencing the oyster populations in the Mississippi Sound. It is important to investigate the impacts of DO conditions on oyster mortality, biomass, size, and condition during these freshening events. Under controlled laboratory experiments, this thesis investigated 1) the response of oysters to microxic, hypoxic, and normoxic conditions 2) the response of oysters to combined hypoxia and low salinity conditions, and 3) the response curve of oysters at various DO concentrations (0.5mg/L, 1mg/L, 2mg/L, 3mg/L, 4mg/L, and 7mg/L) under normal temperature and salinity for 28 days. This study found the highest percent mortality in microxic conditions, with total mortality by day 14. Hypoxia negatively impacts oyster tissue quality and causes a decrease in oyster biomass. There was a significant increase in the change in biomass in the hypoxia treatment while the hypoxia combined with low salinity treatment saw no statistically significant change. This study illustrates the impact of DO concentrations and the combination of hypoxia with low salinity conditions during freshening events on the biology of oysters. The oyster-specific oxygen response curve showed an increase in survival as DO concentrations increased. The oyster response curve will complement an ecosystem model to assist in predicting changes in oyster biomass and mortality during freshwater inflow events in the Mississippi Sound.
"]},{"key":"dc:title","label":"Title","values":["Investigating the Response of the Eastern Oyster (Crassostrea virginica) to Low Dissolved Oxygen Conditions"]}]}],"canonical_facts":{"dc:contributor":["Dr. Kim de Mutsert","Dr. Chet Rakocinski","Dr. Reginald Blaylock"],"dc:creator":["Obafemi, Abiola"],"dc:date.available":["2024-06-19T07:00:00Z"],"dc:description.abstract":["The Eastern oyster (Crassostrea virginica) requires dissolved oxygen (DO) of about 4 mg/L to support proper physiological function. Hypoxia and/or microxia occur when DO decreases to ≤ 2 mg/L. Salinity and temperature changes resulting from large-scale freshwater influx have been identified as key factors influencing the oyster populations in the Mississippi Sound. It is important to investigate the impacts of DO conditions on oyster mortality, biomass, size, and condition during these freshening events. Under controlled laboratory experiments, this thesis investigated 1) the response of oysters to microxic, hypoxic, and normoxic conditions 2) the response of oysters to combined hypoxia and low salinity conditions, and 3) the response curve of oysters at various DO concentrations (0.5mg/L, 1mg/L, 2mg/L, 3mg/L, 4mg/L, and 7mg/L) under normal temperature and salinity for 28 days. This study found the highest percent mortality in microxic conditions, with total mortality by day 14. Hypoxia negatively impacts oyster tissue quality and causes a decrease in oyster biomass. There was a significant increase in the change in biomass in the hypoxia treatment while the hypoxia combined with low salinity treatment saw no statistically significant change. This study illustrates the impact of DO concentrations and the combination of hypoxia with low salinity conditions during freshening events on the biology of oysters. The oyster-specific oxygen response curve showed an increase in survival as DO concentrations increased. The oyster response curve will complement an ecosystem model to assist in predicting changes in oyster biomass and mortality during freshwater inflow events in the Mississippi Sound.
"],"dc:identifier":["https://aquila.usm.edu/masters_theses/1059"],"dc:subject":["Eastern oyster","Dissolved oxygen","Hypoxia","Microxia","Freshwater infliux","Climate change","Water quality","Life Sciences"],"dc:title":["Investigating the Response of the Eastern Oyster (Crassostrea virginica) to Low Dissolved Oxygen Conditions"],"thesis:degree_level":["Masters Thesis"],"thesis:degree_name":["Master of Science (MS)"]},"updated_at":"2026-07-24T05:45:40Z"}