Abstract
Monitoring of Karenia brevis blooms heavily relies on the enumeration and identification of cells for accurate and timely reports. Karenia brevis morphology however, can vary depending on life stage and environmental conditions, making accurate confirmation increasingly difficult. The documentation of spherical K. brevis cells, thought to be the result of various unfavorable conditions, has been recorded in the literature and observed by several laboratories. Conditions in which rounded cells have been observed include low salinity, low light, temperature variations, and nitrogen deficiency. Similar morphological changes have been seen in cells exposed to the amine putrescine, the algaecide curcumin, and synthetic rubbers. Although many dinoflagellate species form cysts in response to unfavorable conditions, the ability of K. brevis to form cysts has not been conclusively determined, nor has the viability and fate of these rounded cells been examined. The objective of this study was to determine the viability of these cells by evaluating brevetoxin production, cell division, and to assess whether or not these cells can morphologically recover. In addition to broadening criteria for K. brevis cell identification, results from this study can shed light on the possibility of cells recovering from natural and artificial stressors, such as those used in various mitigation strategies.
