Toxin Dynamics among Populations of the Bioluminescent HAB Species from the Indian River Lagoon, FL.

Dinoflagellate species that form some of the most frequent toxic blooms are also bioluminescent, yet the two traits are rarely linked when studying bloom development and persistence. is a toxic, bioluminescent dinoflagellate that previously bloomed in Florida with no known record of saxitoxin (STX) production. Over the past 20 years, STX was identified in populations. The goal of this study was to examine toxin dynamics and associated molecular mechanisms in spatially and temporally distinct populations from the Indian River Lagoon, FL. is a key gene required for toxin biosynthesis. genotype analysis was performed on individual cells from multiple sites. Cell abundance, toxin quota cell, and and RubisCo () transcript abundance were also measured. There was a significant negative correlation between cell abundance and toxin quota cell. While the genotype was dominant at all sites, its frequency varied, but it occurred at 90-100% in many samples. The underlying mechanism for toxin decrease with increased cell abundance remains unknown. However, a strong, statistically significant negative correlation was found between transcripts and the ratio, suggesting cells make fewer transcripts as a bloom progresses. However, the influence of cells must also be considered. Future plans include bioluminescence measurements, normalized to a per cell basis, at sites when toxicity is measured along with concomitant quantification of gene and transcript copy numbers as a means to elucidate whether changes in bloom toxicity are driven more at the genetic (emergence of cells) or transcriptional (repression of in cells) level. Based on the results of this study, a model is proposed that links the combined traits of toxicity and bioluminescence in bloom development.