Preservation of Dinoflagellate Cysts in Different Oxygen Regimes: Differences in Cyst Survival between Oxic and Anoxic Natural Environments

This quantitative dinoflagellate cyst study reveals an enormous difference in survival rates oxygenated versus anoxic sediments. Replicate samples of concentrated natural cysts with the same initial species composition (1.4 × 104 resting cysts·cm−3 sediment, 61% filled live-appearing contents) were placed bags 20 µm plankton screen. containing 10.0 cm−3 on seafloor different environments Long Island Sound, USA (anoxic and oxygenated), as well refrigerated test tubes laboratory. Three sets 15 each environment. Once every year for four consecutive years, three recovered from set, contents analyzed by counting germination experiments. An preservation potential between was revealed. The number decreased abruptly within first oxygen-rich environment; living became very rare (only 5% remained) also empty walls disappeared (20% total remained). In sediment samples, significantly time, but less quickly. After 1 year, 35% environment 70% remained intact. 4 21% remained, 31% tubes. intact a longer time under conditions, especially known to fossilize well. Germination experiments showed that likely alive, because identifiable identified vegetative cells corresponding slurry cultures. assemblage dominated Protoperidinaceae, Dipolopsalidaceae, Gonyaulacaceae. Of special interest is ichthyotoxic Margalefodinium polykrikoides, bloom-forming Peridinium quinquecorne, which has undescribed cyst, previously Krypoperidinium species. results show greater “dead-zone sea bottoms” may provide answer question absence beds area despite observed sedimentation dense blooms.