Assessment of Dermo Perkinsus marinus in the “Southern Oyster” from a High‐Salinity Environment

Abstract

The prevalence and intensity of dermo Perkinsus marinus were examined in the eastern oyster Crassostrea virginica “southern oyster” population within the high salinity (35‰ or greater) waters of South Texas' lower Laguna Madre (LLM). During 2017, 192 oysters from four collection sites (approximately 111 km2 study area) were examined via culture for the presence of Perkinsus hypnospores. Additionally, dermo DNA was detected in oysters by PCR. The number of oysters infected (prevalence = 0.36), as well as the intensity of infection, were consistent within three of the four collection sites but varied between sites, suggesting that environmental differences influence P. marinus infection in the LLM. All sites showed an upward trend in the number of oysters infected as oyster size increased, yet the highest infection intensities were not found predominately in the larger oysters. Although the warm, high‐salinity waters might be expected to be ideal for dermo infection, the relative number and intensity of infections were low for most sites, suggesting that dermo in the LLM may not pose a significant threat to commercial oyster culture and that the southern oyster may be uniquely suited for developing a strain of oysters suitable for offshore culture in the Gulf of Mexico.