Temperature mediates secondary dormancy in resting cysts of Pyrodinium bahamense (Dinophyceae)

Journal of Phycology
By: , and 



High‐biomass blooms of the toxic dinoflagellate Pyrodinium bahamense occur most summers in Tampa Bay, Florida, USA, posing a recurring threat to ecosystem health. Like many dinoflagellates, P. bahamense forms immobile resting cysts that can be deposited on the seafloor—creating a seed bank that can retain the organism within the ecosystem and initiate future blooms when cysts germinate. In this study, we examined changes in the dormancy status of cysts collected from Tampa Bay and applied lessons from plant ecology to explore dormancy controls. Pyrodinium bahamense cysts incubated immediately after field collection displayed a seasonal pattern in dormancy and germination that matched the pattern of cell abundance in the water column. Newly deposited (surface) cysts and older (buried) cysts exhibited similar germination patterns, suggesting that a common mechanism regulates dormancy expression in new and mature cysts. Extended cool‐ and warm‐temperature conditioning of field‐collected cysts altered the cycle of dormancy compared with that of cysts in nature, with the duration of cool temperature exposure being the best predictor of when cysts emerged from dormancy. Extended warm conditioning, on the other hand, elicited a return to dormancy, or secondary dormancy, in nondormant cysts. These results directly demonstrate environmental induction of secondary dormancy in dinoflagellates—a mechanism common and thoroughly documented in higher plants with seasonal growth cycles. Our findings support the hypothesis that a seasonal cycle in cyst germination drives P. bahamense bloom periodicity in Tampa Bay and point to environmentally induced secondary dormancy as an important regulatory factor of that cycle.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Temperature mediates secondary dormancy in resting cysts of Pyrodinium bahamense (Dinophyceae)
Series title Journal of Phycology
DOI 10.1111/jpy.12883
Volume 55
Issue 4
Year Published 2019
Language English
Publisher Wiley
Contributing office(s) Coastal and Marine Geology Program, St. Petersburg Coastal and Marine Science Center
Description 32 p.
First page 924
Last page 955
Country United States
State Florida
Other Geospatial Tampa Bay
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