A recent NCCOS-sponsored study by the Smithsonian Institution showed that long-term exposure to daily fluctuations of hypoxia (low dissolved oxygen) increased Dermo disease (Perkinsus marinus) infection in previously uninfected eastern oysters. Surprisingly, daily-cycling pH (a measure of acidity) did not affect Dermo disease infection levels in conjunction with daily-cycling hypoxia or with continuous normal oxygen levels when compared to non-daily-cycling pH treatments. As it turns out, daily-cycling pH may actually improve the immune response of oysters. Counts of oyster immune system cells indicate that daily-cycling pH stimulates the oyster immune system. By contrast, daily-cycling hypoxia conditions suppressed immune function, supporting findings of higher disease infection under severe daily-cycling hypoxia.

These results suggest that coastal resource managers should consider daily-cycling environmental conditions in habitat restoration due to the possible population-level effects on organisms, including increasing disease. Climate change and estuarine eutrophication (nutrient loading that fuels overgrowth of algae) could potentially create such daily-cycling conditions that, if severe enough, could lead to an increased incidence of disease in estuarine organisms.

For more information, contact David.Kidwell@noaa.gov .